Piston Cracks

[turbodiesel94]

I have a spare turbo motor I picked up from a junkyard that i was going to tear down and rebuild/freshen up. Engine has unknown mileage also. I pulled one of the heads off last night and each piston had a crack in it right at the valve dimples, I thought i read something about this being common on these engines? The cylinders looked in great shape with much of the cross-hatching still visible. Head gasket didn't look damaged at all either. So are these cracks normal or am i looking for a new set of pistons?

 

[86truckpull]

If there cracks I wouldn't leave them buy new ones dps makes ceramic coated pistons 38bucks a pop

 

[hesutton]

Those impression in the pistons are not valve reliefs. If you look closely, they are off center and not alined with the valves themselves. Those are the combustion chambers in each cylinder. The exploding diesel exits the prechambers and enters the cylinders at that point on the pistons. The burning diesel vapor expands into those pockets and completes it's combustion there.

Cracking there is not something I've seen on the IDI's that I've torn down. The most recent (my crew cab) had 322,000 on the clock and the pistons were not cracked and in excellent condition. Cracks should not be there. Cracking could be damage from high EGT's, excess boost (not sure if it was turbo'ed), hydraulic pressure (water/coolant/other liquid), or something else.

Heath

 

[bike-maker]

Common place for cracks is in the pre-chambers; there hard as hell and also brittle, so they crack fairly easily. But there really isn't anywhere else for these cracks to go.
There is no such thing as a crack getting smaller. Don't use them.

 

[trapper]

If there cracks I wouldn't leave them buy new ones dps makes ceramic coated pistons 38bucks a pop

if im not mistaken dps charges 38 bucks each to coat your own pistons

 

[86truckpull]

Now that u sayy that I think your right but summit racing has stock pistons also and there not that expensive dnt cut corners while rebuilding the motor a little money in the motor now will save u a lot of headaches

 

[turbodiesel94]

Damn. yes the engine was turbo and even had an IC. I'm going to take a guess and say high EGT's. Any other places besides DPS that would be good for pistons?

 

[typ4]

falconglobal on ebay.

 

[bbjordan]

Cracked pistons

You mean like this:

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This was a severely used engine. Both exhaust manifolds were cracked. Some of the exhaust valve seals were melted too!

 

[racer30]

I have a Engine out of 94 turbo truck ,, 6 pistons cracked one grenaded and bent the rod three bent push rods and the engine still ran when the guy took out the Engine. He said :ITS GOT A DEAD HOLE AND A KNOCK "..... That was the first Engine I bought. I have learned alot from that. OH it had 132000 miles on a ford rebuild and the turbo ip still had the seal paint on all the bolts for warranty.

 

[icanfixall]

Falconglobal sells a set as does Diesel direct in florida. All stock oem pistons are Mahle. Even the turbo pistons. They offer a low compression piston too. I personally would not run anything els in my engine. They worked really well in plenty of used up engines over the many years of use. Really do not reuse a cracked piston. It may never get worse but surely it will never get better either. Its a bad idea to take a chance like that...BTW did you get the intercooler with the engine and what kind was it...

 

[turbodiesel94]

No I am definitely replacing the pistons now, as long as the bottom end checks out Ok too. I did get the intercooler with the engine and it has a garrett sticker on it, all the piping for it which have ats stickers, and the complete turbo setup including an ATS upgrade and 3'' downpipe. It also has a different compressor housing that is not stock. I paid $900 for all of it about a year ago, might have been a little too much but I wanted that entire setup.

 

[turbodiesel94]

http://cgi.ebay.com/ebaymotors/Ford...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

Would that be the correct kit I'm guessing?

 

[icanfixall]

Yes but... And you knew there was going to be a big butt.... Anything in the supplied picture is not what your buying. Thats just a generic chevy small block pic of parts. Our engines have gear driven cam and the oil pump pictured has a drive shaft on it. Ours is gear driven off the crank so... Don't look at pics thinking thats what your buying. I'm never a buyer is the picture does not fit what I'm buying. Falconglobal is a fine company to buy from after all this information. I don't recall anyone in the past 6 years having any issues with them. The other issue shops are clearly listed in the Hall of Shame....

 

[turbodiesel94]

Yeah I noticed the timing set there in the picture, I was going by the description in the ad. Just wanted to make sure its the one for the larger turbo wrist pins. I also see it comes with a new oil pump, with an engine that has unknown mileage would that be something to stick in? I have heard that the OEM pumps in these pretty much last forever.