On Mon, 21 Jul 2003, Jay L Snyder wrote:

> I made up a fitting that attached to the radiator bleed bolt that ran to a
> vacuum/30 psi gauge.  I wanted to see what the system pressure actually ran
> at during normal driving.  It ran higher than I thought, reaching 14 psi
> when hot, near, or at the set point of the pressure cap.  I assume there
> was some push over into the overflow tank?

That makes sense. My Vanagon, like most cars I've owned that had coolant
recovery bottles, will push coolant into the bottle when driven and suck
it back a few hours later when it cools down.  I've had some cars where
the level of coolant in the recovery bottle with the engine cold would
even vary noticably with the outdoor temperature.  I'd actually be
concerned if I *weren't* seeing coolant pushed into the bottle, since to
me that would suggest low coolant level, a bad cap, or a pressure leak
somewhere.

I used to have a '90 Econoline that had no recovery bottle.  You had to
leave about two inches of air space in the radiator for thermal expansion
or it would puke a bunch of coolant onto the ground the first time you
parked it after driving it hard.  I eventually added an aftermarket
bottle.

David Brodbeck, N8SRE
'82 Diesel Westfalia
'94 Honda Civic Si