Fuel tank filler rubber

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r.crumbleholme
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Fuel tank filler rubber

Post by r.crumbleholme »

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
Nigel(no top)Sykes
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Re: Fuel tank filler rubber

Post by Nigel(no top)Sykes »

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! :roll:
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Dean
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Re: Fuel tank filler rubber

Post by Dean »

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:
20200823_195622.jpg.5ae920e8dfc50b0362360052de5e3c20.jpg
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
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Re: Fuel tank filler rubber

Post by r.crumbleholme »

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
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r.crumbleholme
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Re: Fuel tank filler rubber

Post by r.crumbleholme »

Hi

Still getting the problem of a partial vacuum in the tank due to air being able to get into the tank as the fuel is being pump out. I guess before I put a new rubber on the cap, air was able to get in to prevent this happening. I cannot see a vent pipe on my tank - I have seen a new tank for sale which has a vent pipe just below the neck of the filler (see photo). I guess that this vent pipe should have a pipe to discharge any fuel through the bottom of the tank enclosure (saloon minis have a similar set out). Both the tank and cap are original as I have owned this English Moke since 1968. I guess the cap has never sealed properly until I replaced the rubber.
It would seem that most Mokes have a vented cap and certainly the one that Leo sells at M Panels is like this.
Richard
Dorset
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r.crumbleholme
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Re: Fuel tank filler rubber

Post by r.crumbleholme »

As a final post - I have purchased a new vented type cap from Leo at M Panels. I still can’t think how I have had this Moke for over 50 years - I must have always had slightly defective rubber seals !
Richard
Dorset
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