Piston damage, how bad is it?

[dnalbach]

I got the rear head off today after fighting with the exhaust manifold for awhile. The head gasket wasn't too bad, there were no missing pieces, only a hole that had corroded out and caused the metal ring to tear inward slightly. The #2 piston appears to have taken some minor damage from hitting the gasket ring where it had torn inward.

How serious is this? I've blown up the picture a lot, it's really fairly small, but it is noticeable.



I'm not equipped to replace the pistons, motor is still in the car and I've been working on it in an apartment complex. Is this piston going to last long term? So far there appears to be no damage to the cylinder wall.

This is my first time inside an engine, so I really don't know how serious this is.

[torq455]

if it were mine, time to get new pistons. if it's a car you dont' really car much about, hell, put it back together. it should run for awhile if you JUST drive it. (grandma)

[1988GTU]

It could last a week, it could last over 50k.... I'd slap it together and save for a newer/better engine.

[dnalbach]

Alright, then my next question is this, if I do put it back together would it be a waste to put the new heads and intakes I just got on it?

And as a side note I'm doing all the work with the engine still in the car in an apartment complex. No garage for me.

[1988GTU]

What is wrong with the old stuff? If the old heads are junk, then you have no choice. If they are good, you still need to have them checked and surfaced. It's your call.

[sil]

i know what its like workin on stuff livin in an apt.. sucks

what kinda new stuff do you have (heads intake ect..) ?
id go with putting it back together buck-choy like and drivin it easy.
try to get a 3400 block and 3500 heads, with lim/uim.
get the custom fitings for the fuel rail, and run your own frp, or get the adapter that rotates the fpr 20* to clear the neck of the manifold.

i wish i would have known about the 3500 stuff becuase i built up my 2.8/3100

[Doubt_Incarnate]

it doesnt seem to have affected the cylinder wall, i'd say your good to keep them in there. i'd go ahead with new gaskets and head bolts just to be sure you dont have any vacuum leaks this winter, unless you like working on a car in the freezing cold with blue knuckles.

[sil]

forgot to mention...
the pieces off the piston must have whent somewhere...
out the exhaust
you should check the exhaust valve for bends... you can do a simple check by putting the head upside down and prop it level, so that you can pour some gas or sommin in the cumbustion chamber and see if it leaks into the exhaust port
if it leaks quickly.. i dunno within the hour than chances are that the valve is bent or chipped/scarred on the sealing surface, and you might get away with a cheap self lap if the valve isnt bent

[dnalbach]

thanks sil, hadn't thought about what happened to the pieces, I'll try that

[Superdave]

what engine is this?

i have 5 extra 3400 pistons in good shape with good rods sitting in a bucket... I'd give you a real good deal on one

All you'll have to do is drop the oil pan, loosen the 2 nuts on the rod cap, slide the old one out, hone the cyl and drop the new one in, swap over the bearings and torque it down... you'll need a piston ring compressor as well... the hone and ring compressor can be rented from Autozone usually.. for free.

[dnalbach]

3100 engine, thanks though Superdave. Sounds deceptively easy, you definitely know your way around a block.

I'm not sure where to buy replacement pistons, or what all else should be done if I decided to take it that far to know whether I can afford it.

[torq455]

not to mention removing the crankshaft. i've never heard of someone being able to install a piston from the bottom due to getting the rings to compress to get into the bore.

[sil]

lol, if your crafty you can use your fingers to compress the rings 1 ring at a time

[CNCguy]

Silly guys... the head is already off so you put it in from the top. :P

[sil]

true.. lol but you still need to undo the rod bolts
then if your under there no need for a ridge reamer to get the crusties off the top of th cyl wall