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NTCBCIV 350 Power Issues
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By farmersamm - Wednesday, January 02, 2013 8:12 AM
Well, I blew up the hood and fender on the LN9000.

Little note to those DOT numbers on your tires. DON'T RUN TIRES THAT GOT 13 SEASONS ON THEM!! Tire had around 12/32 tread and looked good.....

Anyhow I was using the little truck to pull hay in from Texas while I tried to figure out the low power issues with the cabover. Last trip down with it was a real disaster. Returned 300 miles at the stately speed of 30mph. Geesh. So, as you can tell:D the little truck is down for a while. I need to get the big truck going. Had to make an emergency run with the 1 ton and a hay trailer. 600 miles round trip for NINE BALES OF HAY:(

The Cummins is putting out no power to speak of.

Checked fuel pressure......120psi max at governed speed with regulated shop air applied to the AFC piston. Thought it was the pump, replaced it with improvement. The max pressure will not hold for more than a second, even slightly below governed speed(this would rule out governor break I think). This seems to tell me that there's nothing holding it on the other end (injectors)

Checked for fuel line leaks and restrictions on the suction side (before I replaced the pump).........4in vac with new fuel filter. Also constructed a sight glass to check for air bubbles..none. Bypassed intake lines, and ran direct line to improvement. So the intake side is ok.

Checked boost....NONE. Even with the AFC fooled with shop air, no boost. Road boost. Pulled the turbo, and had it looked at. It was given a clean bill of health by two reputable shops. No leaks in the pressure side of the duct work, and no leaks in the aftercooler or manifold gaskets. The exhaust is apparently free of restrictions as it runs the same with exhaust unhooked.

An old timer at one of the turbo shops said "puts out enough fuel pressure to make black smoke, but not enough to make boost". I gotta agree I guess.

My only recourse is to look into the injectors. I'm thinking a bad O-ring is allowing fuel to get to the return line. Or fuel is bypassing due to faulty internals on the injectors or one of them. Big Sigh

I DESPERATELY NEED THE TIMING SPECS FOR THIS ENGINE. Cummins doesn't want to give them out, like it was some sort of Nuclear Secret or something.

The CPL is 840

The serial number is 11448726

I was able to score a gauge set for setting timing on the NT engines offa Ebay, and I've scrounged up a nice puller, and have a 6in pound torque wrench on the way (the nice t handle type). I figure I'll have to reset timing if I disturb the injectors.

I'm at the end of my rope. The only place pressure could be dropping has to be up in the head. I think I've approached the problem in a rational way, and I don't see any other alternatives. I can only think there's a hole in the end of the straw.

By Geoff Weeks - Wednesday, January 02, 2013 9:15 AM
I have one of those, and it will run with a 400 if you put enough fuel to it with the stock injectors. SO injectors aren't the problem. It is an odd ball engine in a way. Stock C/R is 17:1 and the timeing and cam are unique to that famliy (CPL 838-840). I am away from my CPL book so can't give you the timeing code right now. The stock pump runs a #27-#30 "button" in the pump (iirc), but put a #17 and it will wake up, just watch your pryro if you run any elevation it gets hot quick.

You know about the screw inside the thottle shaft right? also the no air setting on the AFC. Sounds like the AFC is messed up but you said a pump place tested it.

I don't have the fuel settings for that engine so don't know what pressure it is set to run stock.

You can't mix parts into that engine from other BIG Cam's, it will run like dog crap. It uses a special cam and the NT88 rocker boxes which are different then other Big Cams. The head is different on the NT88's from the Big Cams, the valves are flush on the NT88 head and they stick out a bit on the other Big Cam IV's.
By JCHAULER - Wednesday, January 02, 2013 6:03 PM
You can sign up for Cummins Quikserve Online for free now & it will tell you everything you want to know about your engine .
By farmersamm - Thursday, January 03, 2013 2:06 AM
JCHAULER (1/3/2013)
You can sign up for Cummins Quikserve Online for free now & it will tell you everything you want to know about your engine .

Sadly, QuickServe is a real disappointment for this engine. It gives you a CPL number, replacement fuel pump number, and the plant it was built in, and some other useless info. I don't know how much info is available for other engines.

Half my data plate is missing, and I can't even determine the timing code. The timing code is useless unless you happen to have access to a CPL Manual. All in all.....I probably will go with Detroit on any future truck purchases. They have excellent customer support. I was able to call United Engine here in Oklahoma and get a full printout of all pertinent specs on my 6-71.

IMHO Cummins has lousy customer service, at least locally. I get full support on all my ag engines with a phone call, not with Cummins.
By farmersamm - Thursday, January 03, 2013 2:35 AM

Thanks for taking the time to look for the specs.

The new pump runs at the calibrated 162psi on the test stand, but only runs at 120 on the truck. Somwhere there's been a catastrophic failure.

The truck ran out at 70mph under load since I bought it. It's always had no power on hills, have to drop a gear on long pulls. This I could live with even though I knew the motor wasn't running right. I ran these engines for years when I was a young guy, so I know what they're capable of.

Now I've got a 30mph truck, it's not an issue of wanting more power, it's an issue of having no power.

My understanding of the PT system is as follows: The pump merely puts out a measured amt of pressure for a given circumstance (load, engine speed, and boost as a function of load). The injector recieves pressure through a metering orifice. The pump will supply higher/lower pressure to meet engine demands. At different pressures the injector will recieve enough fuel to compress to injection pressure. At all times there's a full flow to the injector except when the plunger is seated in the cup (this is when the actual atomized fuel is sprayed into the cylinder). Excess fuel is sent to the return line thru another orifice in the injector. It's simply a matter of supplying varying pressure to a given size orifice which affects "fill" rates in the injector cup.

I'm not detecting noticeable fuel in the lubricating oil, so I probably have no leaks to the head.

My concern is internal leakage in the injector if that's possible. Can the injector pass enough fuel to the return to effectively bleed off considerable amounts of available pump pressure?

The engine, after sitting for more than a day, will not start without considerable cranking. Once started it runs rough consistently at idle. The rough idle does not go away at any time, even after the fuel system has pressured up.

There's a miss at cold start, which goes away after the engine reaches operating temp (or maybe the fuel system stabilizes?).

Idle fuel pressure remains at 0 (at least not enough to register on the pressure gauge) all the time. Fast idle pressure remains at 30 all the time. Full governed speed pressure remains at 60 without "boost", and will momentarily go to 120 with "boost".

This pump should run on the engine like it runs on the test stand if 25psi air pressure is supplied to the AFC piston, and you don't push it past the mechanical governed speed where the governor kicks in and dumps the fuel back to the gear pump. At least I think this is the way it should operate.

Being a fixed timing engine, it should operate about the same under all static conditions regardless of load/boost supplied by artificial means (regulated shop air).

What's your thinking on this?

By Geoff Weeks - Thursday, January 03, 2013 12:42 PM
When I get home (tomarrow I hope) I'll look at my CPL book and give you the timeing code. I'm beginning to agree with your assesment that it is a leak off problem in one or more of the injectors and/o rings. Dead simple to pull the injectors out and look. That would be my 1st step. Timeing stays put unless someone has a follower cover off or the cam is worn.

When in a hurry, I set the injector by spinning the push rod, when zero lash you are there (or close enough). I once had an injector rocker arm crack (but I was running anything but stock fuel pressure).

The rough running/ hard starting says something is bypassing somewhere. Injector O rings are a cheap/ easy place to start.
By Geoff Weeks - Thursday, January 03, 2013 1:10 PM
Had my wife look it up.( I thought I knew it off the top of my head, and I did, but didn't trust I had it right!) GM (-.101) timeing code.
By JCHAULER - Thursday, January 03, 2013 1:55 PM
If I understand engine data plate correctly , The film card line is your static timing code , that per your data plate engine would be timing code ( F ) fast: -.058 , normal: -.061, slow : -.064 piston travel : .2032 1in key # 20079 Arrow location : front please correct me if this info is incorrect
By Geoff Weeks - Thursday, January 03, 2013 2:43 PM
I have no idea what the stuff you posted is. It has no relation to the timeing code and/or the dial indicator reading for setting the timeing on a NT engine. I posted both the code and the indicator reading for that CPL in question.
By glenn akers - Thursday, January 03, 2013 4:10 PM
When checking the fuel pressure make sure and do that with a good liquid fill gauge and do that under load at governor cut off rpm. That means when you are running down the road with guage conneced to a long hose tied to the wiper on the out side run the rpm up with load watching the pressure and as it gets to governor cut off which is were you feel it stop pulling and may be around 2100 rpm then the pressure reading will start to go down. The highess reading is your rail pressure or 162 psi. With a proper snap reading gauge you can do this with the truck setting still but is better to do under load. If you do this you may find its got the proper pressure. Make sure your throdle is opening the fuel pump lever up all the way. Do this by holding down the gas pedal down and then make sure the lever has some break over.Cause it will run 2100 rpm dont mean it got full throdle.Dont wast your time checking the timing unless you have seen some one playing with it cause it dont change with wear. For as the bleeding back of the fuel, check the check valve elbo on top of the gear pump. Do it any way you want but i always pull it out and wrap my lips around it and see if i can blow thru it either way. If so go to cummins and get one. Its not just a #4 elbo.Injector o/rings do get hard and by/pas from bottom to top but is not a ever day thing.But dont start replacing the button trying to raise the fuel untill you pull a injector and check the o/rings.If you reset the rail pressure end up with about 15 to 20 psi more than specs and it will pull better.Also there is a steel ball pressed in the end of the throdle shaft that you can drill out and then if you didnt get into it with the drilling then back the screw inthere out about two turns.This will give you maybe 10 psi more fuel pressure.Like geoff stated the timing is .101
By farmersamm - Friday, January 04, 2013 4:30 AM
Thanks! This is a wealth of information, and I'm not just blowing smoke, I really appreciate it.

I'll recheck the breakover on the throttle to make sure it's right. The static tests were with my hand on the throttle lever on the pump, so low pressure readings were obtained without linkage (ie. breakover). When the cab is raised the linkage "slips" and doesn't affect the actual pump lever anymore at that point.

I never checked the elbow on the cooling line on top of the gear pump. I'll do that today. The original elbow was reinstalled on the reman pump.

I ordered some rebuilt injectors ($79 a pop), and they ought to be in today. Have to go to Tulsa to pick them up. My thinking is.....long as I have to pull everything down, I might as well replace them. I worry about spray patterns etc. on the old ones. New ones from Fleet Pride are actually cheaper, but I really don't trust a lot of their stuff. Might change my mind on replacement though, have to see I guess. Least I'll have them here if needed. I hate to just throw money at this thing, but bad injectors can do some nasty things :)

Need to call Cummins on the valve cover gaskets. This particular engine has different style covers I believe, they don't interchange with other NT's I think. I usually stick to OEM gaskets, and critical parts, for all my engines...they just work better.

This whole thing has been pretty depressing, but I feel the end is in sight now. At least I've got some good info to work with.

Looks like Henry gets a trip to the Big Town today
By Geoff Weeks - Friday, January 04, 2013 9:31 AM
Check your e-mail about a set of valve cover gaskets.
By glenn akers - Sunday, January 06, 2013 3:04 AM
Samm did you find the problem if not PM me.
By BLKHEART - Tuesday, January 08, 2013 2:46 AM
Just thought I'd throw out a simple fix. I had the same problem on my 78 KW and turned out to be fuel suction line from tank to pt fuel pump. Old line was collapsing internally upon fuel demand and could only muster 45MPH out of it. Replaced with new line and presto, 85MPH.Just a thought and much cheaper than new injectors. Good luck!
By farmersamm - Wednesday, January 09, 2013 5:13 AM
Been a bit of a holdup in the work around here. First day out of bed since Sunday morning. Flu

Geoff..I never got the Email for some reason. I checked all incoming messages including the quarantined messages. I did come up with the correct gaskets AFTER THE CUMMINS PARTS DOOOOD INFORMED ME I PROBABLY HAD THE WRONG ENGINE IN THE TRUCK.

I ask for the gasket by CPL number. He says a serial number would be better.....ok

I get the serial out of the pickup, and bring it in. I also needed some injector o-rings, and he shows me a pic of STC injectors. Not my injectors says me. This is where it got touchy. ROFL

Anyhow he finally was convinced that the numbers were right when I told the dood that QSOnline verified matching VIN# and serial# for the application. I believe the problem was he actually had to look up the parts in a BOOK (dear me).

I suppose I'll be remembered at the Cummins place. I launched into the usual tirade about the unavailability of specifications necessary to work on these things. Usual's for insurance purposes. My answer.......You can lie to the idiots, but don't lie to me. He didn't seem too sincere when he wished me a good day on my way out.

Weather permitting, I suppose the injectors go in either today or tomorrow. I'd be a lot happier if I had a spec for return flow rate to actually check if the stupid things were leaking to the return line.

My dear sweet lady has informed me that I'd be better off replacing everything on the upper end of the engine.....turbo, injectors.,...instead of messing around and either running out of hay, or having to make more trips with the 1 ton. I tend to just about always agree with her, after a lot of kicking and screaming. Hay is running 75-100 bucks a bale around here now, and every trip with the 1 ton costs as much as the semi, but only results in bringing back 9 bales instead of 22.

I hate to become one of those dreaded "parts replacers" but it's up against the wall time. She also "suggests" that even with the cost of the parts it would be less than taking the stupid thing in and letting a shop mess it up AND PAYING FOR THE SAME PARTS WHEN THEY REPLACE THE IDENTICAL PARTS BECAUSE THEY'RE NOT SURE EITHER. She is funny sometimes. Her take on the whole thing "JUST GET THE STUPID THING ON THE ROAD!!!!!!!!!!"

"yes dear"
By farmersamm - Wednesday, January 09, 2013 5:20 AM
BTW, here's some good stuff I came across that might be of interest to some of you all. The link is to one page, there's good stuff in front of, and next to this page....just check it out.

Occasionally the secrets get out. LOL

Notice the no air snap values, and the service idle pressure. I get close to the snap values, but nowhere near the idle pressure. All calibration pressures are set with a given flow rate which I assume mimicks the actual rail pressure/flow on the engine. So I still feel that I'm leaking to the return.

Not the same engine as mine, but a general starting point for analysis.
By glenn akers - Wednesday, January 09, 2013 9:58 AM
Samm your looking at apples and oranges cause that is only acheived by putting it on the test bench. As for as the rail pressure its checked by being under a load or with a snap gauge and even that is not a go way to test it. And idle pressure dont mean nothen to you if its idling right. As for a a return rat that is impossable to check cause its variable.As for a check for a restrition on the supply line do hat i have said put you a gauge in the w.s and go for a drive with a load. Or load it with the brakes and when you get full rpm no load then start to load it watching the rail pressure or fuel pressure and the hightest you get before it starts to go down is the rail pressure. it should be as you stated 162. Now with the pressure at 162 ir close remenvber your foot controls tha pressure also with the governor to hold the rpm. If the rpm drops so will your pressure.But say it hold 160 psi when you first load it keep same load on it for maybe half mile and same rpm and this pressure should not start to drop much. If you keep your foot down and rpm same and same load applyed the the pressure does start down then you fuel supply is restricked duel to stopped up filter or a pinched lie or line collaped inside. Air will also affect the rail pressure.I have also seen the steel line that goes from pump to head made from staifex hose which is a bad thing. It will collaps inside.
By glenn akers - Wednesday, January 09, 2013 10:06 AM
Samm what should the rail pressure be on your truck. The one your looking at that you said is not your engine says 162 but its different on different fuel codes.155 psi at one time is what i remenber for a 350.
By wayne graham - Wednesday, January 09, 2013 12:19 PM
Samm, Glenn has forgot more than I will ever know about this but any time I replace a pt pump it gets injectors too. The fuel line we are getting now along with this fuel dictates running new lines a lot more often than we used too. With bio diesel I am changing lines every 3 to 4 yrs. Weatherhead is what the dealers have now and the quality is poor . just my thoughts. Wayne
By glenn akers - Wednesday, January 09, 2013 12:52 PM
wayne i have some weatherhead fittings and hose on my mack fuel sysrem that is #8 in size and dont have the size of # 6 on the inside of the swivels. If it was a cat or big cummins it wouldnt even stay warm with that flow but these macks done need much flow.
By farmersamm - Tuesday, January 15, 2013 9:52 AM
Been down with the flu. Wouldn't wish this stuff on my worst enemy.

Was able to replace 3 of the injectors before I got bed bound. They seem ok, but who knows, you can't see inside the things. Tips have a little carbon about all.

Inlet screens on the new injectors are quite a bit larger than the old ones.

The last one I fooled with before taking sick was a real mess. The adjusting screw on the rocker arm is mangled (slot ruined), and the screw won't turn. Somebody got lazy, just plain dumb, or a combination of both. If I can get it out I'll probably try a thread chaser and a new screw, if not....guess it's a new rocker arm. Gotta wonder if it ever was adjusted properly considering the screw is probably cross threaded. Dunno how someone could put the rocker cover back on knowing that this had happened.
By wayne graham - Tuesday, January 15, 2013 1:12 PM
Samm, It is like the comedian Ron White says"you can't fix stupid" Wayne
By farmersamm - Wednesday, January 16, 2013 9:51 AM
About done installing the new injectors, thought I'd put up a few pics of the "typical" injector removed from the motor. Not sure if these are normal deposits, but they're a sight more than I've ever seen on the injectors from my Perkins engines
By dashby - Wednesday, January 16, 2013 3:01 PM
Injector from my 350 SC.

By glenn akers - Wednesday, January 16, 2013 3:25 PM
farmersamm (1/16/2013)
About done installing the new injectors, thought I'd put up a few pics of the "typical" injector removed from the motor. Not sure if these are normal deposits, but they're a sight more than I've ever seen on the injectors from my Perkins engines
This injector has been run many miles needing the over head run. And its not running hot enough due to cold coolant or no load. It should have been smoking.
By glenn akers - Wednesday, January 16, 2013 3:27 PM
dashby (1/16/2013)
Injector from my 350 SC.

This is a normal looking injector.
By farmersamm - Thursday, January 17, 2013 2:44 AM
The water temp runs between 170-180 according to the gauge. Slight rise when the ambient air temp is higher, but this truck is never run when the air temps are over 80 degrees. I do all my hauling in the Fall, and Winter, mostly to save tires and reduce stress on an old engine, and drivetrain. Least that's always been my plan. Even with the low flow system it never gets hot.

The last injector pulled/replaced was the #1 cylinder. I wiped it off before taking a pic The high pressure cavity was full of crud, with the screen almost 50% plugged with goop. I dunno if this was crud from the combustion chamber leaking into the cavity thru the O-ring, or whether it was stuff that wasn't cleaned out of the reman head galleries. The #1 cylinder is at the end of the line on the fuel rail, farthest from the pump, dunno if this is significant. If underfueling issues continue I suppose this cylinder is the one to look at. I'm hoping the copper sleeve isn't distorted and allowing crud into the rail. All of the crud was in the high pressure cavity, and some below the cavity on the tip side of the injector.

As far as smoke goes..............Not sure how much smoke it has been puting out. Kelly says it smoked quite a bit when I moved the truck to keep it from burning up in the wildfire that came thru here last Summer. I can't see the stack when driving due to the tiny window behind the seat so her observations are all I have to go by. The turbo is positively coated with soot on the turbine side though.

Speaking of fires. Twas quite a fire :)

The tanker going by on the highway was one of quite a few being used to haul water in for the brush pumpers. This is oil country around here, and local companies volunteer their equipment in times of fire.

We thought the fire had bypassed us on the other side of the highway, but after nightfall the wind changed and brought the fire back from the North, and blew it East right onto us. We had to literally fly up to the other end of the section while it burned thru the place. How the house was spared I'll never know. The two of us spent the next 24hrs fighting hot spots to keep it from reigniting.
By dashby - Thursday, January 17, 2013 9:08 AM
Thanks Glenn,

Your info is always appreciated.

BTW, I run a 350 small cam (just playin trucks) and the best milage it will do is 5 1/2 MPG--up hill or down--loaded or empty. Some folks say that is the best it will ever do on milage. Do you agree?

By farmersamm - Monday, January 28, 2013 3:03 AM
Got back to the motor last week.

Got all the new injectors installed with one major disastor. Forgot to tighten #5 and #6. There was a storm coming in, and I just buttoned up the valve cover and walked away from it till the next day. I completely forgot I hadn't tightened the retainers on the injectors. Fired it up a day or so later when I finished adjusting the valves and installing the other injectors, and WHAT A RACKET. One injector was ruined, and the seats were slightly pounded on both. I replaced the ruined one, and lucked out on the seats......they sealed.

Anyhow, the idle is smooth as glass now, and it fires up nicely now. BUT STILL HAS NO POWER.

Before I get into it any further, I thought I'd pass on a little tool tip :)

Setting the valves, crossheads, and injectors, requires holding the adjustment screw tight while torqueing the jamb nut. And in some of the areas there's not enough room for a crows foot wrench adapter for the torque wrench.

Naturally there's a special tool for this Much as this truck has cost me so far, this is simply an added insult. Not gonna spend 250 bucks for a simple tool.

Grab yourself two sockets, actually 4 sockets. Lay out the location for your holes on a piece of 1/4 flat stock.

Cut out the holes, then finish them with a die grinder and carbide burr to a tight fit

Use any type of jig handy, or something cobbled together, to hold the parts for tacking.

Finish weld it. YOU MUST HEAT THE TOOL STEEL TO THE RED STAGE IMMEDIATELY PRIOR TO WELDING IN ORDER TO PREVENT THE WELD FROM CRACKING. I used 7018 because it was what I had on hand. An electrode containing stainless would have been better, but I don't stock it. Tool steel is hard to weld due to the high carbon content, and alloys. 7018 is a good electrode in a pinch because it will readily admix the base metal into the weld pool. You'll anneal the tool steel, but for a low torque application this isn't fatal. As a side note.....welding a piece with such a high temp preheat will cause a difference in the meltoff on your rod, sorta tricky to keep the puddle uniform.

The new adapter in use. Subtract about 5ft lb from the torque specs to compensate for the length of the adapter. Total cost around $18

Anyhow, back to the problem

We finally put a full set of gauges on the truck and ran it down the road under load. I'm hard headed, and it took a while for me to cave in, and do the right thing.

Prior to this I was, unknown to me, using a bad pressure gauge to read boost. This time around I tested a new gauge with a regulator to make sure it was accurate.

Long steep hill, engine lugged down to 1700rpm to simulate a load. Where the engine WOULD top out at 2100rpm (not enough power on most hills) the readings stayed steady in the ranges listed below.

Fuel pressure: 147-155psi steady

Boost Pressure: 10-12psi (I'm thinking this might be ok because this particular engine is an oddball with high compression 17:1, have to find out what the pressure should be) I was expecting something in the 20psi range.

Fuel Inlet Vaccum: 7in THIS IS HIGH. It seems to indicate a restriction in the suction end of the system. I don't fully understand this because I had bypassed the entire system with a temporary line, and it made no difference in the performance. And it has a new filter on it.

Gonna replace all the lines and shutoff valves today, what the's just money :angry: Get the vac readings down, then look at the possible low boost.
By farmersamm - Monday, January 28, 2013 3:23 AM
By Geoff Weeks - Tuesday, January 29, 2013 2:01 PM
17 PSI on the boost if I remember correctly on my 840 CPL. It will go higher with more fuel and a cold day, but not as high as the older Big Cams. My 676 would peg a 30 PSI guage on a cold day, 25-27 on a normal day.
By Geoff Weeks - Tuesday, January 29, 2013 3:07 PM
9670's pull off the rear bottom of the left fuel tank, it is possable something is getting sucked into the fuel fitting/valve. I have pulled off the right tank only in a pinch and didn't notice any power dropoff. I did have some Strato-flex hose go bad, and it acted like a plugged fuel filter. Where are you measureing the suction from?
By farmersamm - Thursday, January 31, 2013 5:28 AM
Geoff Weeks (1/29/2013)
9670's pull off the rear bottom of the left fuel tank, it is possable something is getting sucked into the fuel fitting/valve. I have pulled off the right tank only in a pinch and didn't notice any power dropoff. I did have some Strato-flex hose go bad, and it acted like a plugged fuel filter. Where are you measureing the suction from?

This is the test setup

Fuel pressure is tested at the solenoid plug. Boost is being tested at the aftercooler port. And fuel inlet restriction is tested at a plug AFTER the filter.

It's been suggested that the aftercooler might have an internal air restriction. I have no idea how to determine if this is the case. Any pressure readings would lie I'd think. You can still build air pressure even though a line is restricted. Pressure testing doesn't determine volume I'd think.

Not sure how much more of this I can take. It's causing real stomach problems.
By farmersamm - Thursday, January 31, 2013 5:34 AM
You'd imagine 155psi fuel would make boost.

Obviously, I think LOL, the anneroid is getting sufficient boost signal at 10psi to open and allow 155psi fuel pressure. No air fuel pressure is about half of what it is with an open anneroid.

This HAS to leave an air problem.

Gonna look for a way to pressure the system up and check pressure PRE AFTERCOOLER, and POST AFTERCOOLER. Although this will probably be inconclusive. HUGE SIGH
By Geoff Weeks - Thursday, January 31, 2013 10:17 AM
There is a port on the aftercooler up by the inlet for ether injection, that will be before the cooler core.
By wayne graham - Friday, February 01, 2013 3:07 PM
Geoff, I agree that is the place to test boost pressure. My money is still on the fuel supply to the engine and maybe even in the pump. It takes fuel to make boost and I know that is over simplifying it. Wayne
By glenn akers - Saturday, February 02, 2013 1:58 PM
Samm i think i i may have done said something about the turbo maybe on another site but if you ant check it pull the exhaust pipe off of the turbo and look with a good light and its best to do it in a dark building but look at the turbin wheel and see if the corners of the tips of the wheel is not knocked off. Also give me your engine # and turbo # and let me see if its the right turbo. You dont live for from me.
By kblackav8or - Sunday, February 03, 2013 3:16 AM
Further upstream or downstream? Clogged muffler or exhaust? Clogged or impeded air filter or inlet system? Reading back the focus has mostly been on the engine itself and fuel delivery. Faulty shut off solenoid only opening part way maybe?
By wayne graham - Sunday, February 03, 2013 3:32 AM
One thing for sure, it is time for back to basics. Only 2 ingredients required here,fuel and air and it ain't gettin one of them. Glenn is way more experienced than I so reckon he is the guy. good luck. Wayne
By Geoff Weeks - Sunday, February 03, 2013 5:58 AM
One thing I would check, is the fuel pressure at the head, furthest from the supply, IE the front of the front head. If you have a mjaor fuel resitriction it will show in the fuel pressure at the head, compared to at the pump.
By farmersamm - Monday, February 04, 2013 3:42 AM
Well, more data for what it's worth (shaking head)

Placed a gauge at the aftercooler inlet (Thanks Geoff), put a new filter on it AGAIN, and headed out for a spin

Measured boost at aftercooler inlet-------- 10 to 14 psi. The needle on the gauge fluctuated wildly when boost went above 10psi. It might have reached 15psi but because of the wild fluctuations it was hard to tell.

Measured boost at aftercooler outlet--------- 10-12psi STEADY at full pull from 1500rpms up to 2100rpms. IT HAS TO BE NOTED THAT I HAD TO USE A 30PSI GAUGE ON THE INLET, AND A 60PSI GAUGE ON THE OUTLET, BECAUSE IT WAS ALL I COULD COME UP WITH AT THE HARDWARE STORE IN TOWN. I would imagine the higher psi gauge isn't as sensitive.

Measured fuel pressure----------------- Topped out at 155 every time. Again it seems to get plenty of fuel. I didn't gauge it at the head, it's still at the test port.

Measured fuel inlet vaccum--------------- It's CLIMBING. We maxed out regularly under load at 8.5 inches this time around. It's running around 5 inches just coasting at about 1/2 throttle. I went to Tulsa yesterday to pick up a transfer pump to drain the draw tank in order to replace the line and shutoff valve in this tank. I'll shunt the fuel to the passenger side tank, then refill from it when done.

I should also say that the in-yard performance right after replacing yet another fuel filter was pretty good. Very fast throttle response. When returning from the test run the throttle response had gotten worse.

When, before this, I ran a clear line to the tank (vinyl) we noted a lot of black particles flowing in the fuel uptake. It's concievable that the inside of the old line is deteriorating to the point of clogging the filter very fast. Should know after today when I replace the line and valve. Valve packing is suspect at this point too. It's still odd that the pressure holds steady at full demand even with the restriction in the inlet side of the fuel pump. But it's a glaring test result so I better fix it before moving on to other possible causes.


TURBO NUMBER----Schwitzer 4LHR-753

It would be good to know the normal expected boost for this engine/turbo/CPL
By Kid - Monday, February 04, 2013 5:39 AM
to help Glenn out...


Engine Serial Number11448726
Vehicle ID Number1HSRDGUR0JH589557
Shop Order #SO13827
PlantCEP - Columbus Engine Plant
Build Date21 Jan 1988
Warranty Start Date19 Feb 1988
Customer Number1405
Customer Name
ECM CodeNot Available For This Engine
Fuel Pump Part #3060716
Fuel Pump Calibration4334
Film CardF
Engine Config #D093540BX02
EPA Model Name
Marketing Model NameNTC-FORMULA 350(88NT)
Service Model NameNH/NT 855
By Kid - Monday, February 04, 2013 5:50 AM
SAMM, KW and Pete and NAPA will have the aeroquip hose, but a hydraulic shop might be cheaper.. use #10 , make sure its the big one.. all the wat to the pump..

the old hose may be disintegrating, or, it may be algae in the tanks. Look in with a flashlight, holding tightly, and see how much junk is on the bottom. I'd personally drain it all, steamclean the tanks, and refill with fresh fuel with a quart of BelRey 2 stroke oil one in each tank. Once algae starts, ya gotta clean it ALL out. Could be lots of water from condensation, in the bottom of the tank too.. you should see the bubble of water on the bottom. It will draw water off the bottom first, still show pressure, but be spongy , unresponsive.. not boost cause it aint much fuel. I would drain it ALL, and replace ALL the fuel lines.. and no, I aint rich..
By Kid - Monday, February 04, 2013 6:00 AM
also, dont forgoet to clean or replace that tiny little filter in the top of the pump..
By farmersamm - Monday, February 04, 2013 6:06 AM

Don';t ignore those test gauges!!!!!

Two gauges on passenger side are fuel. Vac, and pressure

Two gauges on drivers side. Boost pressure

As I said, I was gonna fix the vacuum problem before proceeding. I pulled the lines, and the valve on the drivers side where the fuel uptake is.

Looked into the valve outlets.....................and

CAN YOU BELIEVE IT?????!!!!! What are the odds of a piece exactly this size being sucked into the valve??

It's probably been there since I bought the truck, and allowed enough fuel to pull for it to run half decent until it shifted and completely, or almost completely, shut off the fuel to the pump

Life is full of surprises I guess. Gonna put it back together after lunch, and see if it runs.
By farmersamm - Monday, February 04, 2013 11:17 PM Well, it still runs like crap!!

The numbers are there, but it still acts like something isn't getting fed.

Vac dropped to 2-2.5in, fuel pressure remains at 155, and the boost is still running at approximately 14psi.

Throttle response is lazy as usual.

Now I'm gonna look at the exhaust and turbo. The pressure differential between pre aftercooler, and post aftercooler doesn't seem enough to warrant action in that area.

I have an old truck I bought for parts, it has a good muffler on it. Swap it out today and see if the performance changes. I'd just pull the pipe off the turbo but once it's pulled the entire lower half of the exhaust system swings free, not good for a road test.

Speaking of the parts truck. It runs like a raped ape. Fast response, plenty of power..........but the blowby is so bad that it won't run unless the oil filler cap is removed and a rag substituted in the hole. This leads me to believe that the cabover isn't worn out. Besides, it ran in the 70mph range immediately prior to falling on its face, has little blowby, doesn't use oil, etc.

This positively sucks.
By farmersamm - Monday, February 04, 2013 11:20 PM
Geoff suggested testing pressure at the end of the rail, I'll probably do that today too.
By Cam - Thursday, February 07, 2013 1:20 PM
I know I'm no trucker, and I don't know what I'm talking about and etc., etc., but 9 times out of 10 when someone has problems like this, its the fuel tank, lines, filter, or fuel itself. To pin things down, you have to change only one variable at a time. Some guys change 5 things at once, create new problems, maybe fix old ones, etc. I skimmed over this topic, and did see where you have messed some with the fuel system, and found some things.

If I were you-and if you haven't done this yet- I would get a 5 gallon container with a cover, and bungee strap it to the engine on the left side someplace, and run two new and different short fuel lines to and from the pump. Nothing fancy, just an Oilzum can with the two lines shoved into FRESH diesel, fresh from the station. And use two lines which aren't the ones on the truck now. Go around the fuel filter. If it still runs crappy after you completely remove the fuel system from the equation, then it HAS to be something else. But I have been a part of and heard of so many collapsed aeroquip lines, plugged filters, crud IN THE TANK THAT WANDERS OVER THE OUTLET SPORADICALLY, that its usually something simple but elusive like that.

Before I touched the engine, I would do the substitute temporary tank thing. Maybe you've already done it.
By t.c. - Thursday, February 07, 2013 4:27 PM
Next time you run it, turn the thumb screw in on the solenoid. If that doesn't help, check the steel line from the pump to the heads and also the elbow at the back head. Could also be a plugged fuel crossover between the heads.
By wayne graham - Friday, February 08, 2013 1:21 PM
I agree with Cam,back to basics. Wayne
By Geoff Weeks - Friday, February 15, 2013 11:22 AM
Get er licked?
By farmersamm - Tuesday, February 19, 2013 4:36 AM
Sorry for the lag in updates

Being as the boost gauge showed problems, I took a risk and replaced the turbo.

We got a truck engine again!!!!!!!!! Ran it down to Texas to pick up a light load in case it still ran bad. It ran well going down, and had only slight issues coming home.

The engine has always had a slight miss. Now that fuel issues, and boost issues, have been cleared up......the miss is pronounced under heavy boost ie. a load. The miss is accompanied by somewhat lower power when running at around 1900rpm and slightly below. It disappears (not really but is less noticeable) at around 2100rpm. I'm still able to run at about 60-75ish with the fault. But it needs clearing up.

Got a compression tester on the way. Until then I'm gonna pull the injectors and look for any single injector showing excess carbon or crud in the space between the tip and the high pressure cavity, or just a fouled tip. When removing the old injectors the #1 injector was almost completely plugged with crud in the high pressure cavity (the filter screen was partially blocked). At the time I assumed there was crud in the fuel rail, but it may be that there's a problem with tip sealing, allowing combustion products to come up past the injector nose and into the high pressure cavity via the o-ring seal. No crud was found in the upper return cavity, but I'm not happy about possible contaminants possibly finding their way into the return line if the stuff goes up to the upper cavity. I'll probably start with this particular injector.

Was a beautiful place to load now that the rains have come to East Texas. Couldn't ask for a better day I guess.

Only glitch in the trip was the MOTHER OF ALL COOLANT LEAKS. Went thru about 2 gallons going down, and about 3ish gallons coming back up. Doesn't look like a hard fix. Just a little reminder that I'm running stuff long past it's junkyard appointment with destiny. ROFL
By farmersamm - Tuesday, February 19, 2013 4:40 AM
Geoff Weeks (2/15/2013)
Get er licked?

About 90% there Geoff!!
By TonyClemens - Tuesday, February 19, 2013 12:54 PM
How far down in east Texas did you come? Don't see any pine trees in your photos so maybe you came down around Paris or Sulphur Springs?
By farmersamm - Wednesday, February 20, 2013 2:22 AM
TonyClemens (2/19/2013)
How far down in east Texas did you come? Don't see any pine trees in your photos so maybe you came down around Paris or Sulphur Springs?

The hay is located just off Hwy 11 near Pickton. Sulfur Springs is the layover point before I head back up North.

It's a 6hr drive, and what with loading time I can't make the trip in a day without running out of hours. Once I go past 150 air miles I come under log book restrictions even though I'm farm plated (restricted plates).

You know the instant you get back on the Oklahoma side of the line...............the highway goes to Hell in a handbasket. ROFL. We're known for our bad roads here in Oklahoma.
By Cam - Wednesday, February 20, 2013 1:12 PM
What did the turbo impellers look like once you got the old one out?
By farmersamm - Thursday, February 21, 2013 3:21 AM
Cam (2/20/2013)
What did the turbo impellers look like once you got the old one out?

No nicks or damage on the blades. The exhaust side was heavily sooted, and you could see a little oil seepage at the seal.

The huge difference was how the new turbo took the priming oil before first fire up. The old turbo had no backpressure when I filled it with oil using a small syringe. The new turbo required quite a bit of force on the syringe plunger to inject the oil thru the fitting. This says the bearings had a large amount of clearance on the old turbo. I had no really good specs for a runout test on the bearings to actually see how worn they were. I was near the outer limits of the specs I thought applied to this particular turbo when I used a dial gauge.

I did read somewhere that wildly fluctuating boost can be caused by a turbo with loose bearings because the shaft spins erraticly on the cushion of oil due to excessive clearance. This turbo showed very erratic boost at over 10psi, the new one doesn't.

The spool-up time is radically different too, not sluggish anymore. It also now shows around 3psi boost on a snap test sitting in the yard without any load. It's very good now.

I've really felt like a dope on this one, more like a "parts changer" than a rational mechanic. But, then again, there were a host of problems in the system. I've got higher fuel pressure, no restrictions in the intake side of the fuel system, and a fresher turbo now.

To put the truck on a dyno at Cummins would have cost around $250, and they said that they couldn't hook it up to the computer (well duhh!!, it's a mechanical engine). So I don't know if taking it in to a shop would have cost less in the long run. Just the cost of a Genuine Cummins Rebuilt Turbo is around $1300, and that doesn't count the labor. I've replaced the pump, injectors, and turbo, for just over $1700.

Towards the end of this deal I just read the gauges, and took what they were telling me in a simple straightforward way instead of trying to second guess the results and come up with these wild theories by overthinking the problem.

The compression gauge ought to arrive today or tomorrow. Then I'll find the miss. This set is really a good one for me, and a good price. I own Cummins, Detroit, Case, Allis, and Perkins engines, so the adapters in a set are way cheaper than buying them individually. I'd think the price wouldn't be justified for a hobby guy, but the farming operation requires a lotta stuff to keep going without breaking the bank.

1. Test all cylinders

2. If tests ok, then it's a fuel or cam problem(low compression: squirt some motor oil in the cylinder and see if the pressure comes up if so it's a bad ring/liner..........if not it might be a valve or cam)

3. Check the cam lift to see if they're all the same on all cylinders, if checks out ok then it's possibly a defective rebuilt injector

4. The copper sealing seat might be bad on either #5 or #6 because the injectors pounded the seats after the start up when I repaced the injectors (dunno if I put it in this thread, but I forgot to tighten these 2 injectors because I had to hurry and cover the engine up when a rain storm came in, and I forgot to get the stupid things tight the next day). This was just plain old stupidity and forgetfulness. It happens.

5. Then there's gotta be some explanation for the clogged fuel passage in the old #1 injector.

I'm not sure Cummins would have done any better on this one, I'd like to think so. But I've heard some horror stories where the dealer basicly replaces everything on the engine and hands the customer a whopper of a bill. Big Shrug.

Then you have to ask yourself if an old truck is a good investment as opposed to a newer model. I gave around 45-4900 for the truck. I've just put about $4000 into new tires, replaced the suspension the first week I owned it ($2600), spent $1700 on this crap, and about maybe $1000 on misc. stuff. So I'm looking at around $15,000 tied up in an old truck. And that's just parts cost, if I'd paid someone to do it probably at least double the cost maybe.

But I could have dropped somwhere in the 20k range for a newer truck, and faced pretty much the same issues. Anything used is generally worn out when it's put up for sale. You're just buying newer paint. LOL At least I'm facing a known quantity with this truck......I know what's been replaced, and what's maybe going to go bad somewhere down the road. It's a crap shoot I guess

And there's the perverse, in-your-face, pleasure of motoring along in an old piece of iron and keeping up with the newer big boys out on the road. I occassionally get some questions when stopped for fuel or to eat. Usually amazement at the fact it's still on the road, or guys who drove one like it in their youth.

As sort of a side note..........Had I been in a newer truck when the tire blew on the LN9000 I might not have walked away from it. The old larger steering wheels allow for a lot of leverage to keep it on the road. I dunno about the newer trucks with their car-like steering wheels at the new angle (not flat). My left pinkie finger is still almost inoperable from the tendon damage it suffered while holding the wheel in panic mode. ROFLMAO.

I never really liked cabovers when I drove them for a living, and I'm not crazy about them now. I always was a little worried about being THE FIRST ONE AT THE SCENE OF THE ACCIDENT. Nothing between you and what you hit but a thin piece of sheet metal and a windshield. And I'm getting older too......PITA to climb in and out of the thing nowdays. Then the ride is hard on old bones too. But it was the right price, and it's perfect for getting in and out of tight pasture gates and yards.

Try to update this in a few days, right now I'm looking out the window at snow in the yard. I wish I had a shop.
By wayne graham - Thursday, February 21, 2013 7:26 AM
Samm, If you still have a miss at this point then a check on the cam lift is definitely in order. Wayne
By farmersamm - Thursday, February 21, 2013 10:52 AM
Got the goods today via the Fedex dood.

Get started soon as the weather clears tomorrow
By Stretch - Thursday, February 21, 2013 3:30 PM
Wow! You found a tool that's still made in the USA!:hehe:
By wayne graham - Friday, February 22, 2013 6:14 AM
Stretch (2/21/2013)
Wow! You found a tool that's still made in the USA!:hehe:
Ain't that a wonderment. Wayne
By farmersamm - Saturday, February 23, 2013 12:39 AM
As you probably imagine, the Chinese, along with hacking into our most sensitive computer systems, have also copied this tool. It's not a surprise.

How it can be produced, shipped, and retailed, at this price tells you something very important. And I believe, at the risk of sounding like a conspiracy nut, and ethnocentristic hate monger, that it's a general plan to weaken our economy thus leading to weakening of our status as a world power. AND WE ARE HAPPILY PARTICIPATING!!!!!!! The Chinese haven't forced this imported crap on us............It's our own people doing it. Big business is bringing this crap into the country to reap huge profits. "It's just business".

But at the same time, business interests expect to be defended by American blood. It's disgusting.

BTW............OTC has gone the import route too. Look carefully at the newer OTC tools, they're made overseas now. BUT THE PRICE HASN'T COME DOWN.

This process started with the first Volkswagen on the streets in the 70's. It was the begining of the end. I won't drive an import, and have hard feelings against those who do, even at the risk of alienating people. I feel that strongly. And a Toyota "built" in the U.S. is still a Toyota, the profits go overseas.

Got a clear day before the weather sets in again. Probably start the compression and cam tests today.

Tomorrow going to Arkansas for some body parts. IN MY F350 WITH A JAPANESE TRANSMISSION
By farmersamm - Monday, February 25, 2013 2:33 AM
We went and picked up the hood on Sunday.

Pulled outta here at around 7 in the morning, and headed East. K'kins showed admirable bladder control, she's a fine lady.

Great hood for $300. Price some used ones, and see what comes up!! No rust in the hinge area, no cracks, intact hardware mounting areas, and good headlight buckets.

Stopped in Bentonville (Home of Wally World) for some of the best pulled pork I've ever wrapped lips around.


This dood was obviously unhappy about something. Left it parked there.
By wayne graham - Monday, February 25, 2013 3:43 AM
Accusing a used car dealer of being less than honorable. Another wonderment. That is 2 in 1 thread. Gotta be some kind of record. LOL Wayne
By farmersamm - Sunday, March 03, 2013 11:58 AM
Weather finally warmed up enough to get something done on the truck.

Did the compression test today.

Removed all injectors, and installed the dummy injector in each cylinder, and cranked her over.

Very nice tester, easy to use, and holds the pressure very well.

All cylinders tested at 450psi, with one at 425psi, and another at 475ish. They're all close enough to rule out valve or ring/piston/liner problems I believe.

Next step is to determine the cam lift for each injector lobe. I suppose I'll have to reinstall all the injectors and set the preload to do it. Would rather do it without this step, but there's no way I can think of to measure lift unless the pushrod is under load to remove any play. Turning the engine is a breeze without any compression.

If this test proves everything is ok with the cam, it has to be a defective rebuilt injector, or a bad o-ring.

As a side note...........the #1 injector still showed some crud in it after removal. I might try to run some air pressure thru the head to clear out any crud in the fuel passage supplying this injector. #1 cylinder is the only one still below temp when measured with an infrared thermometer.
By farmersamm - Monday, March 04, 2013 2:03 AM Just occurred to me................I can use the injector timing tool to measure cam lift WITHOUT setting up an indicator on the injector plungers Don't have to reinstall injectors this way.

Never trust anything to an idiot.
By farmersamm - Monday, March 04, 2013 11:03 AM
Was able to do the cam testing today.

I didn't check injector timing, just lift at each lobe

#1 .183

#2 .186

#3 .185

#4 .174

#5 .185

#6 .178

I don't know the original specs, but my feeling is that I'm not showing anything critical here. I had thought to possibly find a really flat lobe which would not have enough pushrod travel to supply one or more cylinders with adequate fuel.

Although the cylinders might not getting a balanced fuel charge, they will get fuel according to the test.........if the remaining components are functioning.

Now it's on to the fuel passages, and injector function. I'd positively crap if one of the "new" injectors is no good
By farmersamm - Wednesday, March 06, 2013 11:48 PM
Finally came to a resolution on the deal.

Removed all injectors to do the cam lobe test ya know. Put it all back together to find the miss by de-activating the injectors one-at-a-time.

As usual the thing was vibrating like a coffee grinder.

Had it running with the valve covers off, and was standing on the spring to give it the "look". You know, the look everyone gives the motor when they can't figure out what's wrong. You see countless doooods looking forlornly under the hood on the side of the road.

Then I heard it. A chuffing sound. It was coming from the middle head so I thought.

To isolate the source of the noise I used shop rags to cover the entire valve train in order to block the sound of all the valves, then removed the rags from the top of each cylinder, while leaving the rags on the other cylinders. It worked. Number 3 cylinder was leaking compression through the injector.

Replaced the injector with another spare, and it's smooth.

The rebuilt injectors came from Pro Diesel. I'm not happy with the product as you can imagine. Looking at the brass footprint on the nose of the injector you can see that the sealing was along the entire length of the tip, not just around a small band. This doesn't work, it has to be a sharp corner seal, so to speak.

Had I bought the injectors from Cummins it might have been different, but there's no telling.

So, after all's said and done...........I'm apparently in good shape. BUT I STILL NEED A CAM AND RELATED COMPONENTS. I can live with this for now. The truck needs to be back in service.

I feel that the engine has been derated due to the worn cam, and it will have to do for now. Cam lobe wear has resulted in less fuel delivery to the cylinder. Injector plunger travel isn't to the max. This would account for the less than optimal boost, although the new turbo bought me another 5lbs of wind.

New water pump gasket, new drive axle seal, new trailer tire, and it's back down to Texas again.

Thought I'd leave ya with this bit of wisdom, and insight.