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Subject:Re: Purging Cooling System
From:Dan Houg
Date:Sat, 14 Jan 1995 16:19:14 CST6CDT

Gerry wrote:  
> 
> At one point after getting some clear sign of air bubbles, the radiator fan
> came on and shortly after, nothing came out of the bleed screw for a 
> while even though it was wide open. Do I have a plugged radiator?
> ????
> Then after a while, it started coming again.
> 
> 
What is probably happening is that when the rad fan comes on it cools 
the coolant down, decreasing its volume (more dense at cooler temps) 
and reducing pressure enough in your system to stop flow out of the 
bleeder valve.  The effect of the fan coming on with respect to the 
volume of coolant can be observed on a 'normal' car with a radiator 
cap ontop the rad.  Watch the coolant level take an immediate dip 
(rad cap off, peering inside filler neck) when the rad fan comes on!  
It resumes the pre-fan level or higher when the fan switches off.

Daniel Houg
Minnesota Department of Health
Internet Address:  fairwind@northernnet.com
Fax #:  218/755-3823