Notices
928 Forum
Sponsored by:
Sponsored by: 928 Specialists

Piston and cylinder damage

 
Old 02-28-2019, 01:54 AM
  #1  
firemn131
Addict
Rennlist Member
Thread Starter
 
firemn131's Avatar
 
Join Date: Nov 2010
Location: Southern Maryland
Posts: 769
Default Piston and cylinder damage

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.

Thanks







firemn131 is offline  
Old 02-28-2019, 02:13 AM
  #2  
The Forgotten On
Addict
Rennlist Member
 
Join Date: May 2012
Location: Thousand Oaks California
Posts: 3,292
Default

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.

You definitely need a new piston though.
The Forgotten On is offline  
Old 02-28-2019, 05:44 AM
  #3  
C531XHO
User
 
Join Date: Jul 2015
Location: Edinburgh
Posts: 303
Default

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...

Last edited by C531XHO; 02-28-2019 at 06:37 AM.
C531XHO is offline  
Old 02-28-2019, 07:52 AM
  #4  
SwayBar
Addict
Rennlist Member
 
SwayBar's Avatar
 
Join Date: Feb 2006
Location: Chicago Bears
Posts: 2,377
Default

Agree, get another short block.

Checking with a boroscope would have shown this damage prior to buying it.
SwayBar is offline  
Old 02-28-2019, 08:34 AM
  #5  
C531XHO
User
 
Join Date: Jul 2015
Location: Edinburgh
Posts: 303
Default

But I now like to see the deck area as well having bought a car with eroded deck previously...
C531XHO is offline  
Old 02-28-2019, 09:55 AM
  #6  
firemn131
Addict
Rennlist Member
Thread Starter
 
firemn131's Avatar
 
Join Date: Nov 2010
Location: Southern Maryland
Posts: 769
Default

I did not notice this until after it was cleaned up. I have doubts that it would have been seen with a borescope.

Possibly, but I am looking forward at this point.

Appreciate the input.
firemn131 is offline  
Old 02-28-2019, 11:36 AM
  #7  
Speedtoys
Addict
Rennlist Member
 
Speedtoys's Avatar
 
Join Date: Sep 2010
Location: Boulder Creek, CA
Posts: 9,910
Default

That would be easily visible with a good average scope.
Speedtoys is offline  
Old 02-28-2019, 12:48 PM
  #8  
firemn131
Addict
Rennlist Member
Thread Starter
 
firemn131's Avatar
 
Join Date: Nov 2010
Location: Southern Maryland
Posts: 769
Default

One of the pix is the cylinder prior to cleaning. The wall scratches are visible, but not the piston dings.
firemn131 is offline  
Old 02-28-2019, 03:51 PM
  #9  
firemn131
Addict
Rennlist Member
Thread Starter
 
firemn131's Avatar
 
Join Date: Nov 2010
Location: Southern Maryland
Posts: 769
Default

Well, unfortunately my machinist concurs. Need a new block or sleeved. That was not the answer I was hoping for.

Last edited by firemn131; 02-28-2019 at 04:29 PM.
firemn131 is offline  
Old 02-28-2019, 03:57 PM
  #10  
soontobered84
Addict
Rennlist Member
 
soontobered84's Avatar
 
Join Date: Mar 2002
Location: Texas
Posts: 5,001
Default

Originally Posted by firemn131 View Post
Well, unfortunately my machine is concurs. Need a new block or sleeved. That was not the answer I was hoping for.
Is this the extra engine you had? Or is it the engine from the black car?
soontobered84 is online now  
Old 02-28-2019, 04:20 PM
  #11  
Kevin in Atlanta
Addict
Rennlist Member
 
Join Date: May 2002
Location: Roswell, GA
Posts: 5,149
Default

What year engine are you looking for?
Kevin in Atlanta is offline  
Old 02-28-2019, 04:31 PM
  #12  
firemn131
Addict
Rennlist Member
Thread Starter
 
firemn131's Avatar
 
Join Date: Nov 2010
Location: Southern Maryland
Posts: 769
Default

This is my extra engine for my 87.
firemn131 is offline  
Old 02-28-2019, 05:52 PM
  #13  
soontobered84
Addict
Rennlist Member
 
soontobered84's Avatar
 
Join Date: Mar 2002
Location: Texas
Posts: 5,001
Default

Originally Posted by firemn131 View Post
This is my extra engine for my 87.
Well good, I guess(?) Sorry to hear though.
That 87 is fighting you tooth and nail throughout the duration, isn't it?
soontobered84 is online now  
Old 02-28-2019, 06:30 PM
  #14  
firemn131
Addict
Rennlist Member
Thread Starter
 
firemn131's Avatar
 
Join Date: Nov 2010
Location: Southern Maryland
Posts: 769
Default

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.

God is good, it will all work out.
firemn131 is offline  
Old 02-28-2019, 06:32 PM
  #15  
GregBBRD

Rennlist
Basic Site Sponsor

 
GregBBRD's Avatar
 
Join Date: Feb 2005
Location: Anaheim
Posts: 9,791
Default

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.

Bore that thing and deck the block.

Brand new.
__________________
greg brown




714 879 9072
[email protected]

If the kids keep breaking a crowbar in the sandbox, sometimes it is easier to just give them a stronger crowbar, instead of trying to figure out what they are doing in the sandbox.
GregBBRD is offline  

Thread Tools
Search this Thread

Contact Us - About Us - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: