GenVibe - Community for Pontiac Vibe Enthusiasts

A friend dropped off his 2004 Vibe saying it is leaking coolant. Level was down so I filled it up with coolant and ran it up to temperature. No evidence of leakage. The radiator cap seal did look suspect but not so much after I cleaned the crud from it. Left it running and lifted it up to inspect underneath, still no sign of coolant leakage anywhere. Weird thing is when I shut it off, I loosened the radiator cap to see if pressure was present and there was zero pressure. I pressure tested the system with a pump up tester and it seems to hold for quite awhile. The coolant looks really murky but I don't want to replace it until I am certain it is not leaking. The oil looks good on the dipstick, no milky color. Any suggestions as to where I might look further? Thanks!

Did you have the adapter to test the cap with the pressure tester? Did you try running the engine with the pressure gauge attached? That could show head gasket problems.

If there was crud on the cap, it's probably bad. A leak from there might be vapor, not visible in the short term. That's all I can think of to explain the symptoms as written. It's an inexpensive part.

welcome to genvibe.

Hopefully its the cap, but maybe pull the plugs to look for coolant fouling. When you left it running, did you notice any extra steam in the exhaust?