87 5k sq running hotter than normal

[Doyt W. Echelberger]

Hello Dave............You may not have a cooling system problem. Depends on 
what you consider normal, and how you measure it. I use my dash temp gauge, 
and you probably do also.

My 1987 5ktq runs a little past mid-dial in the summer. When the cool 
weather arrives, it runs about mid-dial. When I stop moving in traffic, or 
let it idle in the driveway, the radiator fan comes on, runs awhile, and 
stops, then it does it again. I don't worry about that. Maybe I should. 
But, let's move on and assume there is a problem. Where do you start looking?

I'd inspect the radiator fins by looking through the grill with a 
flashlight, to determine if it is blocked by bugs and fuzz and other stuff. 
I'd take a close look, and try some high pressure external spray from both 
sides to make sure the air can move through the fins. That would be my 
first step. Then I'd drive the car and see if it ran cooler.

OK, maybe that doesn't change anything. On to plan "B."  Flush the system 
and see what comes out. The coolant is probably old and in need of changing 
anyhow. If you know how long it sat, and have good records of maintenance, 
you could estimate that possibility. 3 years would be my limit on letting 
coolant go unchanged.

As part of the drain and change, you could remove the thermostat and test 
it, and replace it if necessary, along with any coolant hoses that feel 
soft.  I'd also replace the heater control valve with a metal one from 
Autozone. The original plastic valve has a record of catastrophic failure 
at about the age of your car. I replaced mine last year, before it failed.

Doing the above maintenance won't hurt anything and is probably a good 
idea. But the system may go right on doing what it is doing.

If you put the system back together and it still behaves the same way, and 
this still concerns you, then maybe the water pump is at fault or there is 
a restriction in coolant flow, or the radiator core is crudded up inside 
and the heat can't move from the coolant to the outside. The engine itself 
might have a heat exchange problem due to internal water passage foreign 
materials/rust build up.  These are conditions that I would take to an Audi 
mechanic for diagnosis. Based on that professional opinion, I might replace 
the radiator myself, if the specialist indicated that it was necessary. I'd 
have the water pump and timing belt replaced by a professional.

That covers about 3 levels of action. It gives you  some things to consider 
and agree or disagree with, and I hope it helps you with whatever you do. 
And I hope that you let us all know what you do and how it turns out. Good 
luck.

Doyt Echelberger
87 5ktq  205k miles

 >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
At 03:04 PM 10/9/2001 +0000, you wrote:
>I have an 87 5000S Quattro that has not been driven much as of late and it 
>seems to be running hotter than normal but does not overheat.  Even while 
>driving, the temp seems to hover right at the point where the aux radiator 
>fan comes on.  Any good ideas as to where to start in my quest to lower 
>the temp?  Thermostat? Radiator flush? What?
>
>Thanks in advance!