RL, RM & RN petrol tanks

[Mike Costigan]

Just curious - those who have a scuttle tank with a screw-on filler cap - does your cap have a cork (or similar) gasket?

I never fill my tank more than around 3/4 full because I get fuel spilling out from the filler; filling up yesterday it just occurred to me that my cap doesn't have any sort of sealing gasket - is that my problem?

[Steve Jones]

Don't know, Mike. I'll go and have a look!

Edit:

Yes, mine does

   

Steve

[Mike Costigan]

Cork or rubber, Steve? And how is it retained?

[Steve Jones]

I didn't want to poke at it too much, Mike, for fear of the obvious happening this close to Moreton but I think most likely cork. If it were to be rubber, I'd have thought it would have rotted away years ago. It's a good  fit into the recess to the outer edge of the cap. You can see the outer edge of the gasket is slightly deteriorated. It looks like it's been there for ever so I'd think it might well be original to the car.

Perhaps a suitably sized O ring in a modern material would do the job?

Further Edit: I've looked again, Mike and it does appear to be cork. However, my Lidl box of assorted sized O rings has some that fit perfectly. Can I post you one?

Steve

[Dave Mann]

    Mine have always had some form of synthetic rubber seal which is slightly larger that the thread so it remains trapped in the thread undercut.

[Robert Foreman]

On the RN and Ulster I have leather washers. You can fill the tank right up to the gunnels and it doesn't leak.

[Tony Betts]

I didn't want to poke at it too much, Mike, for fear of the obvious happening this close to Moreton but I think most likely cork.

Steve

hi steve,

appreciated that one

ive been tinkering with the superports today.

took it out for a run first thing, nearly got hit coming of a roundabout by a young STOOPID STOOPID girl. she looked me straight in the eye, then ignored i was there.

but back to a simular thing as yourself. on a tightish turn i can feel movement in the wheel as the bolt that pinches the wheel moves from one side of the cutout to the other.

if i temp fate and tighten it before morton, sods law says it will break. so ill risk it until after the event.

tony

[Dave Mann]

I'm not sure about leather, a friend had a nasty experience when a wash leather was stuffed in fuel tank of his 1961 bus, it disintegrated causing mayhem in the fuel system.
Nothing unusual in that Tony, I regularly come to rest on mini roundabouts with the surprised driver of a modern able to count all the dead insects in my radiator.

[Hedd_Jones]

Mine had a cork one, untill it fell out. I made one out of card which has been fine. 

The bayinet type on the chummy however leaks like a sieve. So I cannot fill right up as noted.

[Graham Barker]

Be careful about the choice of rubber O-ring. I tested one that I was considering using in a petrol application. I left it in a jar of petrol overnight. It swelled so much the ring thickness was more than doubled. Unfortunately I don't have specs for that O-ring, so can't tell you what material it was made from.  I suggest testing any rubber in some petrol before using it.