Date: Sat, 31 Aug 2002 17:39:52 GMT From: Daniel Davis <dandavistxnopsamo.com> Subject: 900 Turbo over pressure switch
a little history first... 85 900 turbo. I've had a hissing soung (air rushing out) from inside the dash for several weeks now but I can't remember if the sound is normal. It only occures during boost and gets louder the more boost there is. I tore apart the dash and traced the vacuum line coming in from the firewall (not the line coming in from the fender) and it splits to 2 end points: 1. the APC Pressure sensor 2. the APC Guage on the dash after passing through the over pressure switch I've traced the sound to the over pressure switch (part 8594632) which is just a pass through whith the center nipple getting vacuum from the engine and the outer nipple passing it through to the APC guage on the dash. The problem is that it will hold vacuum but will not hold pressure. This is not a problem during normal driving when the intake manifold is in a vacuum state (negative boost), but when I gun the throttle and the turbo is boosting the intake, this little switch makes a wondurful hiss. and my APC guage will not go up to the line between the red and yellow since the pressure is being lost. Question: is it suposed to leak ans hiss at positive pressure? I don't recall it ever doing this before but I want to double check before I go out and spend $105 (at www.thesaabsite.com) for a new switch. Thanks for any comments in advance Daniel
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