4kq overheating - still

[Huw Powell]

> I have been at this overheating problem in a '85 4kq for too long and
> this problem perplexes me.  I am beginning to think the problem maybe
> internal to the engine.

[all info snipped for total unintelligibility!]

Ben, I have been thinking about this for hours, days, trying to diagnose
it at my keyboard.  Following on from some hints along the way (other
answers, your other posts), I think what you have a non-functioning
water pump.  In fact, I am pretty certain of it.

You have ascertained that all passages pass fluid - even if a little
blocked, they would still pass some hot coolant.

The existence of pressure everywhere also shows this.

The pressure is not due to the water pump, it is due to the coolant
heating up  (I doubt the water pump creates much a pressure gradient in
the system anyway, but what do I know?)

So the coolant all sits there, getting hotter, pressurising the system,
but does not move.  Busted water pump.

You get a little heat in the passenger compartment due to convection, I
figure.

here is an interesting test, if you still like to run that engine while
risking all the parts that don't like extra heat (although this test can
be done cold, so it's ok).

With the thermostat out (so it can be done cold), turn engine on.

Go under the hood.  Look closely at the coolant expansion tank.  If you
can see through the plastic, so much the better (if not, get a new one).

Rev the engine up - you should see coolant spraying into the x-tank from
the small hose attached to the top of the radiator.  You can do it with
the cap off if the tank has become opaque with age.

No flow there >>>  Water pump bad.
Flow there >>>  Look up obscure pagan rites to exorcise your engine...

If the pump really does work, something must be blocking a difficult to
test passage that prevents any flow from occuring.  Either way, I think
you need to excavate the pump and take a look.

--
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/