Piston crack.... How this happen?

[norkahinz]

This is wierd, I was traveling in the highway at 75 mph and out of the blue a big pop sound is heard. After checking everything I found I only had 2 piston working. so my first guess is the valve are gone. Well the head is a full build SDA head, port polish oversize valves, cams and everything in it is SDA. THEY MAKE GOOD STUFF, nothing happen to the head at all. It is in perfect condition. However; piston 4 is crack and 1. Big hole on the top side. (I will post pic when I get home tonight) How will this happen? not even the shop I take the car to can't tell me why this happen. They said most of the time valve goes out first.

Piston are hypernoumetic (how ever it is spell) .30 over

so now I'm on the hunt for a new set of .30 with matching rings.

[punkboySL2]

Some people have had bad luck with the aftemarket hyper pistons. Adam had one crack on him after about 10 or 20k on it and his build was done right and the car was running properly when it went. I had like 50k on mine with no issues so it seems like some of the pistons weren't manufactured too good.

[leighv]

Whats all that crap on top of the piston? it doesn't look like regular carbon buildup...

[Chris25]

Had the same thing happen to my number 4 piston and they were stock. Had a ton of carbon build up on it like it was burning oil probly got a hot spot.

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[Chris25]

That's how mine looked

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[norkahinz]

No oil burning. So got no idea why so black in top of the piston. I will order a new set and go from there. Any sugestion?

[S.Bretz]

If the egr is blocked, that will cause that. You can get away with no egr if you have a way to tune the fuel and timing to prevent high chamber temps.

could be the clearances where off too.

[norkahinz]

I have Egr working good no blockages. about tuning I must say it is a little off. all I have is a SAFC for an all motor. I might have to some day go with MS.

[S.Bretz]

YOu have fuel pulled out at low throttle?

[norkahinz]

bretz sorry I don't get it what you are trying to say? When engine is regulating from time to time it will have strong fuel smell

[S.Bretz]

If you pulled out fuel with the safc under cruising conditions, then its possible that the engine leaned out and cooked the tops of the pistons off (weakened the top to cause top ring land failure). Usually the PCM wil untune your safc settings at low throttle, but if you go to far the PCM cannot correct enough.

[Kob]

Some people have had bad luck with the aftemarket hyper pistons. Adam had one crack on him after about 10 or 20k on it and his build was done right and the car was running properly when it went. I had like 50k on mine with no issues so it seems like some of the pistons weren't manufactured too good.

Here was my piston after 9,000 miles lol.

[Donnie]

Here was my piston after 9,000 miles lol.

17k+ on my .040 over SPs, and that engine is still strong like bull last time I started it.

Yeah, they definitely put out a few flawed batches.

[S.Bretz]

Judging by the skirt, the piston looked like it was run a tad loose.

A loose wrist pin to rod clearance can cause that too.

[Jamie Q.]

geez always after reading what bretz types, i feel like is saying it from an alter with an open book in one hand, a silver scepter in the other, and an aztec crown on his head......