Petrol leaking from filler cap

Engine Oily Bits, Ignition, Fuelling, Cooling, Exhaust, etc.
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johnnydog
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Re: Petrol leaking from filler cap

#11 Post by johnnydog » Sat Mar 06, 2021 4:10 pm

One point I didn't mention - the visable filler neck under the petrol flap is actually part of the body of the car, and a change of tank wouldn't affect it. There is a flexible hose inside the boot that joins the neck of the filler to the tank body.
Just checked the parts book - the very early tank was part no. 306136 whereas the later Mk1 tank was 514526, alrhough any differences wouldn't alter the neck where your issue is. The tank and fixings are all the same in the two books, although the actual twist AC style cap changes part number - early Mk1 614024 and then the later Mk1 707358 and 618389.
I have attached pictures of the early and later parts book for you to assess all the info.
It refers to two prong and three prong internal and external fixings for the cap in the later Mk1 book relative to body numbers (on the screwed plate covered in paint on the suspension turret) where you car seems to differ.
Hope this helps...
20210306_155451.jpg
20210306_155505.jpg
20210306_161253.jpg
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20210306_155519.jpg
Register Member no. 1596

1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

johnnydog
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Re: Petrol leaking from filler cap

#12 Post by johnnydog » Sat Mar 06, 2021 4:19 pm

Don't know why I've ended up with an upside down attachment of the tank :roll: (which I can't seem to delete....) but you get the jist.....
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1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

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TobyC
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Re: Petrol leaking from filler cap

#13 Post by TobyC » Sat Mar 06, 2021 6:48 pm

Many thanks. Just checked and too many layers of paint to make out the body number but as I have the 3 prong version it would suggest my body number will fall within the ranges in your extracts. I'll take off the plate and clean the paint off so I can note the body number just for the record.

Ordered some fuel resistant gasket sealant and a replacement neck extender so I'll fit that when it arrives and hopefully I'll get a better seal with the original neck and the new cap will seal properly.

I'll keep looking for an original 3 prong cap in the meantime and having the part number will help enormously - thank you!
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triumph body number.jpg
Toby Crayden
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1965 Mk1 Triumph 2000
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wild bill
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Re: Petrol leaking from filler cap

#14 Post by wild bill » Sat Mar 06, 2021 9:06 pm

Hi John, hope you and yours are well.
I was looking at your tank parts lists, and a three point cap, BC15 part No.616924 is listed.Could this be the mystery cap?
Just a thought,
Take care,Bill.
Bill Young
1967 MK1 2000 MSS8E
1971 minivan IUI1588
1981 minivan TDS40W Now PMY453W
1962Greeves Sports Tourer 24DC 114 GGD
1998 Honda CB750, Deep Candy Apple Red.13500 Miles R191DVR
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Re: Petrol leaking from filler cap

#15 Post by johnnydog » Sun Mar 07, 2021 12:19 am

Hi Bill,
We are both fine, thanks - had the AZ jab last weekend, which was great for my peace of mind!
I didn't realise that a small detail of a petrol cap was made so over complicated by Triumph!
I have only ever known the fitting like those in my photos. If any of my Triumphs that had a locking petrol cap, I have got rid if them for the chromed AC twist non locking cap shown in the pictures. The locking petrol caps were usually the same - an alloy adaptor collar with a cork seal that mounts onto the neck by a twist action which tightens it with a tapered lip against the back of the neck. There is a crude little screw to secure it. The locking cap then has internal lugs which lock into the inside lip of the collar.
The earliest Mk1 I have ever had was a 1966 'D' reg, which also had the neck and cap shown in my photos.
Maybe someone with an earlier Mk1 than that may be able to help you with more info.
Register Member no. 1596

1967 Mk1 2000 in Gunmetal Grey
1969 Mk1 2000 in Royal Blue
1970 Mk2 2000 in Valencia Blue
1972 Mk2 2.5 PI in Triumph White
1973 Mk2 2.5 PI in Sienna Brown
1976 Mk2 2500S in Carmine Red

bigestate
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Re: Petrol leaking from filler cap

#16 Post by bigestate » Sun Mar 07, 2021 11:08 am

I wont be of too much help here, my February 1964 2000 had a screw on cap, pretty sure it was that car and my other November '64 had the standard twist type.
They all tend to leak after a while as the lips on the actual steel tank necks wear with constant twist on twist off use with the caps.

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Re: Petrol leaking from filler cap

#17 Post by Rod 2500S » Wed Mar 24, 2021 6:04 am

Hi all
as a matter of interest it is possible to rebuild your AC style filler caps. attached are pics of my oil filler cap which is of the same design as the petrol cap. Mine looked tatty so I drilled out the rivet and replaced the seal with some oil proof synthetic plastic I had laying around. Works perfectly as long as you get the right plastic (or neoprene rubber???)
It should be the same for the petrol cap.
I used a Stainless steel bolt and Nyloc nut
HTH
Cheers
Rod
Attachments
oil filler cap 2.JPG
oil filler cap 1.JPG

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