Overheating: Please Help - AX in 7 days!!

[HDBrown]

I've had '83 944 (w/ 70k orig mi) for a month. Its never shown temp over 1/2 guage and PO was a good maintainer.

Yesterday the temp guage pegged, (under cool normal driving conditions) and coolant boiled.

I read up on bleeding the system (thread on this site) and did so 4 times using the "hose squeeze" method and the "blow through the drain tube" method.

Once the car reaches op temp. it rapidly (less than 2 min) goes from normal to overheating.

The upper and lower hoses both feel hot. So I am assuming I am getting "flow".

Once the car starts to overheat, coolant flows backward through the overflow tank and out of the overflow tube. This evacuates around a quart and more air enters the system.

Water pump is updated version with 18k miles on it, buT 13 years old.

Thermostat condition unknown and my next step of investigation; but my ASSUMPTION is since both upper and lower hoses and radiator are hot, that the thermostat is opening.

The heater works properly and blows hot air.

Water pump is not seeping and not making noise. I tried squeezing the upper hose to feel "surge" but could not really tell.

There is not water, bubbles or emulsification in the motor oil; no white smoke from the exhaust or on startup.

I'd really appreciate any help on diagnosing this. Thanks!!

[Trevor]

Are the fans kicking on? The water pump sounds VERY old, when was the last time the belt was done?

[Lawrence Coppari]

Thermostat might not be opening enough. I had one of my cars do this to me. Is the hose on the intake side of the radiator hotter than the one on the exhaust side? No temperature drop implies no cooling between - ie plugged radiator.

[bazar01]

The upper and lower hoses both feel hot. So I am assuming I am getting "flow".

Your radiator cooling fan may not be running.
It should kick on at 92C, between middle and third line on the temp gauge.

[HDBrown]

Gents, thanks for the initial feedback.

The top hose feels hotter than the bottom hose, but they are both hot.

The left engine fan is cutting on, not sure about the right.

The car just had a pre-purchase inspection, belts look new, and did not merit comment in PP insp.

Radiator is 10 years old; supposedly a "turbo's" radiator.

My plan is to pull the thermostat out tomorrow morning check it in hot water on the stove and see how the car runs sans thermostat.

Any other advice out there?

Hank

[AFJuvat]

Sounds like you have a bad thermostat

AFJuvat

[McClintock16]

I have a related question. The driver side rad. fan comes on, but even at very hot (siting and idling in stop and go traffic) the pass. side NEVER comes on. Im thinking fan relay maybe??

[ernestedward]

It's only supposed to come on when you turn on the A/C.

[Britwrench]

It comes on without the AC being on, of course, it is also AC regulated too. For the early dash 944 you will need a new relay.