Cooling System Pressure Rescue How to Fix a Radiator Cap That's Leaking Pressure

If the system will not hold vaccum then you have a internal seal problem (Headgasket failure). ... The cooling system can still hold pressure. But ... With everything going on in the world what is the problem? It's an OPEN cooling system. It's going to suck and pull must I put up a pic of " ... However, it's sometimes caused by a damaged radiator hose that causes a vacuum effect. Don't drive with a leaking radiator cap, even when your ... The cap is designed that the excess pressure from the radiator is supposed to be bled into the overflow tank. I read some people use tire pressure valves inserted into old radiator cap and pumped them up with a bicycle tire pump with a pressure meter or ... SRPWR wrote: Inside the filler neck on the rad. There is a lip about 3/4 inch down that the rubber O ring on the rad cap sits on. My car would ... That having been said...just keep the tank full enough to make up for the stem that WILL escape, and do a test when you get the cap to determine ... Make sure the face where the gasket goes is smooth(mite need to light sandngi)Then I'd use a pressure test cap and get it up to pressure,then ... > replace the cap. ... > leaking. Wonder if I should replace the cap. Rad caps get old and REFUSE to hold pressure, which will cause boiling. I had the same problem as you described.Found that the distance from cap to the sealing rubber ( at end of cap ) wasn't as long as it should ...