M923A1 was broken down.

sd39u · Apr 10, 2015

I was taking my M923A1 to the barn this afternoon when the truck began to lose power and eventually died on me. The engine hot light was illuminated but the temp gauge only showed 190. After waiting about 10-12 minutes, it started back up. About 1 mile from my destination, same thing happened again, only this time it would not fire back up.

Engine hot light was illuminated, temp gauge was pegged at 240. While driving the temp gauge never went above 190. It simply wouldn't crank. No fluids leaking. No smoke. Lots of heat waves were visible.

A local farmer shoved me with his tractor to my destination before I ran outta air. Stroke of luck there.

I won't be able to get back down to the barn until Sunday. Best case scenario...I'm hoping it's the thermostat stuck in the closed position. Worst case scenario...I seized the motor.

I think I'm on the right track. Any other suggestions?

Eric

Tow4 · Apr 11, 2015

If you think the motor is seized, barr the engine over to make sure it's not seized before you try to start it. The starter solenoid can stick under the high current load it will see if the engine is locked and then you have an electrical melt down and potential fire/battery explosion to deal with.

http://www.steelsoldiers.com/showthread.php?121343-Engine-Barring-Tool&highlight=barring

Monkeyboyarmy · Apr 11, 2015

I think you got lucky the first time. Was the coolant level OK?

gimpyrobb · Apr 11, 2015

Yup, I'd start with checking fluids.

How far total was the trip?

MWMULES · Apr 11, 2015

sd39u had to go out of town early this AM and if he gets back in time tomorrow, I'll go down to the barn with him to see if we can get this figured out. Been reading up on the 939 fan actuator and clutch so I have an idea of what may have gone south. Those are the major differences in the M939A1 cooling that I can think of versus the 250 in my XM818 , correct?

sd39u · Apr 11, 2015

About a 30 mile trip. Coolant levels and fluid levels were all checked on last Saturday.

R Racing · Apr 11, 2015

Check your fuel filter and fuel lines. Mine did something simular when my filter got clogged in my m813.

porkysplace · Apr 11, 2015

sd39u said:
About a 30 mile trip. Coolant levels and fluid levels were all checked on last Saturday.

What did the oil look like after it shut down , was it over full ? 6 days would give a internal coolant plenty of time to leak into the oil .

sd39u · Apr 11, 2015

Oil was black. Not milky.

No oil in coolant either. Coolant was greenish/orange.

I could see fuel in the clear tube from the primer pump to the injector pump.

sd39u · Apr 11, 2015

I should add...truck performed flawlessly on 2 45 mile trips on Monday to/from Kaufmann Stadium. No issues. Heater was working that AM and the temp of the motor never got above about 165 on that trip. It was rainy/wet.

I drove the truck to work on Thursday...18 miles in and 18 back. No issues.

Baradium · Apr 11, 2015

Presence of fuel might not neccessarily indicate enough of it to run. I don't suppose you opened the hood and put your hand near the motor to see exactly how hot the motor felt? With electric temperature guages it could still potentially be an electrical reason that you saw the high reading.

sd39u · Apr 11, 2015

Oh...it was hot...I could see the heat waves and feel the heat!

R Racing · Apr 11, 2015

The engine could run hot if it runs lean from lack of fuel. Pull the fuel filter and see how it looks.

bchauvette · Apr 11, 2015

did the fan clutch engage? If it didn't there is a bolt parked near the clutch that you can install to keep the fan engaged.

Baradium · Apr 12, 2015

R Racing said:
The engine could run hot if it runs lean from lack of fuel. Pull the fuel filter and see how it looks.

Diesel engines don't really run lean. Or more precisely, they are always running as lean as they can since airflow isn't regulated, only fuel flow.

bchauvette · Apr 12, 2015

Baradium said:
Diesel engines don't really run lean. Or more precisely, they are always running as lean as they can since airflow isn't regulated, only fuel flow.

I understand that there are systems that regulate fuel flow to load to rpm. There is probable a bad ass word for this. If when you stomped the accelerator and if the flow was immediately maxed you'd get all kinds of black smoke. So the adjustment for all this is where you would get the lean condition. But all of this is academic in this situation as it doesn't look like he was running under any appreciable load.

Still looking for the fan clutch answer.

sd39u · Apr 12, 2015

I had a chance to swing by the truck on the way home from Tulsa...flipped on the battery switch...tried to start it and it just clicked. It clicked with authority...but it wouldn't crank over.

It's gonna be Tuesday before I have another chance to get down there with some tools. I'm hoping a couple of local KC experts can meet/join me to help diagnose and hopefully fix/correct the issues.

Thanks to everyone for all the help so far. It's a been a long weekend at my kids soccer tourney thinking about what it could be and reading a few tech manuals in between games on my iPad.

Eric

sd39u · Apr 14, 2015

Headed down south with MWMules and a couple of other friends.

We worked on the truck for a few hours, no luck getting it to crank over. Batteries are good. Engine still has nice green coolant. We tried to use a cheater pipe and a socket to turn the crankshaft over...no luck.

Next step...diesel truck shop about 10miles away. May have to tow it there and get it looked at. Not giving up yet!

Eric

sd39u · May 13, 2015

Well...the verdict is finally in. The motor is seized. Big Dog is DEAD.

Frustrating...but another lesson learned.

Eric.

6x6guy · May 14, 2015

Was it determined why the engine seized, with the cause and affect theory.

M923A1 was broken down.

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