How to fix overheating issues on a 1986 Pontiac Fiero 2M4?

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May 14, 2025 at 6:54 pm #1408 Reply
Daevin
I have just got my hands on a 1986 Pontiac Fiero 2M4, it’s definitely a project car, and I’m not sure where to start on it. The car starts runs and drives, but the radiator fan isn’t spinning, there seems to be oil on top of the engine, the serpentine belt needs replaced, and the engine temperature gauge doesn’t work. If any of you could help me with advice to get this car running without risk of blowing up the engine from overheating.
May 14, 2025 at 6:55 pm #1409 Reply
James
Change temp gauge sensor first, then get fan working. You can power the fan straight off the battery just to find out if it works and will keep the engine from overheating, change the belt and have at least a 5lb ABC fire extinguisher handy, clean as much as that oil off the engine as you can.

Make sure the fluids are topped off and air cleaner is clear and then Fire It Up, watch your gauges. Good luck
May 14, 2025 at 6:55 pm #1410 Reply
James
Focus on getting the engine running firs.
May 14, 2025 at 6:56 pm #1411 Reply
Besticanafford
Oil on top of the engine, replace oil fill cap gasket. Wicked cheap. Might just replace the valve cover gasket while you’re at it. If it’s like a modern one at all, it might be filling your spark plug holes with oil, and leaking on the outside.

The cooling fan should only run if it’s too hot for the thermostat to keep the engine cool.

If it just never runs, in that, it could be anything. Coolant temp sensor (does the gauge move?), relay, or wiring, OR the fan itself.
May 14, 2025 at 6:56 pm #1412 Reply
Demonoid
Burn box those things overheat and catch fire, good luck! Put in a engine that doesn’t leak oil like a Chevy lol, and it should be OK.
May 14, 2025 at 6:56 pm #1413 Reply
John
Just make sure you keep a fire extinguisher handy at all times, those things burn into the ground.
May 14, 2025 at 6:57 pm #1414 Reply
Dion
Work the problem in order. Radiator fan first. Then see if it overheats using a thermometer. If it does, pull the thermostat and see if that gets it under control. Replace thermostat if needed.

If it runs hot without a thermostat, you may have a clogged radiator that needs boiling out or replacement.

Once you get it to where it doesn’t overheat on the thermometer, put the thermostat back in and watch while it runs for a while. It should come up to temp stamped on the thermostat and then level off.

Then put in a new coolant sensor, put the radiator cap on and rerun the coming up to temp and leveling off test using the dash gauge.

Next is serpentine belt. No real trick to that as long as it’s routed correctly.

Finally, clean the top of the engine and try to suss out where the oil’s coming from. Probably just a valve cover gasket, or maybe a bad oil fill cap or leaky PCV grommet.

Have fun with your new baby.
May 14, 2025 at 6:58 pm #1415 Reply
Cj Serv
You’d be as well buying ripped clothes, holes in them, then going to a Taylor’s saying I can’t sew, but how do I fix this.
May 14, 2025 at 6:58 pm #1416 Reply
Reed
1st car I ever went through check the fuses, check wiring for mouse bite, do a complete service on the motor and tranny (including PCV valve, but a new slave cylinder (if equipped). Or pull that bullshit out and put a 3.8 n it
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How to fix overheating issues on a 1986 Pontiac Fiero 2M4?

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