Engine Locked? | 855 Cummins

[Zoidsfan77]

Engine Locked Up? | 855 Cummins

Greetings! Sad times hath befallen.
Today I went to start my M814 with the NHC 250 Cummins. It turned over, and began to start. It spat a good deal of white smoke, but not anything to out of the ordinary for this truck. I felt the engine was running, and disengaged the starter. About one or two seconds later, the engine just stops. Not the usual coast down to a stop, it stopped immediately. I waited a minute, then hit the starter again, nothing. Would not budge.

So, I opened the hood, removed all the rocker covers, and barred the engine over by hand to see if I could find anything really suspect. It actually turns pretty freely, except for one hard spot.

As some of you may recall, I just did the overhead on this truck, and although it did run and drive since, it was only once, just after I finished. The truck has sat for some time since, a week perhaps.
That thread is here: http://www.steelsoldiers.com/showthread.php?163532-To-Purge-or-Not-to-Purge-855-Cummins

So I am kind of bummed out. I really hope it didn't hydrolock and bend a connecting rod. Best case I guess is that I set the overhead wrong, and an injector is damaged.
But I did drive it once since setting the overhead, and it drove about the same as before (low power).

Those of you with experience, what would you do next?

 

[doghead]

Look for a dropped or stuck valve.

If a valve hit a piston, you'll need to pull the pan and look for piston damage.

 

[Zoidsfan77]

Thanks doghead. Is it possible to identify a stuck valve without pulling the heads or valvesprings?
I barred the engine over while watching the valvesprings and didn't see anything unusual.

Additionally, I loosened up all injector adjustment screws. There is still no change in engine rotation that I can notice. It seems to bind when I start approaching any of the VS marks, VS 3-4 especially it seems.

 

[doghead]

You can try tapping the valves with a plastic hammer, but unless it stays down this is not a great way to find it especially if you already have a bent valve(it will return but it will be lower than the others).

Most likely you will need to remove the heads.

 

[Zoidsfan77]

That is unfortunate, but I suppose new headgaskets wouldn't hurt anyway, as it does leak oil slightly.

I am going to wait to pull the heads just yet, but I will order gaskets.

Doing "major" engine work is not easy in my case, as it must be done outdoors without the assistance of any lifts or hoists. All I got is a 2 car garage that is so packed you couldn't park a lawnmower in there.

 

[snowtrac nome]

I would doubt it is a valve problem unless you broke a head off I have seen that sounds like a fluid lock, fuel or coolant

 

[WillWagner]

Pull the injectors out of it. Any liquid coming out of the exhaust manifold joints?
A stuck injector won't lock the engine. If it didn't make a banging noise it is most likely fluid. You said it barred over, that means it ain't stuck. Maybe try and start it again and listen to the noise in the intake and exhaust.

 

[Zoidsfan77]

I will look at the TMs for info on how to pull the injectors, per Wills advice. Do I need a special tool? The 34 TM suggests I do.
No liquids from exhaust piping that I can see.

No unusual noises, it started, ran for a few seconds, then suddenly stopped. No bang.

If it is fluid, what are the odds I have bent a connecting rod? What is the easiest way to check?

Thank you all for your advice!

 

[Scar59]

Drain and pull the oil pan, you will be able to look up into the cylinders.

 

[doghead]

This is what a piston looks like after it touches a valve.

I guess you can't see it in the pics but, the piston is cracked near the edge and it barred over hard when the piston was at the top.

In this case, an adjuster came loose and the valve touched the piston.

 

[dmetalmiki]

Thanks doghead. Is it possible to identify a stuck valve without pulling the heads or valvesprings?
I barred the engine over while watching the valvesprings and didn't see anything unusual.

Additionally, I loosened up all injector adjustment screws. There is still no change in engine rotation that I can notice. It seems to bind when I start approaching any of the VS marks, VS 3-4 especially it seems.

Well if all is working inside the engine and you have not removed or released compressions, then it will be 'tight' as each piston comes up on compressions. I would take off the heads and replace those gaskets, and really check the timing properly. (you are 'worrying about a bent rod') but nothing will be striking as logically the piston travels less distance with a bent rod. So in addition check Piston Travel at the time the heads are off. keep us informed.

 

[red]

Slow down, not guaranteed that you need to pull the heads yet yall are jumping the gun.

Pull the valve covers and measure the length of each valve. Rotate the engine over so every valve is measured when it's open, and when it's closed. If one is shorter than the others than that valve is bent.

If none of the valves measure short then remove the injectors and get your hands on a endoscope. Might be able to rent one from a local autoparts store or can get a cheap one online for about $50. With that you can stick the scope down through the injector hole and get a look at each combustion chamber. Inside of the head, piston, valves, etc. Something is damaged it will be pretty clear. Again you will need to rotate the motor over to get a good view of everything.

 

[Jbulach]

Have we even ruled out the starting system yet??? If you can turn it over by hand, the starter should crank it...


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[Zoidsfan77]

A starting system problem wouldn't cause it to stop (and so suddenly) after it was running.
However, after about an hour of troubleshooting, I tried to turn it over with the starter again, only to find the battery was low (needle buried in red on voltmeter). So I can't really rule it out I suppose. When it failed to start the first time, the voltmeter needle was just into the yellow, but it did have somewhat of a hard time cranking. That could just be due to some other problem, whether it be valve, fluid, etc.
I still want to at least pull the oil pan, even if only for peice of mind. If it still won't start after that and charging up the batteries, or starts but I don't feel like everything is OK, I will pull the heads for sure.

Oh also, I do actually have a couple cheap endoscopes ($15 each, they are not bad actually, especially for the price!). If I pull the injectors, which I think I really should, as my current ones are a bit suspect anyway (still low power after injector adjustment), I will peer down there with the scope and see if I can see anything.

Thank you all so much for sharing your wisdom and advice. This forum has an excellent community.

 

[Tow4]

I had a similar event several years ago with an M818. I had just started the truck and shut it off to do something. When I went to start it again the starter sounded like the engine was locked. The battery voltages were OK. The next day I barred the engine over expecting it to be locked and it turned over. I rechecked the batteries with a load tester and 2 were bad and had evidently failed suddenly.

I would replace the batteries or slave it and see if it starts.

 

[Swamp Donkey]

A starting system problem wouldn't cause it to stop (and so suddenly) after it was running.

A fuel shut-off solenoid that isn't getting enough power, due to drained batteries, will though. With your other recent problems I know you've done a lot of cranking. A starter doesn't work well with drained batteries either. Check and charge the batteries first. You're going at this backwards.

 

[big block 88]

^^^^^^x2. Why not stop and do a proper diagnostic before rippin it apart?

Check the bats and charging system and fuel shut off. Then the starter, and its your truck man but i would sure scope the bores before i decided to just yank the heads just because maybe there might be something wrong internally.

 

[Zoidsfan77]

You are correct. Jumping to conclusions has bitten me in the past, so it may be wise to do a little sit-rep before tearing into things. All I have done thus far, is remove the rocker covers, loosen the injector adjustment screws (and recently reset them back to proper torques), and bar the engine over.
I have not been able to contribute to this forum as much as I would like, at least not yet. I like to think if I can provide as much value as I have received, then I am a being a good member of this community. I have yet to reach that point. I can at least try to do a good job in my documentation, so as to best help those who come later.If you are that person, here is where I am at:
Facts:

• Overhead recently adjusted.
• Engine stopped suddenly 5-10 seconds after startup.
• Prior to startup, glow-plug was activated, and I gave 2-3 pumps on the primer lever.
• Engine stop was much more abrupt than usual. There was no abnormal noise.
• Starter unable to turn engine over.
• Engine bars over by hand, with a few tougher spots.
• Voltmeter read OK (top end of yellow) before startup, now reads low.
• Batteries are now low.
• Batteries are now unable to supply enough power to properly engage starter.
• Engine seemed to crank slightly slower for startup.
• Emergency fuel cutoff valve non-operational. Lever difficult to turn, does not affect engine operation when tested with engine running in the past.
• Truck is parked nose up on a slight incline.
• Truck has suffered from low power since I have owned it.
• Fuel filters and filter-pump fuel line replaced recently with spin-on variety. Driven a fair bit since. Old fuel line interior seemed dirty.
• Truck is parked next to another, smaller vehicle. Vehicle is covered by tarp. Tarp has numerous small drops of black liquid on its surface, from exhaust of truck.
• Last time the truck was driven, it was driven in two 20 minute trips, about 1 hour apart. When starting engine between trips, starter slow to crank. Took two cranks to start. This was the last time the truck was started successfully.
• Voltmeter read in green when truck was running last.
• Batteries are not the 4 stock military ones, but rather a set of 2 Duracell commercial civilian batteries.
• Batteries purchased December 1st, 2016, and installed when I purchased the vehicle, by the previous owner.
• Seam between block and heads moist with oil, rearmost head especially.
• Batteries are now disconnected.

The facts do lend themselves to the problem being electrical. This does not explain why the engine stopped so suddenly. Usually, when I flip the switch to shut down, the engine continues to turn a fair bit before stopping. When coming to a stop, it rocks back and forth a bit. This time, it was running, then suddenly silence.

Thank you all.

 

[autoshopteacher]

Interesting thread, lots of good ideas.
Step one of any engine troubleshooting should be to have fully charged known good batteries. After charging, load test. 12 volt battery is fully charged at 12.6 VDC. Load test to one half the CCA for 15 seconds. At 70 degrees F the voltage should not drop below 9.6 VDC. Colder batteries can drop slightly below 9.6 but probably not as low as 8 VDC below 30 degrees F. There are other tests but this one is very good.

 

[WillWagner]

A FSOV won't cause an abrupt stop. Put some life in the batteries. Is the oil level over full? If not, no slobber from the joints, coolant not low, you can turn it by barring it. Try and start it. I have seen starters come apart and lock the engine up.