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Leaking fuel filler cap


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As the title says - my fuel filler cap leaks fairly badly when I go round a left-hander <_< I've replaced the rubber seal on the cap itself but it's made no difference (surely Britpart can't mess up a simple seal?), another suggestion is "blocked breather" but I can't see how this would cause, or stop, a substantial loss of fuel through the cap?

Mine is the early type - black flip-up cap with a lock on it, not the type behind a little door.

(Here's one that's on eBay)



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Mine was like this too - brought me back to my old Mk2 Escort in the fields at home, it had an old Esso tin with a copper pipe brased in for a fuel tank between the front seats. When it wouldn't run we had another way of getting our kicks....

Anyhoo the reason its doing it is because there's a baffle inside the filler neck that you must be missing like I was... don't ask me where to get them the 3.9 conversion has meant it's not a problem for me any more.

So in the meantime you know how to pass the time :D

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Mate had this

Its not closing on the seal enough due to wear give the item a "Tweakette" with LR special tool No 1 to make the clip on the cap lock harder onto the assemble

If you wnat to be technical here A "John White number 3a" should be big enough :lol:


PS I am going to be in sooooo much trouble when Mr "I have a snap on chest with a draw dedicated to hammers" read this :rolleyes::lol:

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It never used to leak - surely a baffle won't have just fallen off or gone missing inside the tank? :blink:

Open the filler cap - is there a second tube within the filler neck - you'll be able to simply pull it out. If there isn't and you just looking down the filler neck then it's missing...

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I had a dig around in my manual, and the parts list seems to indicate tyhat UK and Europe models did not all have the extension tube. It would be nice to have though, as it would save havuing to carry a spout or funnel for my Jerry cans.

Here is the parts listing, if you need to order any bits:


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Well I knew nothing about it until a fella cold called on me one day. He has a late '70's two door with a 3.5 Mazda diesel conversion using the original RR tank. We were chatting about something and he opened the original filler cap to reveal this 'extension' (bloody good idea btw) which I took to be a baffle.

It certainly acts as a baffle as there's a thick rib just short of its leading edge inside it that constricts the neck so when the fuel surges up it's stopped by the rib.

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Have you tried putting a second rubber washer on? can't see from the pictures that there is much else to go wrong, but the rubber not sealing, so an extra thickness of material might be enough to give it a decent seal.


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  • 2 weeks later...

Well I sorted it, and none of this hammer nonsense :rolleyes: if you remove the rubber seal on the cap, there is a phillips screw holding the plate on. Behind this is a large spring that pushes down to make the seal. Obviously 20 years have passed and it's done a ScrapIron and sagged :ph34r: so a bit of tweaking about and it's been restored to its original springyness, or some approximation thereof. If it doesn't work 100% then a bit more tweak or perhaps a supplemental spring may be in order.

Curiously, hanging round the lab, the springs look very similar to the Volvo 303 diff lock actuator return springs. Hmmm, wonder if Jez would miss one :ph34r:

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