1991 Corolla second opinion



Hello, Everyone.

My 1991 corolla (170k miles) has been having overheating problem recently.

My mechanic told me it is radiator problem, and I should replace the radiator.

My symptoms are,

1. Overheating (needle keep going up and up to near red zone) after 20 min highway driving. After turning off AC, it goes down little bit. For local driving, overheating comes much sooner like after 14 min driving.

2. It seems like that coolant level’s are same always. I mean no leaking.

3. Upper radiator hose is hot (in my humble opinion, this means thermostat works fine, right?)

4. No white smoke in exhausted gas. (no gasket leaking??)

5. I changed radiator cap recently. (since I thought it could be a problem)

6. Radiator fan seems running fine, however, manytimes it does not turn on, or blowing strongly even it is way over overheating. When I turn on the AC, the radiator fan turns on.

and My mechanic did chemical flushing for radiator just in case. It looks like after the flushing, overheating comes little bit slower. Before the flushing, I could not drive more than 15min highway because of overheating.

I am thinking that either radiator or fan control thermostat or fan related things are problems. I am worring that what if replacing radiator, the problem is not solved.

Thank you very much for your help!!



[b]One way to find out if it is the radiator is to point a laser thermal gun across the surface of the radiator. This will show where plugged radiator cores are located by the lower temp reading compared to the cores that have hot coolant running thru them.

But if this is the orginal radiator, I wouldn’t be at all surprised if it required replacing. Because the symtoms you describe point in that direction.



Thank you for your answer, Yes, this is original radiator.


Wow, your radiator lasted a LOT longer than the one on my '91 Corolla. I suggest you replace the thermostat and the fan switch at the same time you install the new radiator. Why gamble on an old thermostat and switch?


Yes, I’ll change them together. Thank you.


I changed radiator today. My mechanic is right. No more overheating problem. Thank you all!!