MTFCA Forum

The gas cap on my 1927 coupe is "stuck". Any suggestions on how to remove it? What kind of wrench?

Picture of it would help rather than to assume what cap you have. It could be cross threaded as opposed to gummed up

Can you soak a little lacquer thinner or alcohol around the tight fit?

When did you last remove it ?

There is a paper “gas cap gasket” that goes on the cap. 90% of its job is preventing the cap from “taking a set” and getting stuck.

RajoRacer wrote: ↑

Wed Oct 14, 2020 1:49 pm

When did you last remove it ?

Good question! On all 26-27's except fordors, it is not necessary to tighten the cap, any more than snug. Even if it vibrates loose, the tray around the filler would catch it before it fell and was lost. As said above, a gasket should be used under the cap. If the cap is an original 26-27 cap, they were cast pot metal which tends to swell over time and if you haven't removed it in years, perhaps that is what happened and is preventing it. Its doubtful if it is an original pot metal cap that it has swelled over a short period of time, so if it hasn't been long since you last removed it, swelling shouldn't be the problem. I have an original cap for my 27 coupe and keep it for originality, but regularly use a brass repro cap because they won't swell.

Standard cap?

If it is anything like my original cowl tank setup, the cap is down in a trough surrounded by a berm to catch any spillage and allow the spillage to flow out a drain. My original cap (I think it is aluminum) has a raised rigid handle going across from one side to the other. Try taking a set of channel-lock pliers and position the grips downward and position each grip on each side of the rigid handle on the gas cap then turn counterclockwise. If it does not budge, gently tap the cap all around with a hammer. Jim Patrick

The cap has no bearing on the body style! That cap was introduced sometime in 1924 I believe, and as noted above is pot metal. If you aren't careful, you will break the ears off of it. If you do, there are very good looking reproductions that look the same.

The late gas cap has the metal cover or baffle underside to prevent gas seepage up the vent holes.


Here is original late cap:

Lang's offers a real nice reproduction of the later cap.

Like to always put a dab of Vasoline on the threads of the cap from time to time, keeps them from sticking with modern fuel that has dyer additives and other stuff during formulation for environment or seasonal and various states requirements

Original Smith wrote: ↑

Thu Oct 15, 2020 11:30 am

The cap has no bearing on the body style! That cap was introduced sometime in 1924 I believe, and as noted above is pot metal. If you aren't careful, you will break the ears off of it. If you do, there are very good looking reproductions that look the same.

This is True, and I totally agree. The point that I made in my post, above (and Jim's post, as well) is that even if the cap were to vibrate totally loose from the threads, the the metal dam or trough around the filler will catch the cap EXCEPT on fordors which used the earlier under the front seat mounted gas tank,

Terry

If the cap is loose on an open car '26-'27 the fumes will whaff and be smelled by the passenger. Did happen to me, wife noted the gas smell as we ride with the windshield tilted out on the touring for ventilation. The cap was loose, as I have just dropped it on without threading.

Oh. She won't ever forget when I was filling that cowl tank and she was in the seat, my grip slipped on the gas handle, and tilted the nozzle, spraying gas up and over the that gas trough, and thru the open windshield. Cost me that day, including a new pair of bluejeans for her

Use some plumbers putty and build a dam all the way around the cap where it screws into the tank. Make it tall enough to allow some penetrating liquid to pond around the cap. I like Gibbs penetrant. Check it daily and fill up as needed. Ever so often during the day, smack the cap with a hammer. It might take a few days, and assuming the threads were o k when last installed, the cap will come out. My last one took 7 days.
Good luck.

DanTreace wrote: ↑

Thu Oct 15, 2020 12:38 pm

Terry

If the cap is loose on an open car '26-'27 the fumes will whaff and be smelled by the passenger. Did happen to me, wife noted the gas smell as we ride with the windshield tilted out on the touring for ventilation. The cap was loose, as I have just dropped it on without threading.

Oh. She won't ever forget when I was filling that cowl tank and she was in the seat, my grip slipped on the gas handle, and tilted the nozzle, spraying gas up and over the that gas trough, and thru the open windshield. Cost me that day, including a new pair of bluejeans for her

Dan, I agree, but not having an open 26-27, I forgot about that senario. In that case I guess it would be best to keep cap snug, but using a gasket would probalby help sticking, as would using a brass cap and saving your original pot metal cap for show.

In the immediate problem, Kroil is your friend - it may take 2 or 3 applications over as many days, and be gentle, but it will work. Give it time. And be gentle. Let it work, tap it gentle to work it in... it will eventually loosen.

Long term - while it's not "authentic" get a brass repop cap. they won't do this and you can save the original for when you're chasing a 100 point car.

Once you get it off, it may be advisable to clean the threads with a bench grinder mounted with a fine wire wheel brush. Pot metal does corrode and expand over the years and that may be what happened with your cap. Put Vaseline on the cap threads when screwing the cap on. Jim Patrick