speedo

iTrader: (15)

This is out of a guys 01 M6 WS6 with 68K on it. He has owned the car under a year so we don't know all the history on it but it came with just headers, catback exhaust and a 4.10 gear . He started getting #5 missfires last summer and it continued to get worse over a short amount of time with shooting the blues and such. Finally got it tore down this spring.

Shot some pics of the#5 pistion....what could of caused this damage? All the other pistions look like normal wear...




Couple more shots....

http://i27.photobucket.com/albums/c1...b/IMG_0935.jpg
http://i27.photobucket.com/albums/c1...b/IMG_0936.jpg
http://i27.photobucket.com/albums/c1...b/IMG_0934.jpg

Grimes

iTrader: (3)

perhaps the previous owner was running a 100 shot? ?

black01_WS6

iTrader: (13)

could be from nitrous, but it usually takes out #7 not #5. how did the rest of them look like?

speedo

iTrader: (15)

Buddy thinks the same thing.....being on the bottle but everything else looks to clean. I forgot to add the cylinder looked really good also. Slight hone job is all it needed.

I think there would have been more damage to the top of the pistion due to detonation on the bottle and it would of took out a few more in the same area....

GuitsBoy

iTrader: (4)

Whats weird is that there dosnt seem to be much pitting on the top of the pistons from running lean, but im not sure how else he could have broken those ringlands. Id put money on it that the car was running some sort of power adder though.

indyboom

iTrader: (11)

I third or fourth that.. Maybe they only rana few passes, That break sure is clean too..

PREDATOR-Z

Looks like mine, and it took out both #7 and # 5 (nitrous)

skipperbisket

iTrader: (4)

i took out #s 5&7 also, i did mine NA and stock internals though...not really sure how it happened but i would guess a major lean condition and some wicked over reving.

cantdrv65

iTrader: (3)

Yeppers...perfect example of what detonation can do, especially when on the bottle. It does/can happen N/A also, but much more often on the bottle. Many people do not keep close tabs on A/F when they spray, or even bother to tune properly....

lowchevy2go

iTrader: (4)

was your car knocking?? how did you know it did that ..waht were the signs

cantdrv65

iTrader: (3)

It will miss like a bitch and have alot of blowby with just a cracked ringland. Eventually they end up like this and depending on where the pieces go the noise could get fairly loud.

eallanboggs

iTrader: (1)

I'd like to know where those chunks of metal went since they're not missing from pin end side of the piston where there is a relief. It's hard to believe the cylinder walls were not damaged.

VORTECFCAR

iTrader: (2)

My '91 had two pistons that looked very similar after I overrevved it on a 150 shot...

the car was driveable but had serious blowby

Im guessing the missing chunks of metal were being held to the piston by the rings? if this were the case, there would be no scoring of the cylinder walls.

good luck, Nick

Fireball

iTrader: (21)

when my #7 failed that is what happened, pieces were held in place by the rings.

slowpoke96z28

iTrader: (2)

what did the plug look like? was the porcelain peppered with piston pieces? i cant see the picture here at work(****** firewall), but it sounds like you guys are talking about broken ring lands or a holed piston. if the nitrous didn't do it, i'd look at the injector for that cylinder.

BES Stroked Nova

iTrader: (24)

my buddies 01 ws6 has the same thing on #5..... no power adder.

ohh well **** happens

ramairws6

iTrader: (33)

I worked on this car and did a leakdown test for compression. The guy bought it like this and had no idea there was anything wrong with the engine. It idled a little rough, but once you got the rpm's up, you didn't notice too much difference. Also,the check engine light didn't come on for miles of driving so the guy that sold it cleared the codes and sent it on it's way! There are some true shady people out there that pray on others that have no clue about whats going on. When I pulled the plug to do the compression check it was looking like new. I smelled a rat instantly! Oh well......live and learn the expensive way?! I'm almost sure nitrous was used on this car.Lots of switches and wire going nowhere hanging under the dash and in the console. Traver

BLKWS.6

Where I used to live (McAllen, TX) selling a car like that to certain people was like handing them a loaded gun and cussing their mother