Date:         Tue, 26 Aug 2003 09:54:05 -0400
Reply-To:     SStones <sstones@IDIRECT.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         SStones <sstones@IDIRECT.COM>
Subject:      Re: Overheating while bleeding?
In-Reply-To:  <000001c36b98$725a7e00$e944530c@swhome2>
Content-Type: text/plain; charset="us-ascii"; format=flowed

>Where you running at around 3000 rpm?


>Fricking frackin van.  My 86 2WD Westy has been running a little warm
>(have to turn the
>heater on sometimes) so I figure I'd better bleed it to be sure there's
>no air in it.  So I park it
>up on the ramps, expansion cap off and it's up to temp, but I'm getting
>nothing from the
>thermostat bleed screw, some air from the rad, but I can tell if it's
>going in or coming out
>(coolant starts siphoning out of expansion tank?).
>
>Anyways, before getting any coolant out of the thermostat bleed screw or
>radiator bleed
>screw, my coolant boils over!  What a mess!

Up on the ramps, the top of the radiator is much higher than the top of the
expansion tank.  If there's a hole to atmosphere at both of those points
(Open cap and open bleed screw) air will rush in through the radiator bleed
screw to replace the coolant flowing out through the open expansion tank.
By running the engine at 2500+ RPM, you can create enough flow to force the
liquid up, into and through the radiator so that the system can be bled
with two holes open it it at once. People do it this way to save time.
I still believe you're best off bleeding all the low points first and
working your way up to the final bleed at the radiator. You will get more
of the air out, and the constant positive sealed pressure on the hottest
engine surfaces will help prevent damage from warping caused by the drop in
heat-conductivity from the bits under the coolant-vapour spots. It's never
a good idea to let your engine be that hot without pressure in the cooling
system. The vapour bubbles insulate the metal.  Time isn't money when
you're doing your own work on your own vehicle.