Many of these pumps can generate more than 30 PSI of pressure. On all light-duty applications, you never want to exceed the pressure printed or stamped onto the radiator cap.
This pressure is the upper threshold the cooling system will EVER experience. Why? The cap’s calibrated spring and plunger will relieve pressure once it reaches the max pressure printed on the cap. This can range from 17 to 22 PSI. Pumping up the cooling system beyond its maximum pressure can create leaks where there weren’t any in the first place. This video is sponsored by MAHLE.