Radiator Cap
 

I know that if you have an old and worn radiator cap it can release pressure too soon or easily and allow coolant to flood into the expansion tank and lead to overheating.

But what if the cap is too strong or stiff and won't allow pressure to escape if it gets too high?

Could this also cause overheating? :dunno:

The only time I have seen a cap not open and what it did the system blew a hose because of to much pressure. If you put a cap on there with a little higher tension then it will run a little hotter but once it opens then it go to the over flow tank. The hight the rating on the cap means it lets the system build up more pressure which allows the coolant to get to a higher temp before boiling.

If the cap is messed up, would there be any leaking coming from the cap? Or would it simply cause coolant to run over the overflow tank?

It would constantly run into the tank and fill it up because the fluid in the radiator would not get to the proper pressure and it would start to boil.

Maybe I should try that..... The guy at my shop said it wasn't a blown head gasket, but because it was overflowing he wanted to replace it anyway. I think i'll try the $7 radiator cap....

Also, check all your hoses.

Run the engine till it's nice and hot and then switch off and listen carefully under the hood for any hissing sounds.

It only takes one small split or crack and wallop, that the system depressurised!