Overheating n drilling the thermostat

Brett Dikeman brett at cloud9.net
Fri Jul 5 16:30:21 EDT 2002

At 11:20 AM -0600 7/5/02, Edward J Kellock wrote:
>I'm having the same issue with my 89 200q.  I've replaced the Sierra
>coolant with Pentosin coolant on the advice of a friend who has found
>that the Pentosin runs much cooler than others.  I have found this to be
>true as well, until the outside temp is way up, 90+.  Once the car gets
>up to the bold mark at about 12:30, 1o'clock position, it doesn't seem
>to want to cool down.  I replaced the thermostat and noticed another
>bit of an improvement.  The car comes up to normal temp more slowly
>now, but can still climb beyond that and not seem to want to return.
>It has never gone much past the higher bold mark on the gauge, but
>it doesn't seem to want to come back down either.  My radiator (as
>well as the previous thermostat) is a little over 60k and 5 years old.
>Could I need a new radiator this soon?

If you are concerned, I'd have a radiator shop remove and service
both radiators, and clean out the A/C condenser while they're at it.
Take the opportunity to insert a copper sleeve inside both of the
larger fittings to strengthen the necks so they don't break; rough up
the mating surfaces to give the epoxy something to grab on to.

As for drilling holes, there should already be a small hole in the
stock thermostat from what I'm told; the purpose is to allow some
coolant to circulate to avoid sudden changes in temperature when the
t-stat does open etc.  I wouldn't modify it further(just a guess, but
that hole might be sized "just right" for something.  Then again,
this is Audi :-)

"They that give up essential liberty to obtain temporary
safety deserve neither liberty nor safety." - Ben Franklin

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