'87 Brat with SPFI. Over the weekend, I went up into the mountains. The temp gauge went up to the red while climbing the mountain, and while creeping along a 4x4 trail. If I turned the heater on full blast, I could cool the engine down a bit, and get it out of the red.

 

So the question is: are my gauges a bit off due to a bad ground, is the water pump not pumping enough, or is the radiator not cooling enough? Water level was high enough, and no evidence of any leaks at the moment.

Its really hard to tell without my crystal ball, but I'd start with the basics.

 

Check that your coolant is not too old and needing replacement, just because it looks good doesn't mean its providing the boil-over protection you need.

 

Radiator caps that don't hold the 16psi or so pressure that they once did can cause overheating

 

Leaves, dirt and dust in your fins, fins pushed over or debris caught between the condenser and radiator.

 

Thermostat not operating correctly, it's a cheap fix. Don't be tempted to replace it with a lower temp unit, it will cause more issues than it might fix.

 

Water pumps do go bad, but the impeller is metal, so its not as likely as some other vehicles that have plastic impellers.

Its really hard to tell without my crystal ball, but I'd start with the basics.

 

Check that your coolant is not too old and needing replacement, just because it looks good doesn't mean its providing the boil-over protection you need.

 

Radiator caps that don't hold the 16psi or so pressure that they once did can cause overheating

 

Leaves, dirt and dust in your fins, fins pushed over or debris caught between the condenser and radiator.

 

Thermostat not operating correctly, it's a cheap fix. Don't be tempted to replace it with a lower temp unit, it will cause more issues than it might fix.

 

Water pumps do go bad, but the impeller is metal, so its not as likely as some other vehicles that have plastic impellers.

 

Radiator cap I replaced several months ago, because the one that was there was turning to hard rubber.

 

Sounds like the water pump should probably be towards the bottom of the list right now then.

 

I'll be sure to check coolant, and radiator fins for blockage.

 

Not sure what thermostat is in there, but since they are cheap, it can't hurt to put a new one in.

 

Thanks for the suggestions.

Did you hear your radiator fan working? It would be the first thing Ide check.

Good call on the radiator fans, if those aren't spinning when it gets hot you certainly have a problem.

electric radiator fan. clutch fan. go dealer only on the thermostat.

 

also backflush your radiator and use a/c coil cleaner on the outside of it, it will remove alot of the oxidization from the outside of the radiator

Did you hear your radiator fan working? It would be the first thing Ide check.

 

I do know that the fan works, and kicks on and off. But it shouldn't be a fan issue at 50+mph up a hill.

 

electric radiator fan. clutch fan. go dealer only on the thermostat.

 

also backflush your radiator and use a/c coil cleaner on the outside of it, it will remove alot of the oxidization from the outside of the radiator

 

Never thought about oxidation on the outside of the radiator. Interesting idea there.

50mph under load... is it consuming water? even small trace amounts

 

is it boiling back into the bottle even when not "over" heated?

Personally I would start with a thermostat replacement. None of the other fixes will do you any good if the thermo is bad or failing.

I would go with a flush, thermo just because, but given the age and no other issues, it may be a clogged radiator since it only did it under load.

climbing the mountain, and while creeping along a 4x4 trail

I do know that the fan works, and kicks on and off. But it shouldn't be a fan issue at 50+mph up a hill.

Your post makes it sound like you were "creeping" up a mountain road... You didnt mention 50mph. I will mention if your car is actually running that hot your fan shouldnt be kicking on and off. It should just be on trying to get the temp down, if you come to a stop and your gauge is in the red and the fan pops on and then off, Ide question the gauge and/or the fan system.

If it heats up under load (wheeling is hard work) and at highway speeds, I would look at the Thermostate, cap and radiator.

 

Is it normal at idle?

Your post makes it sound like you were "creeping" up a mountain road... You didnt mention 50mph. I will mention if your car is actually running that hot your fan shouldnt be kicking on and off. It should just be on trying to get the temp down, if you come to a stop and your gauge is in the red and the fan pops on and then off, Ide question the gauge and/or the fan system.

 

My apologies, I meant 2 different things there. Climbing I-70 it heats up, and creeping along a 4x4 trail it heats up.

 

If it heats up under load (wheeling is hard work) and at highway speeds, I would look at the Thermostate, cap and radiator.

 

Is it normal at idle?

 

Yes, normal at idle. But normal for this car, is at or slightly above half way up the gauge. At least, that's where it's been since I got the car 18 months ago.

It sounds to me like its time to hit it with a temp gun, or drop in a mechanical temp gauge. All my EA81 GL's temp gauges have read between 1/4 and 1/3. Werent you having some issues w/gauges befor?

It sounds to me like its time to hit it with a temp gun, or drop in a mechanical temp gauge. All my EA81 GL's temp gauges have read between 1/4 and 1/3. Werent you having some issues w/gauges befor?

 

 

Yup your radiator is ancient and sounds like from here it may be clogged.