Hey guys.

Today I was giving some guy a jump, I revved my engine to about 2500 rpms for about 1 minutes, I did this about 3 times in a 10 minute time span (engine was on for a good 20 minute), I noticed my car started to over heat after the 3rd rev, the thermometer was at the red line and I heard bubbling coming from the engine. At first I thought it was because there wasn't any cool air coming in due to me not driving it and just revving it, then I remembered that the fans come on at a certain temperature. Does this seem normal to you? I don't have any problems while driving, the most I've seen it get to is about half way up the dial on the thermometer while driving. If any of you guys should shed some insight on what the problem is, I'd appreciate it. Again, I didn't have any problems after I let the engine cool down and when I drove it home after I jumped him. Thanks a bunch guys.

*UPDATE* I just went outside and I saw that my car has one big fan, I turned on the AC and the fan came on. So that eliminates the fan. Could it be the thermostat or a sensor that caused that? Or could my radiator need flushed with only 98,000 miles?


Chris

1991 Camaro RS 305 TBI

 

Well, the fan turns on two ways, one is when you have the A/C on and the other is through a fan switch in the engine block. The fan switch on the block could be bad is what I am guessing.
Was the fan even on when it overheated when you were jumping the other car?

On your car, the swtich is on the top of the intake manifold right near the thrermostat housing. It's about $12 at a parts store, tell them that you need a Coolant Temperature Sensor.
My friend had the same problem on his 91 L03 Firebird, his sensor had a broken connector and would fall off so I gave him one of my spare ones.

 

I had a bad fan switch in my 91 rs camaro. I was having the same exact probs as you. the guys here helped me out. (thanks again guys!!!)
My solution was to get a new fan switch, $11@autozone. While I was driving it around before I replaced the fan switch, I was real careful to monitor the engine temp. Every time it even got near hot, I switched on the a/c, which turned on the fan, and cools the engine down. Good Luck!

 

I BELIEVE THE FAN SWITCH IS LOCATED IN THE HEAD BETWEEN #6 &8 CYLINDERS. THE TEMP. COOLANT SENSOR IN THE INTAKE MANIFOLD FEEDS TEMP. INFO TO THE COMPUTER.
IF YOU ARE USING HEADERS, LOOK TO SEE IF THE WIRE FOR THE FAN SWITCH HASN'T CONTACTED THE HEADER AND BURNED.
JIM

 

Are you sure because on my friends 91 LO3 it was on top of the intake manifold. You might be thinking of the sensor for the temp gauge which should be a different sensor.

 

the fan switch is on the passenger side, in the block.

 

The temp sensor for the gauge is on the driver's side of the block.

 

So is it easier to get to the switch from the bottom or top of the block? I can see it but it seems hard from both ways. I already have my new switch just need to know what's easier.

Chris

 

The temp sensor for the fan is in the rear of the pass side head.
Before you go pulling out the temp sensor make sure everthing with the wiring is ok. All you have to do is ground the wire out with the ignition on and the fan should come on. I don't think its the relay b/c it comes on with the ac. If it doesn't come on when you ground out the wire you have a problem somewhere else.

 

GOOD ADVISE FROM THATS ME.
REMOVING FROM THE TOP IS BEST UNLESS YOU HAVE DRAINED SOME OF THE COOLANT.
REMOVING FROM THE TOP IS ALMOST IMPOSSIBLE IF YOU HAVE HEADERS.
JIMJOHN