Help! My Octavia came (2nd hand) with metal valve caps with the Skoda logo on. Last week the tyre pressure warning came on as the car was heavily loaded. I pumped up the front tyres but cannot move the rear valve caps (even with pliers and WD40). I think they may have corroded onto the tyre valves. Can anyone recommend anything that might dissolve the corrosion or am I going to have to try the garage?

 

thanks

Boil the kettle and then pour boiling water on the cap and try loosening the cap. 

Thanks I’ve just tried that but didn’t work ☹️

@Samstan

The next trial is do it again with boiling water and then pour cold water on right after.

Still a no go ☹️

Rotate the wheel so that the valve is at the top of the wheel. Now put a small amount of PlusGas on the edge of the cap and it will work its way down into the corrosion. After 15/20 minutes have another go.

 

I personally wouldn't be happy about the valve after you'd got the cap off and would be saving up for a new valve at the tyre fitters.

If staying with metal caps once you've got the seized ones off, put a smear of copper ease grease on the valve stem threads before replacing.

1 hour ago, Warrior193 said:

If staying with metal caps once you've got the seized ones off, put a smear of copper ease grease on the valve stem threads before replacing.

 

+1 - This 👆 

Or a little smear of Vaseline on the threads as it can be a bit ‘cleaner’.

I also remove mine towards the end of October and put the plastic ones back on until after the frosts/gritting has stopped again.

 

3 hours ago, Warrior193 said:

If staying with metal caps once you've got the seized ones off, put a smear of copper ease grease on the valve stem threads before replacing.

Once they’re off it’s black plastic all the way!

6 hours ago, inspectorman said:

Rotate the wheel so that the valve is at the top of the wheel. Now put a small amount of PlusGas on the edge of the cap and it will work its way down into the corrosion. After 15/20 minutes have another go.

 

I personally wouldn't be happy about the valve after you'd got the cap off and would be saving up for a new valve at the tyre fitters.

This stuff? https://www.screwfix.com/p/plusgas-formula-a-dismantling-lubricant-400ml/485ht
 (& thanks)

1 hour ago, Samstan said:

This stuff? https://www.screwfix.com/p/plusgas-formula-a-dismantling-lubricant-400ml/485ht
 (& thanks)

Yes, and well worth the money for the time it will save on your first couple of jobs using it.

Ranex or any rust converter will losen them, but i'd try some basic WD40, or other penetration oil.  Let it soak a bit.

6 hours ago, Okedokey said:

Ranex or any rust converter will losen them, but i'd try some basic WD40, or other penetration oil.  Let it soak a bit.

Thanks tried all that and nothing worked so it was a garage job for new valves. Cost me £30 for the 2 wheels so could have been worse!

I prefer the aftermarket, metal valve caps as they usually have an internal O-ring seal fitted - but you need to watch out for them seizing onto the stems. 

Do you mean you prefer the look of them?

 

If so then preventative maintenance is the price to be paid.

 

Because standard plastic valve covers have a built in sealing ring (as do the AC port caps) and do not seize with corrosion.

 

 

Plastic all the way for me now!

if you're committed to metal ones, apply some dielectric grease on the threads before install