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Re: Oil pressure light on only at idle Posted by Larry West [Email] (#1140) [Profile/Gallery] (more from Larry West) on Mon, 3 Aug 2009 13:12:57 In Reply to: Oil pressure light on only at idle, Rob [Profile/Gallery] , Mon, 3 Aug 2009 09:44:48 Members do not see ads below this line. - Help Keep This Site Online - Signup |
The stock OP switch is set to an extremely low value, under 10 PSI, usually. Most of the time a Saab motor will run 25+ at idle.
Have you done any work on the motor recently, including around the alternator?
One (or more...) of the alternator bracket bolts goes through the timing chain cover. The cover serves as a plug for the main oil gallery on that end of the motor. If the seal is broken there (there is a circular area of the gasket for sealant around this gallery), the pressure will leak off.
This happened to me some years ago. I must have not tightened all of the alternator bracket bolts properly. The oil broke past the seal, and after that happened, I could not tighten it to stop it. The behavior was exactly as you describe. Cold, thick oil gave me good pressure (I had a gauge...), but when it warmed up, 28 PSI at 3000 PRM was the best I got, vs 40+ as standard. Rod knock set in, and I swapped motors out shortly thereafter.
_______________________________________ Current: 2002 9-5 Aero Kombi Cosmic Blue 2000 9-5 SE sedan, Imola Red 1990 900S Rose Quartz, Auto Past: 1999 9-5 LPT Combi 1999 9-5 LPT sedan 2002 9-5 Arc 1990 900 5-speed 1986 900 turbo Convertible 1991 9000 turbo 1980 99 GLi 1986 900 turbo 1986 900 S 1991 900 turbo 1984 900 turbo 1976 99 GL
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