JKrevnov@aol.com wrote:
>
> In a message dated 2/11/02 12:57:37 AM, tubaman@WOMBAT.NET writes:
>
> << coolant temperature/pressure sensor >>
>
> ?????

if there was something causing the pressure to build up to be over what the computer
thinks is a problem, having the cap loose would prevent that (but whatever is making
the pressure would air vent through the loose cap - when you tighten it, the
pressure builds up again.) The computer assumes high pressure = high temperature -
that was what happened with the  leak problem I had in 1985 - the temp gauge and
warning light would come on, even if the engine was barely warmed up and the system
would go to "limp home" mode. It took a complete rebuild to cure that problem.
bleeding was a temporary cure (I was on a trip around the USA and I had to stop for
system bleeding about every 1000 miles!)

Dave Richoux 83.5 Westy

David Richoux wrote:
>
> "Terry K." wrote:
> >
> > Hey all----
> >
> > Figure this one out---
> >
> > I have been milking a coolant hose leak for 6 mos., it was one of the
> > two that go along the firewall, down to the metal tubes that go forward
> > to the radiator---I just loosened the cap on the expansion tank, and the
> > loss was minimal.
> >
> > The Van has always had a hesitation, when leaving from a stop, until I
> > left the pressure cap loose--and it has ran just ducky-----
> >
> > I replaced the hoses yesterday, and now the darn hesitation is
> > back-----this just can't be----no rhyme, nor reason.
> >
> > Mind you, every electrical control component  has been replaced within
> > the last two years, and now that it doesn't have any post nasal drip--it
> > runs like Ca-Ca--off the line--the juice pedal, has to be stuffed to the
> > floor, before the van takes off with any sort of semblance of
> > speed---and even then it's a bow-wow---
> >
> > The oxy sensor light was blinking prior to me repairing the hoses--now
> > it doesn't.--this alone doesn't sound right----
> >
> > I give---any idea's?
>
> I cannot tell from your message what year van you have, but I learned very early on
> in my 83.5 westy that the coolant temperature/pressure sensor is directly linked to
> the main computer - if it "thinks" things are too hot it will shut down the engine
> (or at least reduce performance ) - so reducing the pressure by loosening the cap
> would have that effect but I don't think it will be good in the long run. you may
> have built up a large air bubble in the system, introduced by the leaks in the water lines.
> (or you may have the classic head gasket/water jacket leak as well! :-(
> Dave Richoux