[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

Re: Idle Stabilization Valve correct operation

Mirrors my experience.  Except that I broke my coolant bleeder screw today
while changing the fluid - damn plastic.  :-(  Temporarily replaced with a
bolt.  "Placebo", huh?  Better than "Ibizia" or "Octavia"...

At 08:43 PM 8/16/1998 ,  Phil Rose was inspired to say:
>  Now I've had a chance to peer into the bowels if my '91 200's ISV, and I
>  revise my earlier suppositions. I, too, see an opening about the width of a
>  nickel (uh, about 1.25 mm--for the numismatically challenged). There was
>  quite a bit of black crud showing on the cylinder surface, but application
>  of 9V could move the mechanism easily to and fro. Many on/off cycles failed
>  to diminish the size of the ISV opening at the "rest" (off) position. I
>  seemed to hear the rotation stop with a resounding "clack" as the shutter
>  hit the limit screw.
>  I applied several squirts of carburetor cleaner. I repeated the 9 volt
>  jolts some more, and convinced myself that things were moving freely and
>  weren't gonna change. The opening _could_ in theory be closed up by use of
>  the potted adjustment screw. But why? Could the original adjustment
>  actually have "worn" away to the extent of a 1.5 mm opening? I think not.
>  The adjustment screw has a broad, flat end, and I doubt Bosch would be dumb
>  enough to have designed a "pointy ended" screw for this application. So I
>  think the ISV opening is the way Bosch set it to begin with. Also it's
>  cemented in place and virtually impossible to turn (as reported by Brett).
>  If the screw _could_ be turned, its fine thread would require at least 3
>  full turns to eliminate the "gap". I left it alone and reinstalled the ISV.
>  Damn, I think the car runs better. Maybe I oughta rename it "Placebo". But
>  that sounds a little too Spanish for a German car, dontcha think?

	88 90Q - <insert pithy witticism here>
	88 Golf GTi - PRO Rally