I went to check my tyre pressures today.

I have some ebay metal valve caps fitted,which have never been a problem till now.

They are normally finger tight,but today I had to remove 2 with pliers and 1 was turning the rubber valve stem in the wheel.

I eventually removed it with 2 pairs of pliers.

There's been a lot of salt on our local roads recently which I think is to blame.

They are usually poor quality too, so soon corrode. :(

Its the same with any differing metals in a wet environment. I stick to plastic ones. Got a bag of 100 for £1.50 delivered on the bay so have an effectively endless supply. Fancy ones invite thieves and stuff like this.

Its the same with any differing metals in a wet environment. I stick to plastic ones. Got a bag of 100 for £1.50 delivered on the bay so have an effectively endless supply. Fancy ones invite thieves and stuff like this.

Electrolysis.

Corrosion of dissimilar metals .

AKA. Electrolytic corrosion (:

As above steer well clear of metal valve caps really are a pain in the bum

I use a small amont of Silicone Grease on mine (apply with a matchstick in the cap). Never had a problem removing them

I don't have to check - all four of mine were nicked at Christmas  :|

 

Gaz

Never ever had a problem with the old Schrader ones, but they were brass. 

Guessing it is the tatty rubbish bought on ebay which cause the problem.

Never ever had a problem with the old Schrader ones, but they were brass.

Guessing it is the tatty rubbish bought on ebay which cause the problem.

Shouldnt get corrosion as bad because the valve is usually brass too. So made out of the same metal.

In theory.

Never ever had a problem with the old Schrader ones, but they were brass. 

Guessing it is the tatty rubbish bought on ebay which cause the problem.

 

 

Shouldnt get corrosion as bad because the valve is usually brass too. So made out of the same metal.

In theory.

I presume the OP is referring to the (anodised) aluminium ones. If so, then I'd agree that the issue is electrolytic corrosion.

Coincidentally SWMBOs metal caps on her BMW were jammed on when I tried to check her pressures the other day. Two pairs of pliers wouldn't shift 'em and I was worried about ripping the valve stem.

 

Never happened before so I'm hoping it was just the low temperatures, but dowsing with warm water had no effect. Will try again at the weekend and give 'em a good skoosh of WD40 see if that does the trick. Failing that I'll have to get her car somewhere to get the valves changed and stick on plastic caps.

In the old days, it was a Schrader recommendation to fit proper valve caps.  The real Schrader ones at least had an additional seal.  Until I threw all my stuff away, I had some official bumff about it from Schrader.

Schrader was the inventor of the sort of tyre valve which is the 99.9% fitment these days.

In the old days, it was a Schrader recommendation to fit proper valve caps.  The real Schrader ones at least had an additional seal.  Until I threw all my stuff away, I had some official bumff about it from Schrader.

Schrader was the inventor of the sort of tyre valve which is the 99.9% fitment these days.

The "real Schrader" caps in question being the nickel chrome over brass with a rubber cushion meeting the top of the brass part of the valve assembly and a recess over the plunger rod ones?

Yes.  You used to be able to buy them, came 4 in a little tin with a sliding lid.  Red and blue with white script.