C1 Gas leak

[Jim K.]

I have gas stain on the outside (drivers side) just under the gas fill up door towards the left rear tire. I have added a new cork gasket in my non-vented gas cap and it looks (I see an even impression) and feels secure. I replaced the filler hose and clamps between the tank and filler tube, replace the vent tube and overflow tube. I don't have gas stain (wetness) on the inside, just outside. I just purchased a repro vented gas cap to see if that would work but I still get gas leak stains under the gas fill-up door. Can anyone help with the id or solution to this problem. Thank you in advance.

[Wayne P.]

Re: C1 Gas leak

When you do a right turn, a near full tank will leak thru the vent in the cap. You can help by not filling completely. Best to go with a non-vented cap if the tank is vented.

[Mike Harpster]

Re: C1 Gas leak

Jim,

I had a very similar problem and it ended up being the cap. I went down the same path with buying a repo vented cap and still had a leak. Attached is an old post from John Hinkley giving the steps he uses for getting rid of the fuel smell in C1s. I followed them and I now have absolutely no problems. I fill the tank of my 1962 full and even when making hard right turns have no leakage.

To make absolutely sure I had a good cap is took off my filler neck and took it to the auto parts store. At the store, I tried a number of caps and blew into the end of the filler neck to make sure that it was sealed.

Hope this helps,
Mike #40,893

"I've been through this (and fixed it) on several C1's:
1. Get a non-vented (no valve of any kind, just a rivet) aftermarket cap (to stop the leakage through the cap).
2. Replace the old, dry-rotted filler neck hose, with the correct barriered fuel filler hose (not radiator hose); NAPA sells it by the foot.
3. Make absolutely sure the tank vent hose that runs into the filler cavity is open and not cracked/rotted; replace it - it's cheap.
4. Make sure the drain hose still exists from the nipple in the bottom of the filler cavity down through a rubber grommet in the underbody so spillage drains out on the road; 99% of these hoses are missing, so spillage dribbles down INSIDE the underbody instead, pools, and causes major fumes/odor in the cockpit.
5. Use strip-caulk all the way around the tank cover when you re-install it; that joint was sealed for a reason.
6. Check to make sure some dolt didn't seal up the large ventilation holes in the underbody below the fuel tank; they're there to continuously ventilate that compartment.
7. "While you're in there", add a dedicated ground wire from the tank sending unit to the frame. "