98 SC2 overheat problem-help

[JMan74]

I have 98 SC2 with 117K miles. Recently I have been experiencing overheat problems and am looking for some advice on the best way to check out the system. should I check the sensor first or the radiator cap? or the fan motor? Today when I ran it for about 10 miles around town it quickly got over 3/4 approaching red, and when I opened up the hood and the fan wasn't on. I would think it would be on at 3/4 or even 1/2. never had an overheat, this cars always, always runs on the dot of 1/4 for the life of the car. Coolant was changed last at 90K. In the 98 is the fan tied to the A/C? I don't think so but don't know for sure. Any help would be appreciated.

 

[Kirk Kohnen]

Start car, turn on A/C.

If the radiator fan doesn't turn on, suspect the radiator fan motor.

They're sealed motors, but they have brushes in them. Those brushes wear out. When they do, you get the symptoms that you describe.

Given the 117K miles, your radiator fan is probably worn out. It's a pretty easy job to replace it.

 

[JMan74]

Kirk,

Thanks. That's where I will start tomorrow. Kragen's stock them. should be a quick fix look at the manual. Any pointers from anyone that has changed it already? Things to look out for? Looks simple enough though.

 

[Alex Marcuzzi]

I just had an overheating problem on my 93 swi and it turned out to be the coolant temperature sensor. On my car I could not do the fan test with the A/C because it is not working, so even if you turn the A/C on the fan did not work. You can do another quick test to check the fan operation by shorting out the coolant temp sensor. On my SW1 there are two sensors. One drives the temperature gauge and the other tell the computer the temperature of the coolant. The one that drives the temp gauge has one wire and the one that goes to the PCM has two wires. All you have to do is unplug the connector of the one with two wires and take a very small paper clip or staple and connected across the two pins on the plug and then turn the motor on and the fan should turn on. If it does not turn on it is either the motor or the relay which turn the motor on. If you have a meter you can go to the fan motor plug and measure if you have 12V.
Alex

 

[James1549]

They're sealed motors, but they have brushes in them. Those brushes wear

out. When they do, you get the symptoms that you describe.

First you should check to see if 12volts are present at the fan motor to properly diagnose the problem. Anyone can throw parts at a problem, especially when it isn't your money.

Before starting the car, unplug the fan motor. Have a mult-meter or 12v test light ready. Start car and turn on A/C. Check for voltage at harness plug. If present, plug fan back in. If fan does not run, then replace motor.

If no voltage present at either wire, then you need to diagnose a bit deeper.

James

 

[JMan74]

James,

thanks. I didn't think about testing the connector first for voltage.
Duh.

I'll do that first.

Jason

 

[Kirk Kohnen]

First you should check to see if 12volts are present at the fan motor to properly diagnose the problem. Anyone can throw parts at a problem, especially when it isn't your money.

Before starting the car, unplug the fan motor. Have a mult-meter or 12v test light ready. Start car and turn on A/C. Check for voltage at harness plug. If present, plug fan back in. If fan does not run, then replace motor.

Even if it does run, you might need to replace the fan motor. At the end of the brush life, the motors become intermittent - they can start working if they're bumped or jiggled.

But, it's a good idea to confirm that you're getting 12 volts to the connector.