Seized Coolant/Overflow tank Cap

[Felix_29]

Hi everybody,

The cap on my S.S. overflow tank in the engine bay is seized up. I can turn it counterclockwise to the left about a turn but it will not lift off. Does anyone have any advice on what I can do to get it off? Shouldn't it work like any other radiator cap? Its only about three years old.

[Jonathan]

If it's like the SS tank and cap combo I have, you have to press on it a lot more than you might think to get it to come off.

I think it's the tolerances that were not quite right and you need to get the underside lip of the cap to come free of the rim around the bottle. There are cut outs in the SS rim (like notches) that let you take it off, but it seems you really need to press hard to get it to turn the extra 1/4 turn or so (counterclockwise) to get it off.

If you're unsure of how much force to use, try loosening with your right hand while you hold the underside of the SS reservoir with your left so it doesn't feel so much like you're going to push the damn thing down so far that it snaps it off the brackets. Do it with a cold bottle maybe if you're trying this for the first time so you don't burn yourself.

It will come off, it's just a matter of knowing where that point is. Once you get it off, inspect it to get familiar with what you're dealing with (or take a couple photos) and then put it on and off a couple times to practice/remind yourself for next time.

IMO, it's the neck of the SS bottle that's not quite the right shape more so than the cap or spring on the underside of it.

[DMCMW Dave]

Press hard down as you unscrew it. Like a safety medicine bottle cap.

[SS Spoiler]

Maybe some filing on underside of the lip is needed?

[DavidProehl]

I've also seen the caps get snagged on the hose clamp near the cap if the clamp isn't positioned properly.