It is possible for an external coolant leak to allow air to enter the system. When the system cools down, it will pull a vacuum as the coolant contracts. This is how coolant is returned to the system from the recovery tank. A leak of the correct size and location will allow this. The ones I have come across are the hose connections for the large coolant pipes and a leaky from heater core. Also, you need to make sure the pressure cap is functioning properly, both the pressure relief and return valve. A sticking or clogged return will cause the system to try to suck in someplace other than the recovery bottle. Dennis
-----Original Message----- From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Doug F Sent: Saturday, April 01, 2006 9:26 PM To: vanagon@GERRY.VANAGON.COM Subject: Re: Air Getting into Cooling system How? A compression test will not reveal a tiny leak which is plenty to pump up the cooling system with air. I had this exact same problem with my 85 sunroof GL. Got progressively worse because air in the system continues to overheat stuff. Eventually it got so bad I had to admit it was the heads. The cooling system runs pressurized so any leaks will not allow air to enter but instead create a leak of antifreeze on the ground. Betcha a nickel its the heads. Doug
Doug ----- Original Message ----- From: "John Connolly, Aircooled.Net" <john@AIRCOOLED.NET> To: <vanagon@GERRY.VANAGON.COM> Sent: Saturday, April 01, 2006 6:06 PM Subject: Re: Air Getting into Cooling system
> head gaskets are fine, already checked that. > > John |
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