Help me diagnose my problem, please

[ricks77eb]

OK the other day I had checked the radiator and my level was OK, then I drove my Bronco to work and back and when I got home I noticed some coolant leaking. Opened the hood and found my overflow tank totally full and leaking out the top. Opened the radiator cap the next day and found the radiator way low on coolant???

What would cause this to happen??

Rick

 

[Skuzzlebutt]

Most likely, your radiator cap is warn out and needs replacing. You could be overheating do to any number of other problem, but replace the cap first.

 

[Socal Tom]

If the cap wasn't sealed properly then that can happen. What happens is when the coolant gets hot the coolant swells and fills the overflow, then when the tank cools it creates a vacuum and sucks the fluid back in. If the cap doesn't seal right, the fluid can still get pushed to the bottle, but the vacuum will leak out and it won't pull it back. You may not have seated the cap properly when you checked it the first time. or if you checked it warm, you might have let the vaccum out and got the cycle screwedup.
Tom

 

[TJK74]

I agree sounds most likely to be a fault cap.