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Discussion Starter #1
Seeing as there are some very smart people on this forum..............
We use a converted bus as our race transporter, it "was" powered by a 500ci straight 6(4 stroke) turbo diesel engine.
What would cause a diesel engine to generate enough combustion temperature to melt a piston??????


This engine has covered around 780,000 miles and has something like a 0.030 wear ridge on the bores.The injectors were replaced last year due to two of them having broken or cracked nozzles.
Any ideas welcome.....................

Brain.
 

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I'm no pro but I know when I was running a chipped power stroke my EGTs would climb to 1,600 degrees going down the race track in 150+ mode. If I understand the way a diesel works, if you have too much fuel and not enough air it can drive your egts up.
The turbine side of the turbo probably looks the same way.

Then again I have heard of people melting down a stock diesel engine by staying full throttle under high loads for extended periods of time. (Climbing a long hill with a load under full throttle or just in emergency situations.)

1,200-1,300 is about normal under high load full throttle. Anything above that is when melt down starts. (If I remember correct.)
 

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Discussion Starter #4
richter69 said:
did the cracked injector/s come out of that hole?
I can't remember, to tell the truth, but I suspect the answer is yes.........

At least two of the other pistons look like they may have cracks in them.
One of them has a patch on the quench area that is very rough-looks eroded.

The head is also cracked across an intake valve seat but not on the melted cyl.

Brain.
 

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Too much fuel and not enough air will make a bunch of heat in a diesel.

The cracked tip would have dumped an uncontrollable amount of fuel and the spray pattern would have been off and well as the atomazation.
 

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I agree with Jon. It looks like you had injector issues. Either a bad reman or they were not adjusted correctly (depending on what type of engine/fuel system is used on that engine).
 

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As a kid I sued to see that quite a bit on tractors. Farmers, being barn-certified mechanics, authorized themselves to crank up the pumps for more power.

Brad
 
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