Overheating Problem

Silverbullet951 · 10-17-2002, 07:52 AM

I was driving my car a few days ago and I saw that the temp was going up very fast. It was a very cold day, that's why it surprised me. When I drove, the temp dropped fast, and when I stopped it went up really fast. Oh, and I also hear a whining noise coming from the front of the engine. Could it be the water pump? Maybe there's something wrong with the Thermostat? Water pump relay? Any suggestions? Thanks.

Ps. there is a significant amount of air bubbles in the expansion tank. I don't think it's a blown Hg because I don't smell a sweet exhaust, nor am I losing any coolant. If I turned off the car, it would flood with coolant and not start. It started up right away yesterday. I need help here! Thanks again.

Lawrence Coppari · 10-17-2002, 08:04 AM

I'd get it to the shop quickly if you are not inclined to look at it yourself. The squealing could be the water pump or some idler pulley. The cam belt drives the water pump. You know what happens if the cam belt breaks.

Bubbles in the water reservoir could mean a blown head gasket. If it filled the cylinders with water, it definitely means a blown headgasket.

You need to get it fixed and quit driving it or you'll be in for an even bigger repair bill.

Britwrench · 10-17-2002, 08:07 AM

The temp gauge going up and then down is a sign of lack of coolant = STOP DRIVING IMMEDIATELY.
There is a good possibility that the water pump is leaking and there is no coolant in the engine. This means the fuel injection sensor is not surrounded by coolant and will not register any temperature and therefore will "think" the engine is cold. The computer will then run the engine in cold start mode (rich).

Basically, you need to do a leakdown and compression test of the engine and a cooling system pressure test. If the head gsket hasn't failed right now, it will soon.

Any 944 that has overheated will need; thermostat and coolant sensor for DME. Turbos need the thermostat for the turbo coolant supply. You should also replace the oil cooler/tube seals.

Silverbullet951 · 10-17-2002, 08:30 AM

I'm going to do it myself. i just want to make sure what the problem is. I 'm not going to drive the car at all. The thing is, I checked the coolant level, it's full. That's why I don't think it's a blown headgasket. I will definitely check the belt. It started right after this mysterious whining sound started. How big of a job do you guys think this is? Thanks for the replies. Any further info is greatly appreciated.

Lawrence Coppari · 10-17-2002, 08:49 AM

"If I turned off the car, it would flood with coolant and not start. "

What does the above mean? Where does it flood with coolant?

Lawrence Coppari · 10-17-2002, 08:58 AM

To get the water pump off you have to get the rear cover off from the timing belt housing because pump is behind it. You'll need a flywheel lock and a cheater bar to get nut off crank pulley. Replace the timing and balance shaft belts while your in there. If you have leaking balance shaft seals, you could do them too. I've never done those seals but they differ so put the correct one where it is supposed to go. They differ by 1mm so you can't see it. Pump is not hard to do. Did mine. I used a rebuilt water pump and it has worked out well.

Cebu · 10-17-2002, 12:49 PM

My initial inclination is a stuck Thermostat, thus no coolant flow through the radiator. This is also indicated by blowback through the coolant reservoir due to enginge heatsoak after engine shutdown.

Silverbullet951 · 10-17-2002, 01:04 PM

lawence, I was just saying if that were the situaton. If the situation was that I blew the HG, then when I would turn the car off, it would flood the cylinder wouldn't it? If that's the case, then It wouldn't start. My car started up right away. I hope it's not the HG. I think it's something minor, maybe the thermostat or the water pump. I'll let you guys know. Thanks for the replies.

951carter · 10-17-2002, 01:55 PM

Have you checked to make sure your fans are coming on?

Silverbullet951 · 10-17-2002, 02:56 PM

that's when I started to notice something. the fans were coming on every minute or so. It was a cold day.

Lawrence Coppari · 10-18-2002, 02:29 AM

Ahhhhhhhhh, Sooooooooooooo...I no understanda da ingles too good.

Silverbullet951 · 10-19-2002, 07:22 AM

i'm going to use process of elimination. I'm going to try and flush out the coolant system. How can flush it so every drop is out? Any suggestions? Thanks.

ae1969 · 10-19-2002, 07:54 AM

Silver...... the thing that alarms me the most is the whirring sound..... If it is a thermostat/waterpump combo it would cause all the symptoms that you explain. (also the broken belt scenario as Britwrench explained!)... so identify the whirring a.s.a.p.

As you know the longer you run in an overheated situation the more you compromise your headgasket and eventually it will fail, assuming it hasn't already?

Britwrench: so you have too replace the coolant sensor after an overheated situation....uhmmmm makes sense, I love this board you learn something new everyday! I will file that info.