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So, I found this on an engine I am looking to reseal and have the heads done.
Looking for advice or opinions on what the downside is to putting this back together as is.
Or other input.
So, The cylinder definitely ate something. Pits and dings on the bottom side of number four piston with Gouges on the piston wall. The gouges are the black marks. Was unable to get reliable leak down test. Aside from the dings on the piston, it looks no different from the others with carbon buildup.
The dings and gouges are in mostly harmless places that could be easily fixed by decking the block, even if you don't the fire ring should take care of it.
The scratches aren't unusual but if you can easily catch your finger nail in it you should either machine that cylinder to the next size piston or get a new block.
Personally I would look for another shortblock. Talk to Mark..
I say shortblock because then you know bore and deck condition. Worth checking bottom end and crank endfloat on any replacement candidate too but I am sure Mark can help with that...
Well, I can’t really complain it’s been a daily driver for eight years and The thrust bearing damage was done well before I took ownership. So the fact that I can still drive it every day is a testament to how robust the engines are. I am a bit frustrated now because I had a full head of steam to begin the build process. It will all work out just a little bumpy along the way. I will tell you, that if it wasn’t for the great support of this forum and all of the vendors I wouldn’t even consider any of what I’ve done so far. I really do feel pretty accomplished in what I’ve had to do so far.
at this point I am debating on starting on the black 89. I really wanted to get the red car back on the road. I guess right now I am in a holding pattern until I hear what options I have from the seller.
Getting a "perfect" core engine, ready to install rings and bearings is getting to be extremely rare....after all, they are all 25+ years old, now.
It's my opinion that selling/buying a "good" engine is foolish, these days. I'd be selling "unopened" used engines as "rebuildable cores"....only. That's what I always hope to get....something I can rebuild.
Fortunately, Porsche still has 1st oversize pistons (100.5mm) available for the S4 engines (the only pistons they have for '85 and later engines)....and they are not "mega" bucks.
I keep a set in stock, at all times, so I don't have to wait for pistons to come from Germany, when someone needs a set.
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
02-28-2019, 01:54 AM
Piston and cylinder damage
