NHC250 foreign object in cylinder.

[Ferroequinologist]

Well I picked up this beautiful M931a1 for a former member here last Jan. 9.8 miles on the clock. Very nice truck. Drive shafts disconnected. Warning #1. Got it home and charged the batteries. Starter would just go CLUNK. Warning #2. Tried to bar the engine over. Wouldn't turn in either direction. Warning #3. Started pulling rocker boxes and injectors to see if she is hydrolocked. Number two looks very funny.

So anyway I pulled the head this weekend, and found this. Looks like something got into or was left after rebuild the #2 cylinder. It beat the tar out of it until the piston started to come apart in chunks. There is even a piece of ring in the top of the piston because the side of the piston is so bad. Melted aluminum everywhere. Engine is locked up hard. Worst part about all this, is you have to rotate the engine to take the torque converter off. So I will have to tip the engine onto its side and take the lower end loose to get the rear off. He purchased another 250 to go into it I just have to swap all the parts over.

Thought you guys would like to see the carnage. Some of the piston pieces even made it into the #1 cylinder.

 

[juanprado]

Where was it rebuilt?

 

[Ferroequinologist]

I believe Toole. I will look again tomorrow.

 

[Jim Timber]

Not possible to replace the sleeve, piston, and head? Might be easier than swapping the engines.

 

[Suprman]

Could it have ate a piston ring. Too much ether can do that.

 

[m16ty]

I wonder if the injector on that cylinder was messed up and caused that cylinder to overheat instead of a foreign object?

 

[wreckerman893]

Fubar.

 

[Ferroequinologist]

I thought of that Ty, but there is obvious ding marks in the top of the piston and in the head. Could be the dings in the head are from the piece of ring, but I pried it out so I'm not sure if it was free floating or not. The injectors all 'appear' fine. I know you can't really tell without pop testing however. The exhaust manifold is not nearly as sooty for #2 compared to the rest, and its not just the fact it has a coating of aluminum powder lol. Me thinks the piston started to come apart pretty quickly and plugged up the injector. There is actually a tight metal bowl over the injector hole with the imprint of an injector in the top. That would have either sealed off or at least messed up the spray and compounded the problem.

Yes, you 'should' be able to replace a piston and sleeve. (actually two, as the #1 got damaged as well) Engine might be rebuildable but for what a used 250 goes for not much in the way of cheaper.

 

[Jim Timber]

I'm just thinking it's easier to drop the pan than to pull the engine. I suppose if you have a capable crane it's not though.

 

[Ferroequinologist]

Had the engine out in under 2hr

It's been this freaky weather, and other life things that are making it take forever to swap the parts onto the new engine and put it all back in.

 

[Jim Timber]

Yeah, this winter has been nuts. We're getting 40F tomorrow after 45 days with below zero temps this winter. Average temp this time of year should be mid 20's - we've been lucky to see double digits! But that warm spell is short lived - high for Sunday is 2.

 

[Jeepsinker]

You guys can keep that stuff up there with you. I don't want anymore of it.

 

[Rifleman]

Could the injector or injector feed for that cylinder of gotten restricted or plugged, to the point were it cut the fuel flow down causing a lean mixture. The mixture got so lean that that cylinder developed very high temps, causing the top of the piston to melt, the top ring land on the piston gave way allowing the piston ring to cock in the bore. The ring broke apart, the broken parts started bouncing around inside the cylinder causing the damage you found. Could it be that a part of that broken ring is seized between the piston and cylinder wall, keeping you from rotation the assembly?

 

[m16ty]

Lean condition doesn't cause problems in a diesel like it does in a gas engine. If a diesel leans out it just won't fire. The main thing that causes a melted piston in a diesel is leaking injectors dumping too much fuel.

 

[ranchhopper]

Looks like one of those engines they finished up late on a Friday afternoon.

 

[Trailboss]

Some of the piston pieces even made it into the #1 cylinder.

It's amazing how broken pieces travel from one piston to the other. When I dropped a valve in an NHC250, metal parts from the #3 cylinder and piston destroyed the #4 cylinder.

 

[Rifleman]

M16ty, thanks for the info on diesel engines, i know gas engines real well but still have lots to learn about diesel's.

 

[Ferroequinologist]

Ok it is looking like the oil was not making it to #2 piston. Hence the overheating and failed piston. Pics tomorrow in the light.

 

[bigugh20]

Dang Adam, what a mess. Is that the tractor? What a perfect LOOKING truck to be so messed up.

 

[jw4x4]

Dang Adam, what a mess. Is that the tractor? What a perfect LOOKING truck to be so messed up.

This just goes to show that APPEARANCE isn't everything. And I am not just talking trucks. Same goes for humans, too.