'99 Pontiac Sunfire 4

It's cracked. GW

I have had bad radiator caps. Radiator Cap "O" ring swells, jumps out of the groove and leaks from tank overflow tube. Or, replacement cap "O" ring is too small and leaks. If weather is cool system will not leak until engine is run hard (highway, hills, stop and go) then coolant boils out because it is not pressurized.

Replace with a "STANT" brand cap. Other after market caps have a slightly smaller "O" ring and do not seal properly. Measured several brands and STANT is the only one that matches OEM part.

Larry

Geoff Welsh wrote:

I had the radiator hose on mine rub against the battery tray and split open, sucked all the coolant out of the system and the surge tank and blew it all over the freeway in california while I was on vacation, ahh that was a fun christmas...