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  #11  
Old 12-01-2012, 11:28 AM
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Quote:
Originally Posted by Rossterman View Post
If bores are good, hone and put in new pistons and rings along with rod and main bearings. Parts are pretty cheap for these engines and aren't marine specific.
X2 on that and what CantRepeat said. If you're into the engine that far, I would do the hone/bore and replace bearings, pistons and rings.
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  #12  
Old 12-01-2012, 11:40 AM
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i would get a rebuild kit from jegs or summit with new pistons, rings, bearings, oil pump and blah blah blah it would
be cheap insurance
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  #13  
Old 12-01-2012, 11:42 AM
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Originally Posted by 1redTA View Post
i would get a rebuild kit from jegs or summit with new pistons, rings, bearings, oil pump and blah blah blah it would
be cheap insurance
Yup, you can get some screaming deals buying a master kit.
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  #14  
Old 12-01-2012, 12:14 PM
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A bit of anecdotal experience here. I pulled the head on my BMW M20b25 engine (92 325i cabriolet) b/c it was leaking oil (common problem with an older M20) and I discovered damage to two piston tops similar to the first pic you posted op. My guess was that the engine was running lean and blew apart the insulators on a couple of the spark plugs. The white ceramic bits banged around in there and dimpled the tops of the pistons. I only guess this b/c right after buying the car I replaced the plugs and noted that some were damaged, and I noted which cylinders they came from.

Anyways, cleaned them up, put it back together, and it's been fine. There is about a 10 psi split between highest and lowest cylinder compression. The cylinder walls on those cylinders were damaged by the debris too, but the engine doesn't consume oil and compression is within spec, so I'm running it that way. I've since had the injectors refreshed, which should cure whatever lean issue the engine might have been having.
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Old 12-01-2012, 12:17 PM
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Yeah I got my entire kit minus pistons and oil pump from summit. Guess I can order some pistons too. Are the wrist pins pressed into the rod? That's the only thing I can figure. Any tips on removing them?
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  #16  
Old 12-01-2012, 12:44 PM
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Quote:
Originally Posted by jfw432 View Post
Yeah I got my entire kit minus pistons and oil pump from summit. Guess I can order some pistons too. Are the wrist pins pressed into the rod? That's the only thing I can figure. Any tips on removing them?
Yes they are pressed in.

Take the new pistons and the rods to a machine shop and let them press the new ones on. They will do it a lot faster and you won't have to rig something or beat the pistons up trying to do it by hand.
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  #17  
Old 12-01-2012, 01:55 PM
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I'm sure the machine shop will tell you but, don't forget new cam bearings while you have the motor torn down; freeze plugs too(brass).
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  #18  
Old 12-01-2012, 01:56 PM
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Quote:
Originally Posted by jfw432 View Post
Yeah I got my entire kit minus pistons and oil pump from summit. Guess I can order some pistons too. Are the wrist pins pressed into the rod? That's the only thing I can figure. Any tips on removing them?
They are pressed in and most machine shops heat the end of the rod a little before pushing the pins back into the new pistons.
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  #19  
Old 12-01-2012, 02:49 PM
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Quote:
Originally Posted by CantRepeat View Post
I'm sure the machine shop will tell you but, don't forget new cam bearings while you have the motor torn down; freeze plugs too(brass).
Got 'em but thanks for the reminder. Had to buy a used cam bearing tool though because I didn't have anything like that in my arsenal of tools.
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  #20  
Old 12-01-2012, 11:35 PM
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Check cylinder wall taper. If 12 thousands or greater bore it the ring mfg will not stand behind rings to seat in.
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