Ok, a question... How does the coolant expansion tank cap supposed to work? I am noticing that the coolant is overflowing once in awhile. The temperature is fine, but it is just overflowing... once in awhile.

Obviously this system is not like the conventional radiator with pressurized overflow cap that releases excess fluid to the expansion tank then sent back. The expansion tank itself is pressurized.

Visual inspection of the cap seems to be fine. There doesn't seem to be any broken plastic and the o-ring inside the cap seems to be in decent shape as well.

Does anyone care to comment?

Its a fullly pressurized system only the cap is on the tank instead of the radiator. Expansion of the fluid is taken up by pressurizing the air in the reservoir. The cap will release pressure but at a mugh higher pressure than a conventional system.

So, get a new cap. Might want to get a new reservoir as well since you will need one sooner or later.

Bob

Yeah, I maybe over thinking for a $10 part... I will go pick one up.

Get the pricier sky blue cap, that is Made in Austria....not the dark blue, China-made one, which fails way too often.