1988 SAAB 9000 car runs hotter than normal

MARIAH70438

MEMBER
1988 SAAB 9000

Other Category problem
1988 Saab 9000 Engine Size unknown Front Wheel Drive Manual 255000 miles

my car is running hotter than normal, started by running hot while idling or in stop and go traffic in town, now runs hot, but not in the orange zone, even on highway. The fluids are fine, there is no coolant leak that I can tell. I think it may be the thermostat or the switch that tells the fan to turn on, but I don't know for sure. The fan turns on when I turn the car off, like it should, and I don't know if the fan turns on when I am driving. There has been a weird noise no mechanic can figure out when the car is heated up and been running for a while. This is almost a humming noise, gets louder at idling in stop and go traffic especially after coming off the highway. It all started by just running hotter in stop and go, now runs hot even on highway. Runs a little cooler when I turn on the heat to HIGH in car, pulling some of the engine heat into the car, and the temp gauge goes up some while going up hills. Any advice on what the weird noise is, or why the temp is running hot? I had the oil changed, last time that seemed to help with the temp, but not this time. The belts and hoses are fine, too. The heat inside the car definitly still works just fine.

5 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Was the noise there before it started running hot?

For a start you should go ahead and replace the thermostat and make sure you bleed the cooling system when done. The mechanics are they using a listening device to pin point the noise or wild guessing where it could be?

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Saturday, December 29th, 2007 AT 11:58 AM

RASMATAZ

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From: mariah70438
To: rasmataz
Posted: Sat Dec 29, 2007 12:34 pm
Subject: saab running hot
yes the noise was there before it ran hot, and the mechanics were wild guessing the noise. My boyfriend attempting to change the thermostat now, the shop wanted over $150 to do it.I have the part, cost about $12.

When he's done with the thermostat-get a short garden hose and start probing the engine and comeback and tell me where its coming from.

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Saturday, December 29th, 2007 AT 12:41 PM

MARIAH70438

MEMBER
2 POSTS

Ok. The thermostat is changed. And still running very very HOT! Now we are seeing that the fan is not kicking on, even when I turn the car off. The fan used to kick on when I turned the car off, to cool the engine. Now it's not kicking on at all, with the car on or off.I guess the problem could be a combination of things. The next thing we are going to try is the fan clutch. I checked with few saab repair sites, I will also have to change the fan assembly and the fan themostat and change the fan themostat switch to a new one that kicks on at 82 degrees instead of 92 degrees.

Well, will check these things out and let you know I guess. The cost of all these parts at Auto Zone is about $120.

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Saturday, December 29th, 2007 AT 3:44 PM

RASMATAZ

MECHANIC
75,992 POSTS

Check the water temperature switch/fan relay. I don't think you have a fan clutch -you have an electric fan am I correct.

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Saturday, December 29th, 2007 AT 4:35 PM

RASMATAZ

MECHANIC
75,992 POSTS

Inbox : Message
From: mariah70438
To: rasmataz
Posted: Sat Dec 29, 2007 7:13 pm
Subject: HOT saab
there is a wire harness that comes from the radiator, we bypassed that, and jumped the fan from the battery directly. The fan does start, so it's got to be that the switch relay is bad then? Can that be the whole trouble causing the overheating? How did it go out so suddenly? It has been getting progressively hotter by the day, but then when we changed the thermostat, it ran really hot and does not cool at all even driving 55. It heated up just about to the orange in 2 miles.

So do we just change the switch relay? And that should fix it? And where is that at?

Is that the "fan switch" that we buy that turns the fan on at 82 degrees? Is it located right on top. Near top. On left? And is it what? Shorted out? That is why we can get fan started by bypassing that?

HELP. Lol

Take the thermostat back out could be bad again-do not put it back in -run the engine without it and see what happens.

Sometimes the temperature switch is strictly use to indicate the actual temperature of the gauge and the coolant temperature sensor that computer uses its signal to activate the fan relay and than to the fan motor.

If I were you go ahead and wire the fan with a circuit that is controlled by the ignition switch-when the car is off the fan is off and vice versus.