4kq overheating - still

[ben swann]

Huw,

I thought I was clear in prior posts that I have replaced the water
pump.

I am at a loss to figure how the pump I took out is bad as I could not
move the impeller independantly of the gear.  It would also be a very
strange coincidence that the new one I installed is bad.

I have also replaced 3 times - the radiator.

Also the thermostat.

Also the fan switch.

I have partially attempted to flush the engine, but my method may not
be correct which I am suspect.

Yes the engine operates as if there is no water pump, but I think we
need to rule that out already.

So it is a big mystery to me and I would begin to part the car out if I
had not already done so much work to it and it just went through MD
inspection.

Next step - replace the engine?  Pull the head and I'm halfway there!

Ben
1 NG motor ready to install in empty bay of 4kq "Project GTQ"(not the
overheating one) and 1 freshly pulled '87 4kq engine looking for a new
home but don't quite want to fo there yet.

----- Original Message -----
From: Huw Powell <audi at humanspeakers.com>
Date: Saturday, May 31, 2003 11:24 pm
Subject: Re: 4kq overheating - still

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/