Car Stuck! Engine Coolant boiling over

[SJ]

I got lots of responses to my cry for help.

All the advice is centered on the cooling fan . . . which I dont think is
the problem.
Even when the cooling system is working properly, the cooling fan never
kicks in during first 5 or 10 minutes of idling. The fan wont kick in until
the temperature guage goes well over the halfway mark.

Once again, the symptoms are a normal running engine, when all of a sudden
you get an explosion of hot water and steam erupting from the overflow tank.
The temperature guage only indicates about 1/3 up.

This is not a gradual heating up of the cooling system. The water hoses just
before the event are hot but not that hot . .I can put my hands on them.
This looks more like water sitting in the engine until it gets to the
boiling point . .. then flashes over into steam and the steam forces the
water out of the engine thru the hoses, thru the radiator and water erupts
out of the expansion tank. This looks more like its caused by water that is
not circulating.

A non functioning water pump would do that . . .or blocked thermostat. Thats
what the symptoms indicate to me.

Bob mentioned a leaking head gasket. I did not notice any gas leaking out of
the expansion tank. Besides, if gas can get into the water . .water should
be able to get into the gas . . .the car would be exhausting clouds of white
vapor.

I'll test the fan tomorrow by jumping out the temperature switch at the
radiator. I'll take a spare temperature switch with me.

Another odd symptom comes to mind. While I was working on repairing the
leaking brake line, the cooling fan would come on for a minute or so. The
engine was not running, nor was it run for 2 days. The car had been up on
jackstands for 2 days. I noticed this twice, the fan came on with a cold
engine. Ambiant temperature was about 80 degrees.

Even with the cooling fan not working, if I get the car onto a highway in a
few minutes . . .the air rushing thru the rad should be enough to cool the
engine. I've never seen the temp guage go over 1/2 when driving on the
highway. The only time the guage goes over 1/2  and the fan kicks in is
during stop and go city driving.
In other words, I dont need the fan to get me home via highway driving. Any
comments?

What are the odds of a water pump failing in such a way that it stops
circulating water?


SJ
85 Dodge PU, D-250, 318, auto
85 Audi 4k - - sold but still on the road
88 Audi 5kq
90 Audi 100q


----- Original Message ----- 
From: <SuffolkD at aol.com>
To: <quattro at audifans.com>; <syljay at optonline.net>
Sent: Sunday, May 23, 2004 10:17 PM
Subject: Re: Car Stuck! Engine Coolant boiling over


> Fan should come on.  Check fan relay, temp switch or see if that 100 has
the
> fusable link on the drivers side wheel well (in the engine compartment) It
is
> two phillips head scresw with (or without later in life) a plastic box
over
> it.  There is a thin blade or metal (fuse) that goes between the two
screws
> which when cracked or blown, keeps the fan from running PERIOD.
>
> POSTING a picture would make this O - Soooooooooooooo much easier.  If I
find
> one I'll send it off list.
> -Scott by BOSTON
>
> > From: SJ <>
> > 90 100q, normally aspriated, manual
> > snip
> > My hunch is a stuck thermostat.
> > I will pick up a new thermostat and gasket and go to where the car is
stuck
> > and attempt replacing the thermostat in the parking lot.
> >
> > As I recall, unbolting the hydraulic pump and moving it aside opens up a
lot
> > of access room to the hoses and thermostat housing. After that, one has
> > access to the two thermostat housing bolts.
> >
> >
>
>
>