Well, just returned from Donnington and an old problem has re-surfaced,petrol all over the rear quarter …and a light bulb just switched on over my head…is it due to my petrol cap being of the locking type?
Because there are two cut-outs in the sealing flange?
Can we have a straw poll…will those with this problem let us know if their petrol caps are locking or not…
Thanks
John 
Mine leaks, and isn’t a locking type…
Cheers
tim
Mine locks and doesn’t leak.
But forgot that I get major fumes in the cockpit when the tank is full
… as I was reminded, after filling up on the way to Donnington.
Regards,
Stuart
Mine locks and leaks
One day I will get around to fixing it using one of the many techniques suggested. In the meantime I just never fill the tank more than half full
Rohan
My tank was only half full,or is that half empty?,but must be caused by throwing it around a bit and fuel sloshing up the filler pipe…
John
Mine is original and is non-locking. I have to replace the rubber sealing ring regularly because it splits (I just cut out another piece from an old sheet of dubious quality). It then seals OK.
Mind you, I has to fiddle around with the centre spring arrangement to get the sealing ring to sit squarely and seal. You also have to get the centre bit to seal at the same time. I used rubber grommets cut to suit for that - not easy but possible.
Dave Chapman.
Locks…no leaks.
Haven’t done anything to it since putting it on 20 years ago.
Ralph.
Mine originally locked (wel originally since I bought the car??) and didn’t leak and I have since changed it to a BRAND NEW shiny locking type and it stil doesn’t leak !! 
I did find when I first got the car that it DID leak and this was because the PO had fitted the locking mechanism the wrong way round on the lock shaft and it was not allowing the seal to sit square on the neck !
Cheers and have fun
Mine doesn’t lock and leaks all over the rear ? panel.
Hamish.
Mine doesn’t lock and doesn’t leak.
locks and leaks. But I have made a very simple version of this:
out of an empty vitamin tablet bottle - very Blue Peter. No leaks yet but will let you know after a track day. If it works I’ll post photos.
best regards, iain
Mine locks and leaks all over the rear ? panel
Will see what cures you chaps come up with and will get it fixed !
Matt
Mine locks and has never leaked in over ten years. Guess im lucky
Dave
Locks & no leaks even when full… Can be a bit tight to unlock & I have fitted a new rubber gasket (cheap).
Jeremy
Hi There
Locks and no leak. Having that have not had the tank more than half full… will be filling it up for a long drive next weekend so will report back if it does.
Berni
No lock, no leak - when I used the car regularly I never had a problem .
Mine did leak, but I fixed it! (smug grin)
I have a locking one which turned out to be vented - there was two small holes in the seal carrier top and bottom. I filled the bottom one with solder and now appear to have no leak!
Thought I’d cured the smell inside too when I replaced the filler hose and re-secured the breathers but that has returned after I filled up 
Robbie
I’ve got the same two holes in mine,I’m out to the shed to fire up the soldering iron as there are other vents…
Will report back later
John
No lock, leaks but only when the fuel tank is very full. I replaced the thin rubber seal retained by the cap and gained precisely no improvement.
This should be posted in the +2 forum, Cleggie; afaik it has never been an issue with the +0 Elan because the tank is under the boot floor and does not have those vent pipe thingies found in the +2 luxo-barge! 
Cheers,
Pete.