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Redline Racer
Join Date: Jan 2007
Posts: 2,444
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Possible to replace valve stem seals without removing head?
The thing's been using oil alot lately and doesn't leak to any noteworthy degree. When I re-did the balance shaft housings, it stopped sucking oil into the intake, so I'm thinking the rings are in decent shape (originally thought blowby could have been a major culprit). It compression tested pretty well a few months ago (~150-160) which leads me to believe the only other way it could be burning oil is through the valve stem seals, or is it possible to have worn out just the oil scraper rings and still have decent compression?
Anyway, I want to start with the cheap and easy first. I know I've heard you can pressurise the cyl with air, which holds the valves closed in order to release the spring and get to the seals, but does it work on a 944 motor? Here's compressing the spring from the top on a 928 head. 
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1987 silver 924S made it to 225k mi! Sent to the big garage in the sky |
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06-08-2009, 08:44 AM
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your average wrencher...
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yes, it will work on that engine. a 16 valve would be a little more trickier.
first, tap loose the retainer with a hammer just to break it loose. then use the air and that tool above (OR something like it) to get the retainer off. just don't drop the keepers!
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1982 931 *project* 1986 951 Garrett turbo, Rogue Tuned (sold  )1987 944S chipped, konis, rollbar (traded) 1979 924 total rebuild and blueprinted (sold) |
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06-08-2009, 09:36 AM
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Registered
Join Date: Nov 2007
Location: Chesapeake, VA
Posts: 66
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The "low tech" way is to take some cotton rope and feed it into the spark plug whole until the combustion is full. This will keep the valve from dropping. It's obviously easier if the piston is at the top of its stroke.
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1970 Porsche 914 1.7 1987 Porsche 944 2.5 NA |
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06-08-2009, 10:12 AM
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Registered
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put some rags in the oil return holes so you don't drop anything in there.
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Tom 1990 944S2 Cabriolet 2002 Chevy Silverado 2500HD 2003 Maroon Ford F350 dually |
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06-08-2009, 02:59 PM
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Registered
Join Date: Feb 2004
Location: north wales Pa.
Posts: 485
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Use a compression tester hose, thread the end into the spark plug boar and add an air hose fitting nipple to the other end. Connect to an external air compressor. This will keep the piston susspended in the valve boar. release the spring and retainer. We do it all of the time when replacing them here on any of the 4 or 6 valve engine we service.
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autowerks9 PCA SINCE 1991, REISENTOTER 1982 EURO 928S 320HP MEDIORMETALIC/BURG. 1987 944S- GT3 BODY CONVErSION RED/BLACK( sold ) 2003 MERCEDES E500 Sport "Einfarbig" |
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06-08-2009, 03:21 PM
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1986 Porsche 944 turbo
