Author Topic: what happened to my piston?  (Read 2106 times)

Offline mrnda

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what happened to my piston?
« 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.
« Last Edit: March 03, 2012, 01:15:45 PM by mrnda »

Offline Jason S

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Re: what happened to my piston?
« Reply #1 on: March 03, 2012, 02:15:58 PM »
It kinda looks reminiscent of the piston ring gap set too tight. 
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Offline jaredts

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Re: what happened to my piston?
« Reply #2 on: March 03, 2012, 02:41:51 PM »
I won't pretend to know, but detonation can cause all kinds of damage.

Offline chuck13

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Re: what happened to my piston?
« Reply #3 on: March 03, 2012, 05:47:59 PM »
Yep,looks like detonation to me too.Only on the #1 cylinder?

Offline VileZambonie

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Re: what happened to my piston?
« Reply #4 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.
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Offline mrnda

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Re: what happened to my piston?
« Reply #5 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.

Offline Blazin

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Re: what happened to my piston?
« Reply #6 on: March 04, 2012, 10:37:40 PM »
Pic of the bottom of the head for those two cylinders = combustion chamber.
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Offline mrnda

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Re: what happened to my piston?
« Reply #7 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.   

Offline jaredts

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Re: what happened to my piston?
« Reply #8 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?

Offline VileZambonie

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Re: what happened to my piston?
« Reply #9 on: March 05, 2012, 07:58:10 PM »
So you put it back together like that? Why did you pull it apart?
,                           ___ 
                         /  _ _ _\_
              ⌠ŻŻŻŻŻ'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline mrnda

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Re: what happened to my piston?
« Reply #10 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.