Rich_Jenkins

Thanks to the OP. I remembered to check my water level today, so I had the cap off this morning early. Mine was hand tight, and fairly easy to open. Definitely a ‘click’ at the end before it lines up.

i looked at the underside and there was some residue on the contact areas of the thread landings, but not much.

GT3FZS

Well....no luck!
Tried channel locks, vise grips, gloves, still so tight I cannot get past the first 5 degrees of CCW turn.
I am concerned about damaging the cap, and subsequently not maintaining pressure in the cooling system. My nearest dealer is 110 miles away, and no service is needed at this time, so that is the last resort.
Any other thoughts? Heat? Other?
Thanks.

LexVan

Just leave it till your next planned service. Your car does not need any coolant adjustments after winter hibernation. It has a TON of coolant in it.

Rich_Jenkins

I kinda agree with @LexVan , if you can make it the dealer's problem.

If not, and you absolutely need to remove it, I would be tempted to boil a couple cups of water, make a dam out of some MF towels around the cap and sides, then pour the hot water onto the cap, trying to heat it up slightly. You might get it hot enough to expand just enough you can coax it off with some proper leverage.

barncobob

might be crossthreaded,,thats a problem, maybe cut it off with dremel

Carl Over

Leave the car in the sun for many hours after being car out of garage. There will be no issue with temp in the coolant system. Keep trying. It will come loose. Immediately put silicone lube on all threads. That will solve the problem.

BSO

I’m going to suggest the opposite of heat, which causes material to expand.

Ice cubes in a zip lock bag with some water. Put the bag on the cap after the car has been sitting over night with the rear lid open.

Make sure that the cap contacts the cold bag surface and the cold liquid inside as much as possible. Try to open when the cap feels cold, you could also dump the cold liquid from the bag on the cap as well before trying.

Or just pile up a mound of ice over the cap and let that melt, then try. Use a towel to ring the mound of ice and keep it place.

Good luck.

Jack F

What orientation is the raised section of the coolant cap? Between 9 and 3 o’clock? When it get stuck , this is barely above three o’clock? You can try a rubber strap wrench. I used to heel of my both hands to twist the cap off. Then applied silicone on the threads and it’s an easy one handed turn each time. If you can’t get it off, take it to your dealer. They will want to let it cool down until coolant is below 140F so plan on waiting a while or drop of the might before.

CSK 911 C4S

Huh?

barncobob

when all else fails.....CHEATER BAR TIME

Jack F

I too am not sure why you would want to cool something since this would get it tighter. Maybe it’s some kind of thermal shock deal.

BSO

My answer to those asking about cold effects.

Materials contract with cold, heat expands them. An exception is water, which expands when freezing, hence broken water lines during a cold snap.

The tolerances between two surfaces would tend to increase from each other when they contract.

"When a material is heated, the kinetic energy of that material increases and it's atoms and molecules move about more. This means that each atom will take up more space due to it's movement so the material will expand. When it is cold the kinetic energy decreases, so the atoms take up less space and the material contracts."
http://www4.hcmut.edu.vn/~huynhqlinh...t/ae40.cfm.htm

Carl Over

Water does expand when frozen. The plastic cap will shrink when cooled. Are you saying that your proposed method will get water in between the coolant cap threads and the bottle neck and somehow expands it?

Seems to me that cooling the cap would result in it being tighter?

BSO

I'm saying nothing other than cold will affect materials by making them contract.

What happens when two materials are in close contact with each other, such as the male threads of the cap and the female threads of the reservoir throat, are exposed to cold?

They aren't glued together, otherwise they would not come apart. Friction between the two thread surfaces holds the cap on (as well as the click lock) and creates an air tight seal.

Disregard your inference regarding water, that has nothing to do with what I've written or said; it's the action of cooling down the surfaces that causes the materials to contract, as they contract, the friction force acting on the threads is reduced, THE THREAD SURFACES ARE PULLED APART, and the friction force is reduced. Reduced friction also reduces the amount of force required to screw or unscrew the cap.

Don't believe me? Go ask someone who teaches Physics 101.

One last note, mechanics freeze bearings to shrink them, allowing easier installation. Does that sound like expansion?

subwoofer

Rubber monkey wrench. And once the cap is off and not cracked, re-install not too tightly and open peridically to figure out if the coolant level is fine with the weird thingy floating between the min amd max marks.