Well some guy put a aftermarket radiator in my car. 91 v8 anyway get to te point. there was a 13ib cap and the rubber was all dry rotted and cracking.

Would that cause the car to run at 240 degrees all the time. resivoir tank fills fine also replace thermostat to 180 stock recommended stat also new resivoir bottle. Old one full of soute. Also flushed twice haven't had it running long enough to see if the car will get up to a high temp with the new 16ib cap and thermostat and flush.

Tell me if you think this fixed my problem at least for now if you might know.

Thanks.

 

The cap shouldn't cause the car to run hotter (unless its actually leaking/letting steam out), it just keeps the system from boiling until it gets to about 250 degrees or so( increased pressure = increased boiling point). Make sure your water pump is circulating and there is no air in the system.