[urq] boiling coolant after shutdown

[Ed Kellock]

Well, this seems to have been the answer.  I tightened down the cap
and drove home and no boiling in the upper hose.

I took a few minutes and found the proper temp sensor for my VDO gauge
to read correctly, went for a drive, then watched it intensely as it
idled in the driveway and cycled through fan on/fan off.  Went for
another drive and shut it off when I pulled in and parked.  Again no
boiling.  And no leaks.  Nice and cool today though, but I feel pretty
good about having finally "resolved" the cooling situation.

Thanks!
Ed

----- Original Message ----- 
From: <Louis_Alain_Richard at computerhorizons.com>
To: "Ed Kellock" <ekellock at gmail.com>
Cc: "Urq List" <urq at audifans.com>; <urq-bounces at audifans.com>
Sent: Tuesday, July 26, 2005 11:03 AM
Subject: Re: [urq] boiling coolant after shutdown


> My first culprit would be the reservoir pressure cap (or another
small leak
> permitting a lower system pressure).
>
> Following a lister suggestion, I made a low pressure cap (by cutting
the
> spring inside) to give the cooling system a break. Like you, I had
many
> leaks one after the other. My problem with the low-pressure cap was
exactly
> like yours; at shut-off, I was clearly hearing boiling in the head,
by
> burst. I guess the cap must have a good pressure to prevent
localized
> boiling around the exhausts valves. When I put a new cap, and did
> sufficient cycles to completely bleed the system (which is
(notoriously ?)
> hard to bleed), no more boiling issues.  And no more leaks either...
>
> HTH,
>
> Louis-Alain
>
>
> "Ed Kellock" <ekellock at gmail.com> wrote on 2005-07-26 12:46:30:
>
> > It's very cool here this morning for a change so I decided to
drive
> > the urq to work.  I had the heater valve wide open and the engine
> > temperature never exceeded normal, the cooling fan did not come
on,
> > even with a minute of idling after reaching work.
> >
> > Inside the hose from the neck on the front of the head that goes
to
> > the top of the radiator, the coolant was very obviously boiling.
Is
> > this even remotely normal?
> >
> > History: On June 25th, at 3am, I was on my way to meeting everyone
to
> > go up the road to the Pikes Peak Hillclimb.  I had been driving
the
> > car regularly prior to that and it was running great.  It was
cool,
> > jacket weather still in fact, and I drove very sedately for about
5
> > miles, stopping off at a 7/11 for some coffee.  When I restarted
the
> > car to leave, the coolant low level warning was on.  A leak had
sprung
> > under the clamp on the lower rad hose at the thermostat housing.
I
> > refilled and drove a few more miles to the meeting place.  I
stopped
> > and refilled and then drove a short bit more where I finally
ditched
> > the car at the gate of Pikes Peak and rode up with Bruce Bell.
Later
> > that day, I retrieved the car and drove very carefully and
> > uneventfully home where a couple days later, I replaced the
offending
> > hose with a spare from Ben Howell (Thanks Ben!) along with a new
lower
> > temp thermostat and a new thermo-time switch at the back of the
head.
> > The next day I drove to work and another leak sprang, in the hose
that
> > goes from the bottom of the coolant recovery tank to the bottom of
the
> > radiator. I replaced that.  The next day the throttle cable came
loose
> > from the pedal in a store parking lot during a hail storm, which
being
> > the third strike in less than a week signalled the beginning of
the
> > cooling off period between the urq and I.  Since then I have only
> > driven the car home from that store, one quick trip around the
> > neighborhood a week or so ago and then to work today.
> >
> > The boiling in the hose was present back on June 25th, but I
figured
> > it was merely a product of my low/leaking coolant tribulations
then.
> > Now, the system is leak free, with a new thermostat, which
obviously
> > opens earlier and causes the car to run cooler, and the temp on my
way
> > to work this morning was sub-70 and my drive was not spirited,
except
> > for one light blast short-shifting into 2nd, then 3rd, to keep the
> > boost from falling off.  That wasn't more than a couple hundred
yards,
> > followed by at least a half mile of 4th and 5th at 40 mph or so.
> >
> > If you've read this far, thank you, and I appreciate any
thoughtful
> > input you may have.  I'm thinking head gasket, but I tend to be
> > overreactive and paranoid sometimes, so I'm hoping that's the case
> > again this time.
> >
> > Ed