Pressure test coolant system

[wrldky]

These seems like a basic question but when you are doing a pressure test. How do you plug the overflow tube so the air/coolant doesn't escape from there?

 

[WaltNYC]

Most work by removing the cap from the coolant reservoir and attaching the air pump where the cap would be. Kits generally come with various cap sizes to accommodate multiple vehicles.

Once attached, pressurize the system to 15lbs and wait for leaks to reveal themselves.

 

[wrldky]

Yes I understand that but doesn't air escape from the overflow tube on the coolant reservoir tank?

 

[boxster]

Yes I understand that but doesn't air escape from the overflow tube on the coolant reservoir tank?

The pressure tester cap should seal below the overflow tubes.