Re: Coolant Problem/Thermostat location? '92 100

[Todd Young <tyoung@wamnet.com>]

"Craig D. Niederst" wrote:

> I am currently having the same problem with my '92 100S. I do not believe
> the thermostat is the problem here. My water pump had starting chirping a
> few of months back, so I had it replaced along with the thermostat.

YES! Very important, if that water pump locks up, bye-bye timing belt (and
valves!). Chirping is the warning sign that the water pump is about to lock up.
BTDT, but I caught it before the timing belt broke.

> I hoped
> replacing either the water pump or the thermostat would solve the mysterious
> coolant loss / erratic temp gauge problem, but no luck.

My 90SV6 has an erratic gage, as long as it doesn't go above the half way mark,
I ignore it.

> If you are actually
> having the same problem as I am, you are losing coolant through the cap on
> the coolant reservoir. It has a pressure release feature built into it, and
> when pressure exceeds the limit, it comes out through the cap so a hose, etc
> will not rupture.

Have you tried replacing the cap on the expansion tank? Just like a "normal"
radiator cap, they can go bad, and then will not hold the required pressure in
the cooling system.

> Two said I had a bad
> head gasket or cracked head, and exhaust gas was getting into the coolant
> system, causing the higher pressure condition.

Any reputable auto repair shop should have a "sniffer". This is a tool that has
fluid that is sensitive to HC that would be present in you cooling system
IF you had a headgasket leak. The coolant cap is removed, the engine is brought
up to operating temperature and then air from the cooling system is drawn into
the tester. If HC is present, the fluid in the tester changes color.


--
Todd Young              WAM!NET Inc.
tyoung@wamnet.com       6100 West 110th Street
612-886-5051            Bloomington, MN 55438-2664
800-585-1133 ext.5051   http://www.wamnet.com/
'93 Audi 90S(|___\====OOOO====/___|)