Cracked piston

[Norwegian-Blazer]

When my old 6.2 l had a cracks in the engine block i replaced this with an used rebored block, new camshaft and pistons. The engine worked fine for some years when it suddenly got an misfire on one cylinder. Problem was a cracked piston :

http://i117.photobucket.com/albums/o44/ENKB/6-2-1.jpg
http://i117.photobucket.com/albums/o44/ENKB/6-2-2.jpg


Replaced this piston and continued driving but now 2 years later the 6.2 again suffers of an irradic idle.

Removed the oil pan yesterday and this is how things looks from below :

http://i117.photobucket.com/albums/o44/ENKB/6-2-3.jpg

http://i117.photobucket.com/albums/o44/ENKB/6-2-4.jpg

For me it seems like some (all?) of the pistons is breaking up, any suggestions to what causes this ? bad timing ? bad pistons ?

[DmaxMaverick]

It could be timing related, if it's too advanced. Is the engine turbocharged? Does it have an EGT gage? How many miles on the injectors? What brand and grade (OEM, marine, high-pop, etc.) are they? Bad injector(s) can cause increased EGT's. Is this unique to only one cylinder? If so, it could be related to a bad con rod. Any of the above and/or a sloppy con rod could cause piston failure.

If the rest of the engine is still sound and crack free, there's no reason to not repair it and continue. I suggest, under the circumstances, you use ceramic coated pistons, and install an EGT gage, if it doesn't have one, before running again. This doesn't just happen, normally, unless something else is wrong. Having one piston fail is not too uncommon for various reasons, but for it to repeat in a relatively short period is not at all normal.

[Robyn]

I see the piston is stamped .75 It has been bored and aftermarket pistons installed.

Some of the aftermarket pistons have a nasty habit of breaking in the 6.2/6.5

I have seen factory pistons crack the crown, but not the catastrophic cracking that you are seeing.

Mahle brand pistons are great for these engines.

Some of the "white Box" stuff is junk. They may work ok in gassers but dont do well in the diesels.

As Maverick mentioned, timing and other factors can influence things too.

Keep us posted

Robyn

[Norwegian-Blazer]

Not turbocharged engine, installed 8 remanufactured standard injectors in 2005.
Yes bored and oversized pistons installed.

[Robyn]

What brand of pistons were used??

Robyn

[Norwegian-Blazer]

Badger pistons

[Robyn]

I found reference to Hastings being the company that makes Badger.

I am not a fan of most of the aftermarket pistons for the 6.2/6.5 engines
The Mahle (brand) is or has been a stock type factory piston.

The type of failure most commonly seen with the 6.2/6.5 is a heat crack in the recardo bowl due to bad injectors or too much fuel and boost when trying to make max power.

The amount of cracking seen in your piston is just not normally seen in these engines.

I have never seen one broken that badly unless the engine ingested something hard through the intake.


Might want to consider a set of Mahle pistons or look around and find a set of factory .75 OS pistons.


Best of luck

Robyn

[diaric]

the cracks are coming straight up through your pin. its happened twice to the same piston. as was suggested, check your wrist pin bushings. chances are that one is really sloppy and has been hammering the piston. by the top photo, it doesn't look like the piston ate anything. when i did my rebuild, all mine were shot. won't matter what brand of pistons you have if this is the case, it will fatigue them all

[Norwegian-Blazer]

the cracks are coming straight up through your pin. its happened twice to the same piston.

Looks like the "new" piston is ok.

[john8662]

My first thought was Silvolite pistons, as their Diesel pistons were very poor quality and would crack. I cannot see your pictures though...

Two pistons I'd consider as replacements, since you have to tear it down again anyways, are Mahle and Sealed Power (Federal Mogul).

J