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Walt Fricke Walt Fricke is offline
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Join Date: May 2004
Location: Boulder, Colorado
Posts: 6,555
1) A stuck relief valve, because it is vertical, can be removed by pulling the idiot light sender on top of the engine (where the picture shows a mechanical pressure gauge), and using a suitable rod to persuade the piston to come out the bottom. This won't work for the safety valve, however, as the horizontal passage doesn't come out the other side of the case assembly. Don't recall if there is access to from the inside if the case is apart, but at worst one could apply air pressure in that instance.

2) It doesn't surprise me that Porsche gives one pressure for one model of motor, and another for another. Also note that the 3.2 oil pressure specs I got (from Bentley, if I recall) are higher. Don't know just what that might mean, other than they kept changing their engineering minds about how much pressure was needed. Lower pressure may equal better gas mileage, but not allow as high a redline RPM. The 3.2s have a lower rev limit than the 3.0s.

3) Here are some part numbers for the GT3 (and I assume, turbo) motors, from a PET parts catalog for the 99-05 996 GT3 (as of Aug 06):

Relief:
Spring 996 107 127 80
Piston 911 107 512 00
Spacer ring 996 107 532 81
Plug 996 107 105 80

Safety:
Spring 901 107 531 00
Piston 911 107 512 00
Plug 999 064 026 02

-So the safety spring is the same as it always has been.
-The pistons are the same as introduced in the later 2.7s, with a groove instead of the earlier hole. I was surprised to learn, from this discussion, that the earliest upgraded systems used the new piston, but not the new, longer, relief spring. One hears that keeping the old spring will lead to oil pressure which is too high, but I've not tested that. Maybe that was why Porsche had to change by '78?
-The GT3 relief spring is a part number unfamiliar to me, and I can find no information as to its length (maybe the longer spring referenced in earlier posts?). I'm going to order one. Perhaps that would be the key to my oil pressure problems with my GT3 pump in an earlier case.
-I didn't bother with the numbers for the hollow tube part for the relief spring, but think it has had the same part number all along.
-I don't know why the relief plug has a 996 part number. I guess I should buy one of those to see how, if at all, it differs. Previously, I believe both plugs (safety and relief) were the same.

Last edited by 304065; 10-25-2012 at 11:57 AM.. Reason: corrected a part number
Old 10-25-2012, 11:05 AM
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