924Board.org

[TajMan]

Car has around 140K miles on it.
Was always running pretty tops previously, until stored then it had a problem diagnosed as bad headgasket.
Car should be running better and cleaner after headgasket job. Some intake air leaks will be fixed, exhaust was just fixed, ignition components were all just refreshed.
Oily deposits on pistons/head point to running rich/engine inhaling some oil, which is what I'd thought..


bad spot on headgasket, blown open in coolant passage around piston water jacket:


after some piston cleanup, careful scraping with razor blade then wiping with acetone-soaked shop towel:

(one piston done, one partially acetone wiped, 2 somewhat scraped..)

head:

see this valve, the most 'burnt':




So, pics before any head cleanup. .
What say you on the one valve that looks like it suffers more than all the others (exhaust valve cyl #4?)?
Compression was down just a bit on cyl #4 vs the others, but all still close enough proximity engine can survive fine without full head rebuild at this time, IMO.
I think I'll clean up head as best I can and get it all back together with new top-end gasket kit.

Should I do anything, like check for valve leakage with brake parts cleaner sprayed down the ports & pooled up? Is it ever good to replace just one valve with a used valve and no other head rebuild work done?
(unfortunately i'm fixing this car to sell, it won't be my baby I'll keep around)
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'87 924 S

[Paul]

Can't be sure from the picture, but that valve may be ok.

If your head gasket set has valve seals, why not pop the valves out, clean and lap them and install the seals?
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

[TajMan]

I had seen this:
http://www.youtube.com/watch?v=5GWBrsGTR2s

Maybe I can fab my own tool to compress valve springs for removal? If I wanted to replace valve stem seals I'd need something to do that.

How would you go about 'lapping' by hand with valves removed? 2,000 grit sandpaper after cleaning?
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'87 924 S

[edredas]

[Paul]

http://www.dsmtuners.com/forums/articles-engine-fuel/341636-how-lap-valve.html


_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

[TajMan]

I'm so glad you linked a thread on DSM tuners, haha!
_________________
'87 924 S