Stuck Valve Caps

[markys]

It’s a funny one our Merc has metal valve caps and they have corroded onto the valves, well three out of four have. I have tried socking them in WD40 over a number of days buts it’s not helped and they are stuck fast. Any ideas?

[V8forweekends]

WD40 isn't very good for this kind of thing - you should try Plus Gas or Loctite Freeze and release.

[Amused2death]

Boiling water, bit of cloth round the valve cap and a pair of pliers.

[haggishunter]

Tap with a small hammer may loosen it then try pliers.

[Sheepshanks]

Hmmm...not sure I'd want to be leave WD40 on rubber tyre valves for days.

If they weren't stuck they'd have been nicked. I gave up after the second set went.

[996TT02]

Two pairs of pliers? Can't be THAT stuck.

As you have found out, no WD40 or any other lubricant of any sort, left for eternity, will ever help release any corroded part. Its only use is when the item has actually released and is turning.

However there exist products that actively attack corrosion and these can be tried. Together with the freeze stuff though honestly I have tried (a lot of) the latter on some seriously rusted on nuts to no avail.

[Accelebrate]

Pour a kettle of boiling water over the cap and then twist with a couple of pairs of pliers. Has worked for me a couple of times.

Refit with a dab of copperslip.

[TooMany2cvs]

Yep, they do that. If brutality and proper penetrating oil don't work, you'll need to get the valves replaced. If you go for metal ones again, then make sure you put a smear of copaslip on the threads.

[Rotaree]

Drive to a tyre fitters and have them replace the valves - Kwik Fit (yes I know the PH bias but they're not all bad) will do it free of charge.

[graham22]

I bet they're alloy valve caps. Someone will probably explain better than me but the corrosion between the two types of metal in the cap & the valve will effectively weld them together.

Using pliers etc will only result in the brass part of the valve coming away from the rubber part before it unwinds. Either dremmell the valve cap down it's side & 'spread' it off or get new valves fitted.

Steel caps seem less likely to seize in this way but I'd still use cappaslip.

[Turkey]

If you're going to attack them with pliers, make sure you hold the rubber stem leading upto the valve very tightly, to stop it being stressed too much, with molegrips for example, a rag wrapped around the stem might help avoid damage to the rubber. I didn't hold the stem place when I set about removing a seized alloy nut on mine, and I broke the stem where it slots into the wheel, and the tyre deflated rather quickly.

[bristolracer]

I had to dremmel mine off.
Alloy caps on brass.
Next time you are in a tyre centre just ask for a handful, they have thousands lying about from all the valves they replace, i just grabbed some off the floor.

Wont bother with fancy caps again, theres a good reason why they use plastic.

[Steve vRS]

I had this too and needed the valves replacing.

Galvanic corrosion is to blame between the disimar metals.

Steve

[thespannerman]

Rotaree said:

Drive to a tyre fitters and have them replace the valves - Kwik Fit (yes I know the PH bias but they're not all bad) will do it free of charge.

S**t fit will not do it for free, I had a knackered valve on one corner of mine and swung by the local s**t fit and asked them what it'd cost... tried to charge me £25 for the privilege, asked the bloke if he was having a laugh! Got in reply "it's at least a 25 minute job"

Got it done a week later when visiting the folks back home, local garage did it in less than 5 mins and only charged me the cost of the valve

Edited by thespannerman on Thursday 12th March 19:16