Date: Fri, 1 Jan 2016 19:34:02 -0500
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Wondering about coolant physics
In-Reply-To: <CAFnDXk2kkkuWuAUz+ghBxfRomTBZXiTk3TqVTZpa82q5OFfXtg@mail.gmail.com>
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While your van is sleeping at night it is colder at 2-3 am than it is at 8am. So yes before you start it in the morning you are already getting some warming up expansion action. When the caps fail they usually fail so with one of the valves open. Easy enough to test. If you have tablespoons of coolant on the ground you do still have a leak. If you have the original coolant pipes I would begin looking at the hose connections.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Jim Felder
Sent: Friday, January 1, 2016 12:58 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Wondering about coolant physics
Not very important as my car is running and cooling well, but I am curious about this issue which I can't come up with an explanation for.
I recently installed new radiator hoses and with the help of this list, finally got it right by going to a 1.9 waterboxer reservoir on my 1983 diesel.
Everything is good and seemingly snug, but on a cold night like last night and a few before, I find a small puddle, what I always called a "cold leak"
that doesn't appear when the engine is running or when the weather is warmer. It's so slight, I can't really tell exactly where it's coming from, maybe a couple of tablespoons when it gets down around freezing.
When I open the pressure cap, I get a burp of air. This is from cold, no starting or running whatsoever.
How can this be? There's obviously a small leak somewhere around the reservoir, maybe even the cap or a connection or even the coolant level indicator. There just isn't more than a few drops on the hoses to leave a trace. I may powder it with flour dust to find out more about where it is coming from and how it gets to the ground.
But back to the burp: air in the system and coolant in the system is at equilibrium with the atmosphere when it is added, right? Then you drive the car, and it heats up, then the system becomes pressurized which raises the boiling point of the coolant even further. Then the car sits out overnight, and the temperatures the next morning are even lower, so you would expect no pressure or, as the system is designed to take advantage of, a vacuum to suck in coolant from the overflow tank to displace the air, right?
This isn't happening. I suspect it's a crappy blue cap, the second I've bought in two months, is preventing the intake of coolant. But maybe it's because of this residual pressure that I can't figure out. why is there a burp when I open the cap in the morning instead of nothing?
Anyone?
Jim
Jim
