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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: mrnda on March 03, 2012, 01:14:03 PM

Title: what happened to my piston?
Post by: mrnda on March 03, 2012, 01:14:03 PM

removed the head from my engine today (1984 - 292) and noticed some damage to the #1 piston, i have only rebuilt a couple of engines before and have not run across something like this before, what might it be?

Thanks for info and ever coveted knowledge.

Title: Re: what happened to my piston?
Post by: Jason S on March 03, 2012, 02:15:58 PM

It kinda looks reminiscent of the piston ring gap set too tight. 

Title: Re: what happened to my piston?
Post by: jaredts on March 03, 2012, 02:41:51 PM

I won't pretend to know, but detonation can cause all kinds of damage.

Title: Re: what happened to my piston?
Post by: chuck13 on March 03, 2012, 05:47:59 PM

Yep,looks like detonation to me too.Only on the #1 cylinder?

Title: Re: what happened to my piston?
Post by: VileZambonie on March 03, 2012, 07:28:02 PM

Let's see a picture of the relative combustion chamber as well please but I will agree it looks like the result of detonation from the pix you've shared.

Title: Re: what happened to my piston?
Post by: mrnda on March 03, 2012, 10:10:25 PM

chuck:
it was present in the 1 and 2 cylinder, but he 2 is to a much lesser degree.

Zambonie:
I will post some pics of the rest of the cylinder tomorrow but there does not seem to be any scaring or pitting on the cylinder walls, but again i am not the most experienced. 

All:
I will do some detonation research as i am unfamiliar with it, thanks everyone.

Title: Re: what happened to my piston?
Post by: Blazin on March 04, 2012, 10:37:40 PM

Pic of the bottom of the head for those two cylinders = combustion chamber.

Title: Re: what happened to my piston?
Post by: mrnda on March 05, 2012, 09:22:07 AM

Sorry true believers, i did not understand what the combustion section.  The head is already back on, i am planning a rebuild at the beginning of the summer.  Just bought the truck and am anxious to get a couple of miles on it.

There were no abnormalities under the head, all surfaces and valves all looked uniformly colored with no damage.   

Title: Re: what happened to my piston?
Post by: jaredts on March 05, 2012, 09:27:57 AM

What kind of carbon buildup did you have, either in the problem cylinders or as a whole?

Title: Re: what happened to my piston?
Post by: VileZambonie on March 05, 2012, 07:58:10 PM

So you put it back together like that? Why did you pull it apart?

Title: Re: what happened to my piston?
Post by: mrnda on March 07, 2012, 03:59:13 PM

put it back together because i want to get it running.  I will be tearing it down down in a couple of months.  It is only for fun with the kids, a beat me up truck i bought for 600.