gas overflowing from vent line after filling

Disconnect the line to the vent in the tank.

Not to mention there may be a hole in the hose between the outside fill connection and the tank.

if your car has never had any fuel system rubber replaced, it's probably turned into hardened crunchy !@#$^&* and should really be checked out by somebody that knows what they're looking at

current fuel blends usually contain Ethanol, which aggravates the deterioration process on steroids. old school fuel rubber doesn't stand a chance, replacement rubber needs to be 'up to code'

I neglected to mention that it is a 1972. the lines appear to have been replaced in that they are not brittle. marlin jack, you mention that if the tank is so full it could cause siphoning out of the vent line. this is what appears to be happening because it is not a drip. it is significant pouring from the vent line. is it routed incorrectly or missing a valve or something or am I just filling the tank too full? thanks.

do you have "12" and "15"

The reality of the situation in the Pantera, IF you fill the tank to the top AND top it off to the top of the filler neck, the tank "vent" is below that fluid level.

Not only will it leak fuel through the hose to the charcoal canister, IF the fasteners that hold it to the tank are not perfectly tight, it will leak through there as well.

In it's first few years, the car had a reputation for gas fires involving the gas tank.

That is as much for the spilling of fuel on the hot exhausts inside of the engine compartment, but also little incidentals like the vent.


The "check valve-roll over" design was not introduced for the US versions as far as I know. It is something that came along later and was added by many then current owners.


The best solution is not to fill the tank to the top. Stay down about an inch below the vent AND if you decide to update it and change it over to the "anti-roll over design", whatever you do, make sure that the fasteners that you use are solid and not hollow like pop rivets are.

The most ridiculous thing I ever found were the hollow stem pop-rivets that Hall supplied as fasteners for the vent. Those would have turned the tank into a sprinkler head if it was turned upside down with fuel in the tank.

If you use a vented gas cap, you don't need the vent. It would not be a terrible idea to take the thing out and put a solid plug over the hole.

4066 did not. I dont remember there being a cross over date or serial number for before and after?

#3518 72 pre-L has part #12 .. didn't know it was a roll-over valve.

I don't know what the internals of the Pantera's looks like, but this is a Ford type of that period.

All the US cars were required to have the evaporation from the tank filtered through a charcoal filter. #15 in the diagram.

The "breather or tank vent" was attached to the top of the fuel tank with the part we are talking about. #12 in the diagram.

At first it is just a vent with a screen with a fabric attached internally.

At some future point it was changed to a vent with check valve installed into it to prevent or reduce the amount of fuel that would drain through it if the car got upside down.

My car, 4066, did not come equipped with the check valve/roll over valve. Marlins did. I doubt there is much chance an earlier car than mine had one factory installed?

It makes more sense that somewhere in between them there was a change over? Maybe it is a '74 model feature? I see very few '74s to compare features to?

I never heard about a recall to install them on earlier cars?

This is a picture of the original tank "vent".

Inside is just a screen with a fabric over it.

This is the "roll over valve". It is plastic and contains a check valve. Sorry. I don't have a pic of the inside of it.

It is not a Ford part.

Mine on #3518 looks like the "ugly" one in the above picture. Since it is not an easily removable item, I wounder why Ford would put a fabric piece in it. I know that only vapors go through it but in 40+ years I suspect there is the possibility of 1) plugging or 2) fabric deteriorating and falling into the tank. Neither is a good thing. I put in a vented cap to take care of 1) but can't do much about 2). Any experience with this out there?

It isn't a cloth fabric. It is a metal mesh. Looks like it is maybe stainless steel

quote:

Originally posted by PanteraDoug:
The reality of the situation in the Pantera, IF you fill the tank to the top AND top it off to the top of the filler neck, the tank "vent" is below that fluid level...

I am surprised this item is not given as much attention as coolant or amp meter!