90Q overheating

[Matt Evans]

The B3 90Q has a 13mm (wrench size) bolt on the primary radiator that acts
as a bleed screw for the system. 

> -----Original Message-----
> From: quattro-bounces at audifans.com 
> [mailto:quattro-bounces at audifans.com] On Behalf Of Tyson Varosyan
> Sent: Monday, January 31, 2005 11:37 PM
> To: 'Duncan Thomson'; Quattro at Audifans. Com (E-mail)
> Subject: RE: 90Q overheating
> 
> 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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