overheating

carolinus · 12-30-2002, 03:14 PM

My 83 944 just started overheating out of the blue yesterday. It had been sitting for a week in the cold, and then I began to drive it home and it started to overheat.

Here are the symptoms:

1. The fans do not turn on until almost the red line on the indicator. They do not cool the system much when they do come on.

2. I cannot detect much in the way of water flow through any of the hoses. The one on the top seems flexible all of the way to overheat.

3. After turning the car off, a lot of coolant flows into the overflow container.

Driving the car has little effect on whether it overheats or not. It usually runs on bar 1, and will then move to bar 2 and the fans come on to bring it back down to about bar 1. It only did this when I was idling or in heavy traffic.

What do you recommend?

adrian jaye · 12-30-2002, 03:26 PM

try Not Just Porsche

details in signature

letrz

Trevor · 12-30-2002, 03:28 PM

I'd check the thermoswitch since the fans still do work. Normally if the switch was totally fried the fans would either stay on or off, could be the thermostat, that is a pain to change.

carolinus · 12-30-2002, 03:30 PM

Are the fans needed to prevent some sort of escalation of engine temp? AKA, if they were not working at all, would driving normally on the freeway in 50degF weather still cause the vehicle to overheat?

Trevor · 12-30-2002, 03:53 PM

I didn't think about that, how is your water pump, any fluid under your car?

carolinus · 12-30-2002, 04:15 PM

Water pump is 30k old. Not much in the way of fluids under the car. Maybe a little antifreeze, but you can see it leaking out of the joint between engine block and thermostat housing.

Just ran another test on it. The fan was wired on, and the system still did not cool any. The needle kept going up.

Should it make a metallic clicking sound when you pinch the lower hose? Sounds like the thermostatic popping back and forth.

Gonna try changing the thermostat tomorrow. Any recommendations for that procedure?

Hope it isn't the water pump. Why didn't they put the thermostat in the top hose joint? Maybe somebody could make a retrofit...

Lawrence Coppari · 12-31-2002, 09:57 AM

fans needed?
Are the fans needed to prevent some sort of escalation of engine temp? AKA, if they were not working at all, would driving normally on the freeway in 50degF weather still cause the vehicle to overheat?

Fans, in general, are not needed when the car is being driven on the highway. If it overheats on the highway, you either have a bad water pump, stuck thermostat, or a clogged radiator, or some or all of the above.

carolinus · 12-31-2002, 10:23 AM

The thermostat was starting to literally come apart. I am putting in a new one right now. BTW, that snap ring is the most evil think I have ever encountered in my life.

I will keep you guys posted as to if this solves the problem.

Lawrence Coppari · 12-31-2002, 11:30 AM

Sounds like you have gotten the infamous snap ring out already. Impressive. It took me an afternoon.

carolinus · 12-31-2002, 12:09 PM

The ring was removed using a pair of 45deg pliers (just needle nose pliers with fine tips, not snap ring pliers) and a set of vice grips. The vice grips are used to ping the needle nose pliers closed, and then the ring is removed. The teeth in the needle nose plier tips are what really helps.

Unfortunately, the car is still overheating. It does not appear that there is any water flow through the engine. Both hoses are empty of water, and it is very difficult to get the correct amount of coolant in the system. What do you guys think it is? Please don't say water pump... BTW, I did put the thermostat in there correctly. It still sounds like thermostat not opening, but I checked the new one. Blockage in radiator?

Scott R · Scott R's Garage

Blocked radiator, or bad pump. Possibly excessive air in the system.

What procedure did you use to bleed it when you replaced the thermostat?

carolinus · 12-31-2002, 03:41 PM

I think it was excessive air. I started the car, let it run, shut it off, and then opened the reservoir and the air vent. This allowed more coolant to be added. Eventually, it started to work correctly. I think my problem was that the previous mechanic didn't put in the thermostat o-ring, and that allowed all of the coolant to exit the system when I drained the radiator. This meant that the new thermostat had nothing but air surrounding it. Filling up the engine block manually was what really seemed to do it.

Thanks for everybody's help.