Since I owned this 1968 Olds 98 convt for the last 3 weeks, I have had heating issues. The lower hose was replaced. Next was the thermostat (180 degree) and the coolant sensor. When the car is hot and standing at a traffic light (3+ mins) the hot engine light comes on. The mechanic wants to replace the radiator. He has proposed an aluminium radiator (4 rows) without electric fans. Is this the right approach?

 

How is the temperature when cruising? The conventional wisdom says heating at idle but OK at speed is an air flow issue.

 

Have you (or the mechanic) tried a good backflush of the block (including pulling the block drain plugs) and chemical cleaning/boil-out of the radiator? Also, since it is only a problem when the car is not moving, I would pull the radiator and make sure the fins are not clogged with 50+ years of crud and preventing sufficient airflow when relying on the fan only. If it has AC, check the condenser for clogged fins as well. As Fun 71 notes, it sounds like an airflow issue. Seems a little drastic to recommend a new radiator as the first option before it has been determined with some certainty that it is truly the root cause of the problem. Proper diagnosis of a problem is the key to repair success. Throwing parts at a car can get expensive and frustrating.

Dave

 

I would first see what the temperature is and not rely on the idiot light. I agree with the others you may have an airflow problem through the radiator. Are you running a clutch fan and shroud?

 

Install a known good temp gauge, even if only temporarily. These cars didn't overheat when new, so an aftermarket radiator shouldn't be required now. Be sure the sending unit isn't the problem Also, understand that your car was designed for straight gasoline. E10 will cause the engine to run lean, which causes overheating. Also be sure that your vacuum advance is working properly, including any TVS that controls it. Be sure all vacuum hoses are connected correctly. Be sure your fan clutch is working properly.