will a tear in the seal of a radiator cap cause the car to overheat ? it's not drawing fluid out of the reservoir,also
If there's no steam or coolant coming out from it than it should, but it will eventually go out so your best bet would be to buy a new cap, there a pretty cheap part ranging anywhere from 6-30 dollars and very worth it in the long run
if there is an air leak thru the cap seal, would it keep the radiator from being able to siphen from the reservoir ? There are no leaks around the water pump and the oil is clear but it will overheat and blow out of the overflow hose.
What that small reservoir is called is the overflow reservoir and all that is there for is when there is to much coolant in the radiator the pressure forces the excess coolant into that reservoir instead of on to the ground. The cooling system becomes pressurized when up to temperature and doesn't create a vacuum. Sometimes it will suck up some of the coolant in the overflow but not much only while it's cold witch is long when your driving it. So you'll want to replace the radiator cap.
Short answer - YES. Replace it.
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