[urq] general overheating question

[Keith]

Many thanks for all the suggestions and advice. Following day one 
(henceforth regarded as a "clutching at straws day") when I made the posting 
seeking your help and guidance, I continued to investigate and discovered 
the following: -
Fitted brand new reservoir cap
Ran car up to 90c and over.
Coolant reservoir contents remained cold. (opened this with engine stopped
and dipped finger but whilst gauge showing car to be overheating )
Top hose was hot.
Hose from coolant reservoir down to bottom of rad/bottom hose was cold.
Radiator felt cold
Water hoses to oil cooler were hot.
No coolant loss during these tests.
No water returning to the reservoir via the small bore pipe.
Still no heat at all from heater/climate control.

Then following much research on the net which only sought to confuse because 
of conflicting opinions on symptoms/causes and the fact that many helpful 
videos are for the A4 with the 1.8T or the A6 with V6's or V8s none for the 
A6 with the 1.8T, I gave up, weeded the garden and mulled it all over.
Today I dived in and started with the thermostat...took out the old one 
(which is less than a year old), tested it in a saucepan. It opened as it 
should at 87C. But as luck would have it, if you have a long enough fingers 
you can feel the water pump impellor through the thermostat aperture (after 
having removed the thermostat). If you can turn or move the impellor it is 
kaput. Mine felt as though it has fallen to pieces. So at least I now know 
what the problem is. I hope it has not seriously broken up and sent bits 
around the motor.
I've been and bought a new water pump, this time with a metal rather than 
plastic impellor) and timing belt kit (tensioner and idler etc) and have 
started to make my way in towards the water pump. Nothing has given itself 
up easily so far. I never thought I'd say this but in comparison, I now see 
the urq is a joy to work on. In many ways "progress" in cleverly packaging 
engine bay components has become inverted. I guess all is fine as long as 
nothing goes wrong.

Thanks again for the help. I really appreciate it.
All the best

Keith

'87 WR  which has been great in getting to the motor factors for the A6 
bits.....sunny day, shades, fast car, Fabulous Thunderbirds on the 
player.... not so bad after all eh? Time for a beer.



-----Original Message----- 
From: Keith
Sent: Thursday, August 15, 2013 6:20 PM
To: urq at audifans.com
Subject: [urq] general overheating question

Evening All

Apologies for this being a bit off (urq) topic but I could really do with a 
bit of general diagnostic help with an overheating issue on our Audi A6 1.8t 
(2001).
The symptoms are:
Sudden overheating issue.
No steam
No bursts
The coolant level had dropped a little but there were no obvious leaks 
although there was some coolant on the lip of the coolant reservoir 
suggesting that this might have blown out past cap through overheating. The 
low coolant level alarm sounded when this all occurred which drew my 
attention to the temp gauge. Got towed home to hopefully now fix it.
The oil seemed to have got hotter than normal too.
Bought new filler cap to rule this out.
Then.....
Starting from cold, it rises very quickly to 90c (normal operating temp), 
hangs there for a bit and then goes on rising.
Viscous fan and electric fan both working fine and when they are supposed 
to.
Heater just blows cold air even when overheating.
Whipped plugs out – all normal colour.
Tops of pistons look normal – no evidence of steam washing.
No obvious evidence of oil in water or water in oil.
Engine starts fine and runs as smooth as normal.
Thermostat is less than 12 months old. Changed when previously car was not 
getting warm!

My two main suspects are thermostat despite it being almost new and water 
pump.
Have I overlooked anything simple and blindingly obvious?
Before I start taking it all apart though, what can I do to narrow this down 
to the the definite culprit?
I really need to fix this by Monday when I have to use it for work (no 
pressure eh?) so any suggestions of next steps will be greatly appreciated 
(as always).
Cheers folks. Will look forward to hearing from you.

Keith
‘87 WR


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