I've been having problems with my 1973 Challenger with a 318 overheating. Its fine when it sits at idle but when I start to drive it she gets so hot that steam starts billowing out from the radiator overflow valve. There was a big steam cloud coming off of it at a stoplight it was overheating so bad. I know its not a coolant level problem because I have driven it when the coolant was low and when it was full, I flushed the radiator about 2 years ago. I just did an oil change and put enough oil in so that shouldn't be the problem either. I recently changed the temperature sensor in the radiator and that didn't do anything. There isn't any coolant leaking from the engine so its not a blown head gasket. The heater doesn't really work, the controls don't do anything and the vent is open but I don't think that would make the engine overheat that bad. The radiator itself is small, only about 19" wide by 26" tall and there is no fan shroud. Maybe it needs a new radiator or new heater core and a vent fan? Any help is much appreciated as I miss driving around my beautiful Challenger. I am going to be out of work soon so I have limited money for this problem.

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With the car running, remove the radiator cap to ensure you can the water moving, that will verify if the pump is working. You also might want to pull the thermostat and check it for proper operation. It's a simple enough test with a pot of hot water and thermometer. Also when was the last time you had the cooling system flushed?

Good luck..

 

I'm thinking radiator or thermostat. Have the radiator tested and replace the thermostat (stat), or quickly. Then go from there. Also replace with new antifreeze.

 

In my '73 Challenger, I did replace the thermostat that fixed the problem and it worked fine. What you described tells me that is what it is.

I would for sure flush the radiator. Many places will flush for you several times but you have to ask for it and make sure they do it
before they fill it back up with coolant. Otherwise, they will charge for the extra coolant. The path going to the heater tells me that possibly it has corrosion in it.

If you do those 2 things, I think you will fix both problems.

It helps to have a heater in the winter.

Best Wishes!

 

I have to agree with what everyone else is saying.

I would first change the Tstat and make sure the water pump is working

 

are you running a clutch fan? if so, is it tight?

 

I didn't even think about the fan, that's something to consider as well. Do you have a fan shroud?

 

All of the posts here might be correct if the problem has always been there.

If this is a new problem, you have a pin hole blown head gasket.

Everything is great at idle because there's no pressure. Once you get going, it opens up and the pressure goes back to the radiator because the leak is on the inflow side of the engine.

Don't dispair yet. Bars Leak makes a new head gasket repair in a silver bottle for about $10. You'll need two bottles for this treatment. Follow the direction precisely,

NO SHORTCUTS!

You can thank me later. Let's just get you back on the road!

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