A radiator cap is used to keep water or coolant inside of the radiator but it is also in place to relieve pressure if … CAUTION: Radiator pressure testing tools are very sensitive to small air leaks, which will not cause cooling system problems. I have tried three more caps and they wont seal. The cap is not sealing the top of the radiator and when the car heats up all the … Yes,a radiator cap that does not properly seal with the correct pressure rating will cause over heating and water spill out.Try a new radiator cap that is of the correct # pressure rating. went and bought a $5 radiator cap at the local autozone. Genuine Toyota (16401-20353) Radiator Cap Sub-Assembly I swiftly left to a nearby autoparts store and compared it side by side and they are exactly the same apart from the sticker label. If you have a Polar heat exchanger do not exceed a 4psi cap and if a Polar the 6PSI. Please beware of "original equipment" part for your vehicle. Or you might have a radiator that’s leaking. The radiator cap keeps your engine cool by sealing and pressurizing the coolant inside. Use Code: CELEBRATE. The radiator cap keeps your engine cool by sealing and pressurizing the coolant inside. Benefits of Radiator Stop Leak and Sealant Once the pressure reaches its maximum, the cap opens the release valve and allows heat to escape. ... should be just at the sealing lip of the cap. A bad cap can cause a slew of problems -- … Radiator caps can be found at any nearby auto parts store and are typically not very expensive. If you don't see any coolant leakage whatsoever, then there's not much else it can be other than a head gasket. I bought a used car, and the radiator cap sealing surface inside the radiator opening was chipped making it impossible for the radiator cap to seal properly making it impossible for the system to pressurize causing coolant to come out. It has nothing at all to do with squeezing air into the tank. Defective Radiator Caps. Show more answers (5) Still have questions? With the new cap the system will go to 10-15 lb at normal temp. The radiator cap seems like a very simple device that has no other use than being a stopper for a hole. Find our best fitting radiator caps for your vehicle and enjoy free next day delivery or same day pickup at a store near you! Edited May 13, 2018 by Tony Brooks And over time your fuel costs will also increase. The worst part of using this radiator leak is that you have to wait a long time, up to 20 minutes, with the engine idling to ensure that all of the cracks within the radiator or gaskets are properly sealed using the radiator sealant. The radiator cap keeps your engine cool by sealing and pressurizing the coolant inside. For that to be the case, there had to be not one, but two leaks between the cap and the radiator. *Measurments are reference only and may vary slightly with application. To do this, set the heater controls in the car to maximum heat, remove the radiator cap (or remote mounted coolant pressure cap, sometimes on the overflow tank) and fill … 20% off orders over $100* + Free Ground Shipping** Online Ship-To-Home Items Only. ... it’s important that even the smallest components are working properly. Hey Ken==The radiator cap isn't sealing. I cant see any obvious imperfections. In this case, the coolant is more likely to be lost to boiling off than by simple evaporation. If coolant is not moving effectively throughout the system and your car is overheating, have your service advisor check the radiator cap. They might not warm up or they might only get hot at the top or at the bottom. Air in the cooling system . It is designed to hold the coolant in the radiator under a predetermined amount of pressure. Also inspect for dirt or distortion that may prevent cap from sealing properly. 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