All of a sudden - overheating issue
08-05-2015, 05:35 PM
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Car: 1985 IROC-Z
Engine: 383
Transmission: 700R4
Axle/Gears: 3.73
All of a sudden - overheating issue
Hello all,
My car is a 1985 Camaro IROC-Z. I replaced the engine with a 383 SBC, and have the ECM out of a 1990. Everything on the engine is brand new - new waterpump, new thermostat, etc. By new, I mean 3 years old but only 500 miles on it.
I've been driving the car for about 2 years and during that time, the temp gauge never gets above 180. I drove it a bit last Friday, no issue. On Saturday, I took the car out and didn't notice anything until I got home and pulled in my driveway. I got out to do a quick clean up before heading back out (I left the car running), and I noticed the gauge was at 220 and climbing quickly. I popped the hood and found that the fan wasn't running.
After pulling the car in the garage and shutting if off, I did a quick inspection and found a very loose ground wire near the battery. I fixed it, made sure it was good and started the car - the fan kicked on and everything seemed okay.
Today, I just took the car for another long ride. About 20 minutes in, I noticed that the temp jumped from the normal 170 - 180 to near 190. As long as I was moving, it went back down to 180 so I thought it was okay. As soon as I pulled into my garage, though, the temp started jumping up over 220 again. Once again, I popped the hood and the fan isn't moving. I quadruple checked the previously fixed ground wire, no issues. Apparently, it was a coincidence. Some other details:
* The car still has a fully intact air dam.
* The fan spins freely by hand, but does make a little bit of a "grinding" noise, like the bearing is starting to go bad.
* I don't have the fan switch in the passenger side head as many on here do; the only sensors I have are in the driver side head (for the gauge) and right near the thermostat; I believe this feeds the ECM.
* The car does not have A/C or controls for A/C, so I can't test the fan that way.
I'm not sure what to do or how to test. I guess I could jump out the fan somehow to see if it works? If it does, then drive the car, let it get hot and then check again - maybe the fan is getting hot and not working? What else?
My car is a 1985 Camaro IROC-Z. I replaced the engine with a 383 SBC, and have the ECM out of a 1990. Everything on the engine is brand new - new waterpump, new thermostat, etc. By new, I mean 3 years old but only 500 miles on it.
I've been driving the car for about 2 years and during that time, the temp gauge never gets above 180. I drove it a bit last Friday, no issue. On Saturday, I took the car out and didn't notice anything until I got home and pulled in my driveway. I got out to do a quick clean up before heading back out (I left the car running), and I noticed the gauge was at 220 and climbing quickly. I popped the hood and found that the fan wasn't running.
After pulling the car in the garage and shutting if off, I did a quick inspection and found a very loose ground wire near the battery. I fixed it, made sure it was good and started the car - the fan kicked on and everything seemed okay.
Today, I just took the car for another long ride. About 20 minutes in, I noticed that the temp jumped from the normal 170 - 180 to near 190. As long as I was moving, it went back down to 180 so I thought it was okay. As soon as I pulled into my garage, though, the temp started jumping up over 220 again. Once again, I popped the hood and the fan isn't moving. I quadruple checked the previously fixed ground wire, no issues. Apparently, it was a coincidence. Some other details:
* The car still has a fully intact air dam.
* The fan spins freely by hand, but does make a little bit of a "grinding" noise, like the bearing is starting to go bad.
* I don't have the fan switch in the passenger side head as many on here do; the only sensors I have are in the driver side head (for the gauge) and right near the thermostat; I believe this feeds the ECM.
* The car does not have A/C or controls for A/C, so I can't test the fan that way.
I'm not sure what to do or how to test. I guess I could jump out the fan somehow to see if it works? If it does, then drive the car, let it get hot and then check again - maybe the fan is getting hot and not working? What else?
08-09-2015, 11:50 AM
#2
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Thread Starter
Join Date: Jul 2011
Location: Augusta Township, MI
Posts: 450
Received 0 Likes
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Car: 1985 IROC-Z
Engine: 383
Transmission: 700R4
Axle/Gears: 3.73
Re: All of a sudden - overheating issue
Found and fixed.
I used my brother's bypass relay to start the fan; sometimes it was going full speed and others it was barely moving/not moving at all. Put a voltage tester on it, moving the wires was causing the voltage to jump up and down. I thought it was a loose connection, but as I traced it I found that the fuse for the fan had melted - most likely due to voltage surges caused by the bad ground - and was barely intact. I replaced the fuse, made sure no other bad connections and everything is working as it should.
I used my brother's bypass relay to start the fan; sometimes it was going full speed and others it was barely moving/not moving at all. Put a voltage tester on it, moving the wires was causing the voltage to jump up and down. I thought it was a loose connection, but as I traced it I found that the fuse for the fan had melted - most likely due to voltage surges caused by the bad ground - and was barely intact. I replaced the fuse, made sure no other bad connections and everything is working as it should.
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