She ran away

[timntrucks]

lets hope it all comes out for the best WM good luck

 

[Crash_AF]

Even if the engine were totally full of fuel...like the crankcase full enough to be running out the valve covers....WAIT, that could be the issue! There was an issue with the fuel system that filled the engine with fuel...close to or above the level of the top of the heads. Naturally asperated Cummins heads have a hole in the head that goes directly into the intake. This was/is there to suck some of the crankcase vapors back into the engine...it's an emissions thing. The fuel source was sucked into the intake by the vacuum in the intake through the vent holes.
Wrecker, how much oil is left in it?

Yea, I think that's what happened. The seals on the injectors failed, pumping the crankcase full of fuel or the one of the heads cracked allowing the fuel passage to leak into the crankcase.

Hopefully the shut down was quick enough to prevent any MAJOR damage from occurring.

Later,
Joe

 

[rosco]

I have seen vehicles "slow idle" for long periods of time, especially in winter where they are running too cold , not up to temperature, that have severly diluted the crankcase oil. Low compression contributes. The stack shows signs of this. In a DD, much will accumulate in the air box & can cause a runaway. Poor engine condition, excessive idlying, little of no maintance, could cause the above.

Lee in Alaska

 

[FreightTrain]

well,this thing has about 20 gallons in the crank case plus the 3 or 4 gallons across 20 acres so.I got a feeling it was either a crack in teh head or O rings.Thinking O rings.

 

[LOGGJAM]

Hey all I had the runaway diesel issue (panic!) a few times on older Mack engines 673 cu in diesels. I always got the piece of plywood near by when starting engines that were sitting for a while, run-away usually occurs with rack being stuck in the full fuel position or high oil level in the crankcase caused by oil dillution from leaky/slobbering injectors or excessive idle time. As precautions i like to put a fuel shut off valve/ball valve on the fuel supply line to the injection pump or IP head works great if its a fuel runaway, but for an lube oil runaway in the case of high oil level or turbo seals ya gotta cut the air supply, i have also stopped them by putting the trans in the highest gear and using the clutch to stop them providing that it is not already way past its governed speed, for my deuce i have a rubber bag that fits over the mushroom, and can be squeezed tight around the intake pipe with a zip tie, never had the issue with the deuce but i tried it with the engine at ~1800 RPMS and it stops in a few seconds,

Good luck

Mike

 

[HSFDChief600]

I do know that the Multi-fueled engines could lope hard on shutoff and run backwards. It would black smoke and throw oil out the stack. We had an incident with our tanker some years back when one of my guys had shut the truck off to talk to me and when he re-fired it and tried to pull off it went backwards. The look on his face was priceless as he kept saying Im in first im in first but I keep going backwards. It had just started to black smoke when I told him to shut it down and re start it. IT smoked for just until it burned the oil out of the stack, we did have alot of oil to clean up off of our pad.

 

[WillWagner]

A 250 Cummins doesn't have a rack to stick. The fuel pump supplies constant pressure and the injectors fire off the rocker arms. There is a governor in the pump so I guess it could stick.

Nah, there's just a plunger inside..all the pump internals are fuel bathed. When the governor plunger sticks, it's just like putting a stinger in the pump, it will operate normally but will go WAY past the governed speed, fuel pressure gues accordingly with engine RPM, or will have lower than normal speed or won't start. A PT pump won't cause a run away. The high oil/fuel level in the pan caused it. It just slurped the oil right thru the vent holes in the heads.
WM, how much RPM you think it turned? I've seen them turn 4k and live. They get real smooth and quiet at speeds above 3000.
Check the tank vent. Since the tanks are lower than the engine that could be your issue. There are two passages on the injectors, 3 orings. The lower is the supply pressure..120 PSI or so, loaded, unless you jacked the pressure up. The upper passage is the return, no pressure there. The fuel just dribbles out of it and gravity feeds back to the tank. The old orings weren't viton, so they got real hard and flattened out, usually the only indication of this was a no start after a shut down, but sometimes there is a fuel in the oil or a black fuel issue. That came from the top oring being hard and flat/cracked and the oil that sloshes around up top, migrates into the return fuel passage and contaminates the fuel. Just an FYI, there is no fuel pressure at idle, only flow, so the pump couldn't have pumped all the fuel into the oil at an idle speed. It could have filled the CC the last time you drove it. You would have noticed a big power loss due to the fuel pressure being shunted past the orings and into the oil.
Keep us posted on your findings, i'm very curious to see what the cause was. I hope it didn't get hurt.

 

[doghead]

FT had said something about it running on a temporary fuel tank and not the original fuel tank. I am wondering about that.

 

[WillWagner]

Well, if it is mounted higher than the engine, that could do it.

 

[FreightTrain]

yea,it is mounted on the bed behind the cab up on 4x4 blocks so it is WAY higher than the engine.

 

[doghead]

I think the "mystery" is solved. It sounds like, WM's alter ego Mr Murphy, has reared his ugly head..

This whole episode, is a great lesson for everyone, to check your fluid levels Before starting your truck.

 

[Bohica82]

When I was stationed in Korea I had a runaway engine on a M816 also. We had a HEMMT wrecker that got most of the work so the 5T sat alot of the time. So when 2 new guys got to Korea at the same time we tried to get it running. Someone before us "worked on it", namely messing with the Fuel Injector Pump as it wasn't getting any fuel. Turns out is was the fuel hoses were dry-rotted on the change over valve for the L and R tanks behind the drivers seat. So we got those changed and got it started, didn't take long to run away. I remember getting it outside the bays, vise gripping the fuel line and putting something over the intake but it wouldn't stop only lope along which is better than the 3100 or so RPM that it was doing at full tilt. It had alternating oily black smoke and white smoke. Made for an exciting end of day fix. After a new IP it ran just fine. Still used the HEMMT for most everyting though since it is a HEMMT.

 

[FreightTrain]

you know.I shouldn't have told the M816 the fate of every other Green machine that has set foot on the property.......That might have been the cause.Tried to commite suicide before wrecker could get out the red wrench.

 

[timntrucks]

red wrench... that one is new... anyway has he tried to find out if the engine is toast?

 

[rockman]

WR, great response to your runaway. What was gooing on that it sucked oil?

 

[rwelker]

My M810 when I got it had not been run for years the way it looked. I put fuel in it; bled everything and then we pulled it to start. It started easily; idled nicely until I "stabbed" the throttle and it ran away. I shut it off with the emergency shut off cable. Took off the pump; had it rebuilt. The shop said while it was clean, all the seals were shot and it had a "sticky" govener. It's been fine since. All I did was rebuild the pump; oil level and everything was the same (the oil was not diluted and not overfull when it ran away). I just had a duece do the same; I have not had a chance to take a look at the rack as of yet but when I started it I pinched off the fuel lines going into the filters before I started it. It quickly ran out of fuel when it "ran away" and stopped after about 2 seconds.

 

[ARMYMAN30YearsPlus]

Wow all the good information on what I should look out for when I get home from almost two years in Korea. Also I am looking at moving to southern Georgia where the state is red and the Bible is still a best read book.

 

[FreightTrain]

Heck,Come over here to Alabama!Maybe we can find a large peice of land and split it in half.Save us both some money and know atleast we have good nieghbors on one side.....

 

[AKJEEP]

so how badly does it flood out the engine when you have to kill it that way?

 

[alphadeltaromeo]

Wow all the good information on what I should look out for when I get home from almost two years in Korea. Also I am looking at moving to southern Georgia where the state is red and the Bible is still a best read book.

GA is a good State...you'll like it. Living here will make it much easier to go to the GA/FL Rally's for sure! (no comments about me missing them)