Miata Mailing List: February 1994, Message #126
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   From: Vlad-Erik Kimsson 
Subject: ISC Cleaning...
   Date: Tue, 8 Feb 1994 11:48:41 -0500

I had the famed ISC problem and attempted to fix it by cleaning.

I took off the ISC (be careful not to strip the screws; they're upside down
and you may need an angle screwdriver) and sprayed carb cleaner in it, letting
it run out to wash out gunk.  There's really no way to disassemble it, so
it seems that you just have to flush it.  When I put it all back together
it solved the problem for * a while *.  The dealer has since replaced the
valve under warranty.

It *might* be good to lubricate it with a light teflon-containing lube
(I'd worry about catching dust on anything oily, though...)
Be very careful with the rubber gasket; it's very easy to let it fall off
with the upside-down mounting geometry.  My car was sucking in coolant
through an adjacent passage and emitting lots of smoke until I figured this
out and replaced it. Even then I ended up using gasket sealer.
I would NOT want to do this with every oil change; though one could.

I really thought the explanation of why this happens was compelling.
Perhaps someone can suggest a way to filter or re-route the crankcase
fumes to avoid this.

(To those not familiar with the layout: You do have to remove some air
hoses and chambers as well as a coolant line or two to  get at it.  Not
too big a deal, just remember to plug everything back in!)

					-Dave Kim