93 100 CSQW: Overheating / Coolant Loss

[Huw Powell]

> Car currently has 132K. Replaced the thermostat once a long time ago---maybe
> around 60K.

sounds overdue to me.

> I should add that the fan did not come on during the driveway idle test
> (30-45 minutes) yesterday. I attributed this to not reaching sufficient temp
> to trigger that. When I got the warning light at work this AM, the fan was
> running. Also the fan does come on when I hit the AC compressor.

do all the fan speeds work?  That *may* be an issue, I'm not so familiar
with these 3-4 speed fan cars.

> I thought if the thermo was bad, that I'd get no heat, which I do. Heat
> seems normal.

the heater core is independent of the thermostat; it gets hot coolant
all the time.  A thermostat that does not open would yield a cold
radiator, at least at the bottom.

A partly opening thermostat might allow some cooling, let the fan run,
etc., without letting enough coolant into the radiator to properly
control the engine/coolant temps.

Since your thermostat is 70k old, that would also seem to indicate
really old coolant to me.  This would be a good time to replace both,
and perhaps take a good look at the hoses, remove and carefully clean up
all the sensors that go into coolant, that sort of thing.

> thermostat not opening, or radiator fan not coming on, with any luck.
> Easy "outside the engine" things to fix.  If it is a head gasket it will
> be more work and money.
>
> There was some chatter here about testing radiator thermo switches, and
> wiring, about three weeks ago I think.  When was the last time your
> thermostat was changed?  A new one couldn't hurt...
>
> --
> Huw Powell
>
> http://www.humanspeakers.com/
>
> http://www.humanthoughts.org/

--
Huw Powell

http://www.humanspeakers.com/

http://www.humanthoughts.org/