M35A2 runaway problem

Question while on the subject...
New fuel tank
New in tank pump
New injector lines
New HH
New filters
No intake heater
Fuel shut off isn't sticking
100% diesel in tank
Replaced all of this due to sludge and a bad HH...we got the unit started, idled great...then we gave it a little fuel (from the pedal?) Then the idle....just kept on going up....peaked at about 2700rpm...
Back story.... unit sat for a few years from a lack of fuel (HH) Think someone fondled the governor...there was some schlack in the HH from old fuel....
***YES I'VE LOOKED AT THE TM's***

If it's not getting the excess fuel from the IP, and no flame heater, the other fuel source it could potentialy draw from is crankcase oil through leaky turbo seals (as cattlerepairman stated). You can check by pulling the little hose section from the front of the turbo and looking at the compressor wheel... is it wet? does it have excessive side-to-side or front-to-back play? Out of curiosity, how's your oil level? does the oil seem fuel-diluted at all? with the truck not running, and the master switch on, can you hear fuel getting returned back to the tank?

Menaces Nemesis said:

If it's not getting the excess fuel from the IP, and no flame heater, the other fuel source it could potentialy draw from is crankcase oil through leaky turbo seals. You can check by pulling the little hose section from the front of the turbo and looking at the compressor wheel... is it wet? does it have excessive side-to-side or front-to-back play? Out of curiosity, how's your oil level? does the oil seem fuel-diluted at all? with the truck not running, and the master switch on, can you hear fuel getting returned back to the tank?

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Just changed the oil 2 days ago...the old oil had no hint of fuel. Ill go out and check the impeller on the turbo this afternoon and will for fuel returning and oil tomorrow.

DanoBonanno said:

Just changed the oil 2 days ago...the old oil had no hint of fuel. Ill go out and check the impeller on the turbo this afternoon and will for fuel returning and oil tomorrow.

Click to expand...

Also...we had the piping off of the front of the turbo and that part was dry

Is the freakin springs broke?
Just sayin, silly stuff

They only put one as it was not expected to last very long.

frank8003 said:

Is the freakin springs broke?
Just sayin, silly stuff

They only put one as it was not expected to last very long.

Click to expand...

Lol, springs are good...pedal returns. I know what you mean, sometimes it could be something simple

cattlerepairman said:

Do yourself a favour and make the temporary fix your permanent fix. Remove the complete flame heater setup and plug the connections. Unless you regularly fire her up in well below freezing you don't need it and if you do need regular cold start help, spring for a KAT 24V ether dispenser that shoots a metered dose into the intake. The flame heater is nice and nostalgic if it works properly and does not leak, but a PITA (as you found out) when it doesn't work right.

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Hey, I liked my flame heater stuff, never know where I might go. It came with it and belongs in it and will maintain it.

DanoBonanno said:

Just changed the oil 2 days ago...the old oil had no hint of fuel. Ill go out and check the impeller on the turbo this afternoon and will for fuel returning and oil tomorrow.

Click to expand...

**just checked the turbo....impeller is smooth and no play, took the piping off...looks normal

DanoBonanno said:

Question while on the subject...
New fuel tank
New in tank pump
New injector lines
New HH
New filters
No intake heater
Fuel shut off isn't sticking
100% diesel in tank
Replaced all of this due to sludge and a bad HH...we got the unit started, idled great...then we gave it a little fuel (from the pedal?) Then the idle....just kept on going up....peaked at about 2700rpm...
Back story.... unit sat for a few years from a lack of fuel (HH) Think someone fondled the governor...there was some schlack in the HH from old fuel....
***YES I'VE LOOKED AT THE TM's***

Click to expand...

Just to be clear you took the two screws out of the timing cover, some call it the shut down cover and you made sure the fuel control unit assembly was moving free. With motor off it should look like just about the 7 o'clock position and with your finger you can push it back to to about the 4 o' clock position. Then it will snap back to the 7 o'clock when you let it go?

Were you able to get this resolved?

I am having a similar "runaway issue" under the same circumstances i.e. fuel control arm is moving free, flame heater is deleted, new fuel pump/filters, etc.. Truck idles good for a bit then starts smoking bad and revs up well out of normal operating range. The fuel shutoff works, but will not stop it when it starts to run away (I tested the cutoff with fuel lines disconnected and it cuts the fuel off to the HH). I have to have someone on the air intake to shut it down while I try to troubleshoot.

Pistol817 said:

Were you able to get this resolved?

I am having a similar "runaway issue" under the same circumstances i.e. fuel control arm is moving free, flame heater is deleted, new fuel pump/filters, etc.. Truck idles good for a bit then starts smoking bad and revs up well out of normal operating range. The fuel shutoff works, but will not stop it when it starts to run away (I tested the cutoff with fuel lines disconnected and it cuts the fuel off to the HH). I have to have someone on the air intake to shut it down while I try to troubleshoot.

Click to expand...

The smoking and the fuel shutoff not working, immediately suggest an alternative fuel source - i.e. crankcase oil. In most cases, leaky turbo oil seals allow the engine to suck oil into the intake through this pathway. If that is the case, closing off the air supply is the only way to stop the engine. I am by no means an expert on runaway Deuces, but that is where I'd look first.

Alternatively, on the other end of the spectrum of unlikely situations, you have a punctured natural gas or propane line near where the truck is parked and it runs away on the gas saturated air it breathes in! (I remember reading about an excavator doing that after the operator punctured a natural gas line).

That was my first thought as well, the turbo leaking into the intake.

"Sent w/o me knowing"

I pulled the curve part off the intake on the downstream side of the turbo. It does look there is some black motor oil in there and in the turbo. The turbo doesn't seem to have any slack in it. How would be the best way to repair the issue? May be just replace the turbo, or can seals be replaced?

Does it leak on the exhaust side also?

The "oil seals" or "shaft seals" are actually quite hard metal "slingers" that throw oil away from the shaft, rather than what one would think of when mentioning "shaft seals".

If this was my truck, and it had started smoking after a lot of idling, I'd clean the oil up and then run it hard on the highway for half an hour. Chances are that the mess cleans itself up and the seals are back to doing the sealing.
If you do not idle your truck and the smoke show did not start after prolonged idling, I'd be more cautious. If your engine tends to run away, regardless, and can only be controlled by blocking the air intake, I'd say you are past trying this approach!

Time to replace the turbo. I am not sure what you have, C or D.

I know that people here have disassembled the C- turbo (Schwitzer) and rebuilt it; I am not sure if I would....they are kinda picky about balance and I can't see how I could balance a turbo at home in a way that makes me comfortable. Anyhooo...your mileage may vary. Get the part number of your turbo to be certain what you have and check for rebuild kits if you want go that route.

I disconnected the intake from the turbo. Had to bleed the injectors again as it had lost its prime I guess.

Turbo disconnected and no way for an alternative fuel source. The truck still fires up with the same symptoms. Pours black smoke and goes screaming wide open. The only way to regulate rpms is by regulating air at the intake.

When it’s running the fuel idle/cut off arm is in the full off position (3:30/4:00 position). Moving the fuel shutoff has no effect on how it runs.

If the tiny brass clip comes loose from the “fuel shutoff” inside the hydraulic head. Would that cause the issue? When I put it back together, and pulled the cutoff, the fuel flow stopped. Is it possible it could have come off after it started.

Is there anyone near Corsicana, TX that works on these?

Possible you've got the fuel control unit assembly installed incorrectly or the timing shutdown rod cover?

I think I got it figured out. The throttle pin for the fuel shut off was broken. Inexperience I guess. I didn’t realize it had a longer shaft until I took the one out of another pump I have. I could get it to stay for a little while, then it would come loose and there was no way to stop it.