Valve caps won't come off!

Most probable cause is what is termed: 'Dissimilar metal corrosion'. Try spraying WD40 around the base of the caps and leaving it for a couple of days and trying again.

Kev

Molegrips. What has caused them to get stuck like this is corrosion. You should apply a slight smearing of copperslip or grease to the threads before popping on the cap. Also with alloys you're supposed to put copperslip on the face that mates to the hub as well for exactly the same reason so you can actually get them off again.

Or just use plastic valve caps and save yourself all the galvanic corrosion problems.

onto the

pliars,

My son had the same problem with the sensor ones on his Laguna. I got them off without damage by spraying them with WD40 and then setting some Mole grips so they just lightly squeezed the the part of the thread screwed onto the valve body. After squeezing them all round a couple of times, keeping them liberally coated with WD40, they came off fairly easily. You still might have to grip the valve body itself of course. If they don't free off the first time, be patient, keep going round until they do. Squeezing them lightly, distorts the caps just enough to break the corrosion bonding the cap to the valve body, and allows the WD40 to get right up into the bonded thread. If you refit the same type, put a little grease on the valve body thread. Waterproof grease if you've got any. Mike.

There's proper grease you can get to stop galvanic corrosion. We use it on our glasshouses when using steel bolts and so on on the aluminium frames. I expect you can get it from anywhere dealing with building things with alloy.

Strange but true: my 98 Primera GT has alloys and they have never once been as much as slightly stuck when removing them for servicing - and I have never applied coppaslip or anything else! OTOH, the first time I removed the alloys on my girlfriends 99 Seicento, I had to employ a lump hammer + piece of wood to administer the necessary force to free them ( I now use coppaslip on this one).

Stuart Sharp

We use it on

aluminium frames. I

things with alloy.

Fair enough, but anything that keeps water out of the thread will be as effective. Without water, any galvanic corrosion between the cap and body is highly unlikely. Mike.

Be careful you don't unscrew the valves from the wheels themselves. I speak from experience.

I had to stick the spare on and drive to a tyre place to get the valve refitted (sans cap of course!).

Rich.

Is that the worst that can happen? I never imagined the actual valve was attached to the tyre in this way. I was worried about snapping the valve off - but I guess that can't happen?

Thanks

The valve's not attached to the tyre, it's a pull fit through a hole in the wheel. I haven't done it but I'd imagine if you twisted it enough it would tear away from the wheel.

John

On my alloy wheels the valves screwed in, and were secured by a nut on the inside.

Rich.