WindsorRon Posted August 17, 2014 Share Posted August 17, 2014 I have a 7lb pressure cap on my radiator. It was suggested that I replace it with a 3lb cap. I cannot find any reference in my shop manual or "Parts List." What would be the correct one? Link to comment Share on other sites More sharing options...
Rusty_OToole Posted August 17, 2014 Share Posted August 17, 2014 In 1949 they did not use a pressure cap. Just a plain cap, not sealed. This must have been about the last year for an unpressurized system. Link to comment Share on other sites More sharing options...
WindsorRon Posted August 19, 2014 Author Share Posted August 19, 2014 Help me understand the impact of using a 7lb cap. My car does heat up driving up hill on hot days. Would I be better off using a different cap if I can find one? Link to comment Share on other sites More sharing options...
hwellens Posted August 19, 2014 Share Posted August 19, 2014 A higher than designed pressure cap will increase the boiling temperature of the water and add extra pressure on the radiator core. I doubt it will make the engine run cooler and you have a chance of blowing out the radiator core. Link to comment Share on other sites More sharing options...
Rusty_OToole Posted August 19, 2014 Share Posted August 19, 2014 Heat up or boil over? If it doesn't boil over a pressure cap won't help.It sounds like you need to flush your cooling system. Suggest you drain the antifreeze, fill with water and a bottle of CLR. Drive around for a while (50 - 100 miles) and drain when hot. See how muddy it looks, if real bad repeat.You can also blow out the rad from behind with an air hose to clean out dirt and bugs. And/or vacuum from the front if you can get at it. Link to comment Share on other sites More sharing options...
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