Deuce multifuel engine damaged piston burned/ overheated!!

[G-Force]

I was leaning more towards timing due to your lack of power but after reading this article
Heavy Duty Technology: Piston Failure Analysis: Engine Builder
I would look at your piston cooling nozzles for proper installation and aiming. You also said you had damage in #1 cylinder and you believed it was passed over from #3. it could be you were having another failure in that cylinder. You made a statement that both these cylinders are at TDC at the same time. This is not true. When #1 is at TDC #6 is at TDC' This is what is called companion cylinders. In other words the pistons for these two clyinders are in the same location in their respective cylinders at the same time due to the crankshaft. While one is on its compression stroke the other is on exhaust stroke. So it would be 1-6, 5-2, 3-4. what does the pisotn crown on #1 loook like? Judging from the looks of the valves in the heads for #1 and #3 they both were overheating.

 

[EveOfDestructionDeuce]

Sorry for the late reply, i'm in holiday now and with iPhone you write like a snail. I will check the egt, i have a pyrometer in my superbee if these one will be useable for that engine.Before if Start that repaired engine again i will use other injectors, my auto Meter gauges for sure i dont trust the original SW military gauges.I'm also very sceptic with the old injection pump, in will disassemble them again and control them

 

[EveOfDestructionDeuce]

The piston damage will be as follows, piston no 3 was totally meltet at the top, as you see at the pic i saw also that the heat was only at the top, because the rest of the piston under the rings looks good, so the mistake was inside the combustion chamber above the rings so the engine oil tube under the piston must work.What i don't wrote is that the number 1 and 2 cylinder having also damages at the sleeves resulting from the small aluminum pieces from cylinder no3 they are " glued" at the sleeves like cream so the rings and sleeves are death.the top of no1 and2 pistons looking normally and the valves and valve seats from no 1 are also damaged like on 3 and the valves stuck a little i tried with as plastic hammer. with other words all cyl. From these head are damaged, the other cyl.4,5,6 under the other head looking absolutely okay. i don't understand how was it possible that the aluminum particles entry 1,2 cyl.?coming in over the exhaust valves, because no1 valves open when no 3's are closed, so it was pushed in from the exhaust stream/press? I also hope the turbo are okay, that the alum. Pieces haven't shot the blades at 20000 rpm

 

[tm america]

Well, the exhaust manifold is divided, so you can install one thermocouple in each and display the two readings on one gauge (center gauge in image below). This arrangement provides a reference in case one cylinder is misbehaving...

I really like that gauge.. Where did you get it ?What brand is it.. I am looking to do a pyro and new boost gauge in my truck real soon.. any info would be great.Thanks

 

[motomacguyver]

I also hope the turbo are okay, that the alum. Pieces haven't shot the blades at 20000 rpm

If any aluminum got past the exhaust valve, it pretty much has to go through the Turbo. I would definitely check the blades for damage.

 

[motomacguyver]

These are out of engines that were under 2K hours and were both running perfect.

Who knows what causes this-Kenny? M-35 Tom?

Not positive on the piston cracking, but on 4 stroke, 2 valve, air cooled, motorcycle engines; their is a phenomenon known to cause cracking between the intake and exhaust valves. The way Kevin Cameron (cycle world editor) explained it, was that the repeated heating and cooling if the particular area would cause LOCALIZED expansion and contraction. This repeated stress would eventually "pull apart" the material between the valves. Also I would think that any erosion of the piston would accelerate the cracking process due to stress risers. I wonder if that is why the deuce pistons have cracks?

 

[goldwing2000]

i would think a clogged injector which would caue a lean condition which could melt a piston due to detonation

Sure... in a gas engine.

 

[treeguy]

I have the same cracking on my pistons all in the same location. I replaced the head gasket last year in January. Most everyone I talked to said this was common because of the thinness near the swirl edge and that there was plenty of thickness as a whole to the top of the piston. I guess I'll run her untill it looks like the OP's, but for now, a year later she runs great. If it is a lean, hot issue causing the cracking, maybe turning up the fuel a little might help and not lugging the engine. I didn't have the cash for new pistons and sleeves and rings and a kitchen sink, but the hot rod shop I brought the heads to fixed them up. They planed the deck surface and replaced some valves and pressure tested them. Does anyone else have info on the piston cracking?

 

[goldwing2000]

Treeguy: in case you didn't catch it, when a diesel engine runs "lean", it doesn't heat up like a gas engine. Overfueling will cause a diesel to run hot, not underfueling.

Fyi, I work in a dyno lab and we are testing brand new 3.2L diesel engines that are for military use and they have cracks in the pistons, too. Sometimes the cracks will propigate into holes but these engines are running 300HP, 550lb-ft of torque and 4300 rpms. I wouldn't worry about a 1/2" long crack in an LDT piston.
With your clean heads and new valves, your engine should last longer than you do.