90Q overheating

[Tyson Varosyan]

Duncan,

You likely got air trapped in your coolant system since the fluid was
dumped. Most cars have purge valves to let the air out. I am not familiar
with the 90, but on my 3000GT the procedure called for the coolant tank to
be filled. Then there is a cap directly opposite the water pump on the other
side of the engine - it is to be removed and coolant be topped off from
there. Then while running the car you add coolant. I heard many burping
sounds as air trapped in the system after the radiator removal was being
circulated towards the hole and let out.

Bottom line, if others do note respond with more detailed info, trace your
coolant lines around the car and look for an additional fill cap and/or
purge valve. Open it up, fill the system as far as you can, run the car with
the valve open and keep topping it off until it will not take more coolant -
the system should spit out the extra stuff later via the overflow valve.

If memory serves right, my Audi 4000 has one purge valve (looks like a bolt)
on top of the radiator on the right side. The '88 90Q is a similar car, look
for that and other points for the air to escape the system.

You didn't install your thermostat backwards, did you?

Tyson Varosyan
Technical Manager, Uptime Technical Solutions LLC.
tyson at up-times.com
www.up-times.com
206-715-TECH (8324)

UpTime/OnTime/AnyTime

-----Original Message-----
From: quattro-bounces at audifans.com
[mailto:quattro-bounces at audifans.com]On Behalf Of Duncan Thomson
Sent: Monday, January 31, 2005 9:30 PM
To: quattro at audifans.com
Subject: 90Q overheating


Hi guys,

Have a serious overheating problem on my 1988 90Q. Basically overheating
and then dumping all it's water. Have just changed thermostat, and have
tried radiator cap off my CQ. No change. Fan does come on, but seems to
turn off again even when car is still hot, so concentrating on this for now.

Which sensors drive the radiator fan? Sensor at bottom of radiator? Are
there supposed to be 2 speeds for this fan?

Any help greatly appreciated...

cheers
Duncan


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