Fuel cap seals

[LarryH57]

I have a collection of fuel filler caps for my Lwt and I have heard of the importance in getting a proper seal in them. The first one has a paper seal or rather what is left of it, as in the photo. The other two have very thin black rubber seals and the others none. Why are there two options and which is correct? 

Equally the tank needs a seal round the filler hole and the one I removed did not have one!

Edited August 24, 2020 by LarryH57
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[ruxy]

12 hours ago, LarryH57 said:

 

 

Edited August 24, 2020 by ruxy
posted twice in error

[ruxy]

The cap seems to be correct,  the remains of that seal is of wrong type  - I blame a LR Comic that did a article many years ago - the writer unaware that that type of seal (that needs to be soaked overnight to prevent damage when fitting to the cap intended for it) that particular type of cap pre-dates your cap...

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.

That cap does not rely on any seal fitted to it.  Originally your tank would have a cork crumb composite seal fitted in the tank top filler ring gutter.  They cream crackered and are a hazard.  It was superseded to a fuel resistant buna -  Part No. NRC6836

https://www.lrseries.com/NRC6836-FUEL-FILLER-CAP-SEAL-RING-NEW-REPLACEMENT?search=fuel cap seal

Plug temp. or blank the stem pipe hole , fit new seal , pour in 1 pint of petrol & tip the tank upside down to prove all is working as it should.

You can always put the plastic peg to your mouth and blow to test the cap is OK ,  cap positioned as normal & upsidedown..

New genuine tanks I have purchased from franchise dealership ISTR no cap / no seal.   However ISTR purchasing some Ex-MOD (surplus) + the sliding filler neck.

NRC6836  -  Land Rover were a bit late with that change,  mid-1970's I used a O ring splicing kit to DIY using round strand  Viton , then I improved with square section - that probably came from the standard lub. oil canister seal.

 

Edited August 24, 2020 by ruxy
spelin

[LarryH57]

Thanks Ruxy.

So just to check I should fit NRC6836 to all my filler caps if they have none. However I guess the one  filler cap I own with the white nylon peg broken off is scrap? I have more caps than fuel tanks luckily.

Next to consider is the tanks themselves, as I assume they need a seal too?

[ruxy]

2 hours ago, LarryH57 said:

Thanks Ruxy.

So just to check I should fit NRC6836 to all my filler caps if they have none. However I guess the one  filler cap I own with the white nylon peg broken off is scrap? I have more caps than fuel tanks luckily.

Next to consider is the tanks themselves, as I assume they need a seal too?

Yes , effectively scrap - I have had a couple thrown to one side years ago.  It was when I found one at filter base of the sliding neck , taking a better look at it - I then worked out how the cap works , until then I had just assumed it was something to help stop the rattle from the neck.   I could possibly assemble the full history of caps back to the earliest.  One I don't have is listed in S2A military parts as a  ' pressure cap'  -  but not aware of what it was all about.     The cap used late S2A , S3 &  for coiler aux. tanks - nowhere in such as any Repair Op. Manual  or User Handbook - have I ever come across a official Solihul of operation or maintenance checks/procedures.   I do have the odd mag. going back to early 1980's , telling how to fit the early wide seal composite fibre seal on this last cap.     Due to the lack of official publication by LR - I sus. that it is their way of absolving themselves of all blame in event of accidents - and there have been some reported over the years.

[ruxy]

1 minute ago, ruxy said:

Yes , effectively scrap - I have had a couple thrown to one side years ago.  It was when I found one at filter base of the sliding neck , taking a better look at it - I then worked out how the cap works , until then I had just assumed it was something to help stop the rattle from the neck.   I could possibly assemble the full history of caps back to the earliest.  One I don't have is listed in S2A military parts as a  ' pressure cap'  -  but not aware of what it was all about.     The cap used late S2A , S3 &  for coiler aux. tanks - nowhere in such as any Repair Op. Manual  or User Handbook - have I ever come across a official Solihul  description of operation or maintenance checks/procedures to be adopted.   I think it possible for the breather filter thinghy to get choked up  ?     I do have the odd mag. going back to early 1980's , telling how to fit the early wide seal composite fibre seal on this last cap.     Due to the lack of official publication by LR - I sus. that it is their way of absolving themselves of all blame in event of accidents - and there have been some reported over the years.

 

[LarryH57]

Thanks again Ruxy.

Other connected questions;

What colour were fuel caps originally in a 1980 Lwt GS? Mine have been have been roughly coloured red, possibly using a paint brush or mop! There is also NATO green on them?

Also on one of my fuel caps the inner circular plate to which the chain attaches, can actually be pushed round and round, whereas all the others are fixed. Strange!

[ruxy]

The  'genuine' complete tank assemblies I have purchased - the caps were black as the tank , they were secured in place with a type of HD silver cloth reinforced tape (similar to some parcel tape).  I remember pulling the paint off with the tape.   Spare caps purchased a few years ago - almost certain just plated finish , can't put my hand on one just now to check.   As far as I can recall - all the Ex-MOD LWT I have purchased direct have all had red painted caps & probably brush finish.

Are you able to post photograph(s) of that strange cap  ?

[Genem]

The caps will have been painted in service - Red for petrol, yellow for diesel, it was standard practise.