Over Heating
Thread Starter
Cruising
Joined: Jun 2009
Posts: 10
Likes: 0
Over Heating
Have 1986 that over heats. Have installed new thermostat, run cleaner thru radiator, cleaned radiator fins. Rear fan works, front fan dos not work. Car is not being driven, setting idling. What may be my problem? Thank you.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
What do you mean, "overheat"? It is normal while idling for your coolant temp to be above the opening temp of your thermostat and the OEM stat is 195 F. The main fan comes on at 228F and goes off at 211 F and if you let your 86 idle, the coolant temp will cycle between about 228 and 211. The aux fan comes on at 238 F and it will not come on if you let your 86 idle for long periods. This is not, "overheating", this is normal and you need to get used to it, these temps will harm absolutely nothing in the engine. GM says if the coolant gets to 260F, turn the engine off and let it cool down. Got it! 
Racer
Joined: Dec 2004
Posts: 289
Likes: 3
From: new york
What do you mean, "overheat"? It is normal while idling for your coolant temp to be above the opening temp of your thermostat and the OEM stat is 195 F. The main fan comes on at 228F and goes off at 211 F and if you let your 86 idle, the coolant temp will cycle between about 228 and 211. The aux fan comes on at 238 F and it will not come on if you let your 86 idle for long periods. This is not, "overheating", this is normal and you need to get used to it, these temps will harm absolutely nothing in the engine. GM says if the coolant gets to 260F, turn the engine off and let it cool down. Got it!
Amazing the exact info I needed my 89 gets hot, my fan doesn't go on. If I cant figure out why I am going to wire it off battery w/ toggle switch. Now I know when to turn it off an on.
Burning Brakes
Joined: Oct 2000
Posts: 863
Likes: 0
From: Portsmouth,Va USA
Turn on the A/C and check it..
Stay safe
Rick
Burning Brakes
Joined: Dec 2007
Posts: 805
Likes: 3
From: Waco TX
The one thing that made a HUGE difference for me was having the radiator cleaned. And I mean taking it out of the car and running a powerwasher through the fins to get all the grass/debris that has collected over the 20+ years.
Also, take it to a radiator shop and have them pop one of the side tanks off and run a bar through each tube. This made a HUGE difference with my 94. Half the horizontal tubes in my radiator were clogged with mud. Even running a "cleaner" through the system isn't going to make that stuff go away.
Hell, it usually doesn't even get to 200 anymore unless I am autocrossing or idling for a LONG time.
Also, take it to a radiator shop and have them pop one of the side tanks off and run a bar through each tube. This made a HUGE difference with my 94. Half the horizontal tubes in my radiator were clogged with mud. Even running a "cleaner" through the system isn't going to make that stuff go away.
Hell, it usually doesn't even get to 200 anymore unless I am autocrossing or idling for a LONG time.
