Hi,
I have just fitted a Moke Club new rubber seal to my English Moke (large type) fuel cap. It is a good fit but my only concern is venting of the tank. When I opened it again there was the sound of a rush of air into the tank. I cannot see any vent in the cap or tank itself - something in all years of owning my Moke that I have never really thought about. Could anyone assist me here - perhaps the vent is blocked and did not show as my old seal was not effective. I replaced the seal after a rather quick stop when petrol came out of the full tank !
Richard
Dorset GJB 121C
Fuel tank filler rubber
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Re: Fuel tank filler rubber
The tank on my Aussie (top fill) has a breather pipe on it. This runs along with the feed pipe to a high point in the engine bay. The tank on the English make, which is pretty much the same has a breathable cap on it
So really my reply wasn’t much use was it….. ow I think about it!
So really my reply wasn’t much use was it….. ow I think about it!

Come on summer
- Dean
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Re: Fuel tank filler rubber
Hi Richard,
I always thought the UK cap was identical to the Land Rover cap of the time which had a vent attached to the underside of the cap.
Does your cap not have any protrusions on the underside? Like this:
If so, this is what those bits are supposed to do.
That white nylon peg IIRC has a spring loaded filter and is the breather , the brass clack valve has a spring loaded ball (stops vent from spillage in event of a roll-over). Venting is via the annular between the cap sandwich layers.
Source:https://hmvf.co.uk/topic/42234-fuel-cap-seals/
Dean
I always thought the UK cap was identical to the Land Rover cap of the time which had a vent attached to the underside of the cap.
Does your cap not have any protrusions on the underside? Like this:
If so, this is what those bits are supposed to do.
That white nylon peg IIRC has a spring loaded filter and is the breather , the brass clack valve has a spring loaded ball (stops vent from spillage in event of a roll-over). Venting is via the annular between the cap sandwich layers.
Source:https://hmvf.co.uk/topic/42234-fuel-cap-seals/
Dean
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- r.crumbleholme
- Posts: 18
- Joined: Wed Oct 22, 2014 18:44
Re: Fuel tank filler rubber
Thanks Nigel & Dean for your prompt replies.
I went for a run yesterday but did not get the air noise when I opened the cap to take the attached photo just now. You will see that there does not appear to be a vent in the cap - the top side is slightly domed and solid. This cap was like this when I bought the car in 1968 ! No sign of a vent in the tank neck either. No mention of a vent in the Workshop manual or the illustrated parts listing booklet). Perhaps I am concerned unnecessarily !
Richard
Dorset GJB121C
I went for a run yesterday but did not get the air noise when I opened the cap to take the attached photo just now. You will see that there does not appear to be a vent in the cap - the top side is slightly domed and solid. This cap was like this when I bought the car in 1968 ! No sign of a vent in the tank neck either. No mention of a vent in the Workshop manual or the illustrated parts listing booklet). Perhaps I am concerned unnecessarily !
Richard
Dorset GJB121C
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