Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Leaking tyre valve

This morning was cold, crisp, but dry fine weather and I thought ideal to take the Mog for a spin. Into the garage and ... one flat tyre.

Jacked the car up – no sign of a puncture so out with the washing up liquid solution. After painting it all over the place (rims etc) eventually got bubbles around the base of the threaded tyre valve, just above the locking/tightening nut. Quite a lot on what was the flat tyre (after pumping it up) - big bubbles (in photo 1) and, checking the other four wheels, a little bubbling on two of the others (as in photo 2).





As I’ve only had to top up the tyres a little (twice) since I had the car (Jan 15) - last time just before Christmas - this has not been a long-term issue. So I am not sure what has caused this (on more than 1 wheel) – perhaps the cold weather causing sufficient contraction to give a slight leak around the internal sealing washer? Not having had wire wheels or bolt-on valves before, I have no experience and not 100% sure why its happened, what this could be or what to do.

Anyway, thanks to advice from MWS (who were really helpful), just tightened up the locking nuts (taking care not to over-tighten or thread damage may occur)and leaks all stopped.

I seems this nut pulls the threaded valve stem up through the wheel against a rubber sealing washer inside. Anyone else had this issue ?

Not that problem, but I've had a hose leak when the metal coolant pipe contracted in very cold weather. So it only leaked on frosty days and took a lot of tracking down.

Your problem is definitely temperature related.

Our car was November 2014 delivery. No problems until May 2015 when I found spare was flat, soap test revealed leaking valve stem which was only finger tight. Tightened nut - all OK and has been ever since. All other wheels were OK.

Then around Christmas discovered that one rear tyre was flat. Based on previous experience I tightened nut on valve stem and pumped tyre up. All OK since.

It looks as though there is an issue with how tight these nuts are at assembly and the amount of relaxation as the washers compress. I have now rechecked all 5 wheels and a couple moved a little bit.

Good tip.

Thanks for the tip.

It's an item that's on my service sheet to check. I just use a deep socket and do it by hand.

Great tip, I will try and store in my memory banks.

Ever so much easier to access than the valves on my 15" black rims - nothing a box spanner can't reach though!

Thanks for the tip - just tweaked my drivers front - see if that is the cause of my slow deflation

This is the arrangement:

Dave - useful photo to see how the washer pulls up inside. From the image I guess there's a slot on the internal head to hold with a screwdriver while the locking nut is done up onto the rim. With the tyre on, if the valve itself just turns, then I guess its tyre off or perhaps gently using two locked nuts on the valve stem to hold the stem still while tightening the locking nut.

Luckily mine just tightened with no problem. Tyres still fully inflated - just had to try them out on Fri (dry and sunny here if a little cold).