Just bought a white S4 (project)
01-23-2012, 07:20 PM
#31
Rennlist Member
Thread Starter
Damaged bore?
The bore of the cylinder that had the stuck piston had a ring of corrosion. I did some light sanding with 400 grit and some WD40 and cleaned it up a bit.
Before
and After
Still pretty ugly, but fairly smooth. Since it's near the bottom of the stroke, I'm wondering what would happen if it were assembled and run like this. To be clear, this is not the engine I plan on putting in the car, it's the block that came out of it.
Found the injectors. The receipt said new, but they look to be rebuilt. Also got a complete set of injector O-rings with the car if these are too small.
Before
and After
Still pretty ugly, but fairly smooth. Since it's near the bottom of the stroke, I'm wondering what would happen if it were assembled and run like this. To be clear, this is not the engine I plan on putting in the car, it's the block that came out of it.
Found the injectors. The receipt said new, but they look to be rebuilt. Also got a complete set of injector O-rings with the car if these are too small.
01-23-2012, 09:16 PM
#32
Team Owner
if you ran that cylinder it would first damage the rings then the piston would seize
01-23-2012, 11:03 PM
#34
Rennlist Member
Thread Starter
You're probably right, just wasn't sure what the chain of events or failure points would be. Any options you know for repair? What about honing then nicasil coating? Putting a sleave in doesn't seem like a common approach on these engines.
Next step may be to disassemble the TBF engine and see if there's any combination of parts that might have potential between the two engines.
01-23-2012, 11:03 PM
#35
The block may only be good for oversize bore projects. Which are fun. But time and $$ consuming
01-24-2012, 02:14 AM
#36
Nordschleife Master
Stan,
You're probably right, just wasn't sure what the chain of events or failure points would be. Any options you know for repair? What about honing then nicasil coating? Putting a sleave in doesn't seem like a common approach on these engines.
Next step may be to disassemble the TBF engine and see if there's any combination of parts that might have potential between the two engines.
You're probably right, just wasn't sure what the chain of events or failure points would be. Any options you know for repair? What about honing then nicasil coating? Putting a sleave in doesn't seem like a common approach on these engines.
Next step may be to disassemble the TBF engine and see if there's any combination of parts that might have potential between the two engines.
Then ask for their experienced opinion - it may be that a correct "polish" would do it, or otherwise bore that cylinder to a larger tolerance group, or first oversize. (Porsche oversize pistons are the same weight as regular ones - so you can oversize just one cylinder and piston. There's a note about it either in the WSM or the Tech Spec books).
Nicasil would be an $$$ process - you're talking custom pistons, matching rings at the miminum, plus the cost of block prep. If you go that route, you may as well build a stroker or low-compression boosted motor
01-24-2012, 10:04 AM
#37
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Join Date: Apr 2010
Location: Magnolia TX, just north of Houston, Red 1984 S
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Don, I would recommend all 3 cylinders that had the stuck pistons be inspected by someone who knows the Alusil process well. While the other 2 were not quite so "stuck" there were certainly changes in the cylinder wall properties of both where the rings had rusted.
I am using Nikasil cylinder coatings in another engine... LN Engineering seems to be the experts in that technology, as well as some others. They seem to specialize in aircooled Porsche stuff, but they could well be worth talking to. I have found them to be helpful, open, and very honest in my dealings with them. They quote a $235 per cyl price to refurbish and recoat with Nikasil for aircooled engines. YMMV.
I am using Nikasil cylinder coatings in another engine... LN Engineering seems to be the experts in that technology, as well as some others. They seem to specialize in aircooled Porsche stuff, but they could well be worth talking to. I have found them to be helpful, open, and very honest in my dealings with them. They quote a $235 per cyl price to refurbish and recoat with Nikasil for aircooled engines. YMMV.
02-05-2012, 05:00 PM
#39
Rennlist Member
Thread Starter
I started digging into the 89 replacement engine from 928 International this weekend and it's looking pretty good, other than the CPS missing.
The WP looks brand new. The TB is a Conti with the correct tension and also looks new, with no signs of any wear, even the on backside. The back side of the Gates TB on my red car has rub marks on it after just 2k miles, so not sure why this one is so perfect. Maybe the car was totalled right after the TB/WP service.
I'm not big on Conti belts, but I'm definately thinking about leaving this as is. The belt has a weird cloth-like texture on the teeth that I haven't seen before on Gates or Conti belts, and you can see the internal strands on the side of the belt.
The cam gears look great with no signs of wear, so they must have been replaced with the belt and WP since this engine has 93k miles, that would be about right. Nice to get $800 worth of gears on a $2250 engine.
To me this looks like professional mechanic's work rather than DIY because there was very little cleaning done on the tensioner or front of engine. I could see a mechanic doing just the replacements needed and not spending much time cleaning, whereas most of us would have done more cleaning while the covers were off. It seems like at least the tensioner should be cleaner if it was rebuilt.
Can anyone identify this WP? It's got a 928 part number cast into it, but no brand names that I can find. Smooth casting and bright gold pully. Could it be a new Porsche pump?
The WP looks brand new. The TB is a Conti with the correct tension and also looks new, with no signs of any wear, even the on backside. The back side of the Gates TB on my red car has rub marks on it after just 2k miles, so not sure why this one is so perfect. Maybe the car was totalled right after the TB/WP service.
I'm not big on Conti belts, but I'm definately thinking about leaving this as is. The belt has a weird cloth-like texture on the teeth that I haven't seen before on Gates or Conti belts, and you can see the internal strands on the side of the belt.
The cam gears look great with no signs of wear, so they must have been replaced with the belt and WP since this engine has 93k miles, that would be about right. Nice to get $800 worth of gears on a $2250 engine.
To me this looks like professional mechanic's work rather than DIY because there was very little cleaning done on the tensioner or front of engine. I could see a mechanic doing just the replacements needed and not spending much time cleaning, whereas most of us would have done more cleaning while the covers were off. It seems like at least the tensioner should be cleaner if it was rebuilt.
Can anyone identify this WP? It's got a 928 part number cast into it, but no brand names that I can find. Smooth casting and bright gold pully. Could it be a new Porsche pump?
01-26-2013, 12:26 AM
#40
Rennlist Member
Thread Starter
Off to new home...
Just to update and close out this thread, the engine mentioned above, in my last post from Feb-2012, turned out to have quite a bit of corrosion and pitting behind the water pump so it went back to 928 International.
There haven't been many good used engines on the market since that post, and I've been busy doing a complete top end refresh with TB/WP on my 86.5. I've decided I don't want to devote the time to another engine replacement project right now, and it's time to let the car go to someone else. Today it made the journey north to DFW and gets to park next to Herman's red GTS.
I think he needs to give it to Barbara when he get's it going!
There haven't been many good used engines on the market since that post, and I've been busy doing a complete top end refresh with TB/WP on my 86.5. I've decided I don't want to devote the time to another engine replacement project right now, and it's time to let the car go to someone else. Today it made the journey north to DFW and gets to park next to Herman's red GTS.
I think he needs to give it to Barbara when he get's it going!
01-26-2013, 07:52 AM
#42
Rennlist Member
You never know
Just to update and close out this thread, the engine mentioned above, in my last post from Feb-2012, turned out to have quite a bit of corrosion and pitting behind the water pump so it went back to 928 International.
There haven't been many good used engines on the market since that post, and I've been busy doing a complete top end refresh with TB/WP on my 86.5. I've decided I don't want to devote the time to another engine replacement project right now, and it's time to let the car go to someone else. Today it made the journey north to DFW and gets to park next to Herman's red GTS.
I think he needs to give it to Barbara when he get's it going!
There haven't been many good used engines on the market since that post, and I've been busy doing a complete top end refresh with TB/WP on my 86.5. I've decided I don't want to devote the time to another engine replacement project right now, and it's time to let the car go to someone else. Today it made the journey north to DFW and gets to park next to Herman's red GTS.
I think he needs to give it to Barbara when he get's it going!
I now realize its was a complete set up by...?
01-26-2013, 11:06 AM
#43
Rennlist Member
Thread Starter
01-27-2013, 03:42 PM
#44
Rennlist Member
Sharks are hitting my line brought home two 928 in 24hrs
Last edited by Herman K; 01-27-2013 at 03:58 PM. Reason: Start as a new thread
01-27-2013, 07:49 PM
#45
Team Owner
Looks like a lotta fun
Last edited by Mrmerlin; 01-27-2013 at 09:58 PM.
