Question -what is it? Never seen before

[Domino]

I am encountering something I have never seen before in the 40 years (on and off) that I've had As. I purchased a Fordor driver 15 months ago and took it on tour last April and this past weekend. Both tours included leaving at 9:00 a.m and driving our cars until around 4:00 p.m with stops for lunch and sight seeing. After, both of these tours a black sticky substance appeared on the paint like it was coming out of the gas tank. It apparently flow and then turns tacky like pancake syrup. I have enclosed a picture. 2nd picture is a shot of the tour. It was cleaned up after the April tour and did not occur again until this tour.

Has anyone ever experienced this or have any idea of what this is? As always thanks in advance. Hope the picture shows.

[Bruce Lancaster]

Draw a sample of gas from the plug on bottom of carb, put it on a plate, and see what it does.
My immediate fear is that something new in our wonderful gasoline is dissolving tank sealer and you know have 10n gallons of really ugly paint in there.

[Keith True]

I've been getting that in a couple of cars.I think certain compounds are going out through the cap vent as vapor,then reforming as a paste.It is almost like creosote.It does wash right off with a little thinner.I never let it stay long enough to harden up.It is always gummy when I wash it off.I can't be positive,but it seemed like it happened with the gas that I had used stabilizer in.With fresh gas it went away.I will not use tank linings,so it is not that with mine.I am having a lot of run-ins with tank linings coming apart,and none of them are dissolving back to a liquid.Most of them are crumbling,or coming off in strips like salt water taffy.

[Gary WA]

Have to agree! something in the tank! look inside w/light does your gas guage look clear or same color black stuff? Maybe something in Texas?

[Roadster62]

Evil spirits.

[Domino]

Sponsored Links (Register now to hide all advertisements)

Gas guage is clear - gas can be seen through the glass.

[Mike V. Florida]

Let's hope it's only the gasket on the cap that is affected my the gas.

[Ron in Quincy]

The first tank sealer on the market, about 27 years ago, was not impervious to the additives that started appearing in fuel. Two different " A" people in Sacramento started having problems with their tanks; the sealer showed up in the carburetor throat and intake manifold, looked just like tar. Another man had a mustang with a new rebuilt 289 engine, he had used tank sealer, he ran it long enough that the desolved tank sealer got in the engine, it seized the engine and wipped it out. The radiator shop suggested using ascetone; we flushed both of the " A" gas tanks using 3 gallons of ascetone in each one. Once we got the tanks clean they never had any more problems.

I advised the owner of Sacramento Vintage Ford what we had discovered; he pulled all the tank sealer; It was several months before he obtained new tank sealer that was impervious to the fuel additives.

Both the A'ers had sealed their tanks during restoration as a preventive measure against against rust.

Ron

[Brentwood Bob]

I have noticed a gummy residue with the breakdown of an older tank liner. This froze a carb. and when the intake was removed the residue was in the intake up to the intake valve. Bob

[Brentwood Bob]

A second model a had a gummed up carb. Both A's had to have the tanks flushed with fresh gas. See thread "Black stuff in the gas tank". Bob

[Brentwood Bob]

Ron, With the acetone flush, what happened to the gas gage float? I installed a new synthetic one. I wonder if acetone will melt it. Bob

[Phred]

I had a similar occurence recently with my '28 radiator cap. I had put some new leather gaskets in both the radiator and gas caps. It appears that this batch of leather gaskets are treated with some sort of "wax". Heat from the radiator would melt the "wax", which would run down the radiator shell. Then the gasket would shrink to an unusable size in a matter of a couple days.
I have not had this problem with my gas cap though, as it does not get as hot. We run 10% ethanol around here.

[Keith True]

Another thought I just had.Years ago I had black stuff leaking out from under the cap.I had bought a new gasket,and it was a nice composite material that sealed nicely,and let the cap turn like it was greased.Well,the stuff the gasket was impregnated with was evidently petroleum based as it leached out and ran all over the top of the tank.I don't think it was in the quantity you have though.After a dozen or so wipedowns it stopped,but the gasket shrunk up and cracked.I think you're going to find it is just compounds in the fuel,or additives.As somebody pointed out,put a little gas in a pan,1/8 inch or so and leave it in the sun.You will wind up with a gum that looks exactly like what you have on your tank.I don't think it is a tank lining coming apart,they usually go as a big mess.It might be a sealer made up by an old timer,before sealers were available.They used to mix up Permatex # 2 and alcohol,50-50,and slosh it around in a tank.I have not seen the results of it with modern fuels,but that is one thing the alcohol might break down to a liquid.Then again you say your gas looks clear in the glass so that kind of rules that out.

[1931 flamingo]

Back in the late 50's with a model A roadster rescued from a field in stony point, NY ($75, w/reblt engine!) had similar problem in tank, tried commercial steam cleaner to try to remove as much as possible from the tank.
Paul in CT

[1928Pickuppain]

I have the same problem it just dosent come out of my cap if i put ethynal gass in it, it will go from gas colored to tea colored to black. I have a little spickit coming off my sedimint bowl so i can fill up a glass with gas and see if theres water in it. This spickit got cloged compleatley with gum. aslong as im driveing it evey day theres no problem.
The gas dosent stay in my tank long enogh to get real bad.

[Glenn C.]

With some models of Fordors i.e. Briggs.....the fuel tank is located under the cowl, not exposed or sitting on the top as other Model A's. If the previous owner removed the tank for whatever reason, to repair a leak, to clean inside, etc. They may have used some sort of tar soaked pad or other type of sealer between the tank and the underside of the cowl, to prevent splashed fuel, or rain water seeping around the filler connection and into the vehicle. Usually there should have been a rectangular pad of felt material, about 10"x12" with a hole cut in the center for the gas filler neck. This pad acts as a dampener between the tank and cowl. It is possible, that whatever may be installed there is melting from heat from the sun and engine, allowing that goo to seep out around the top.

[Domino]

Keith, your description of the stuff is right on target. I took a bit of rubbing alcohol as suggest by others and it wiped right off (along with a bit of the paint) but left a slight haze it the paint which hopefully I removed by washing with water.

[Bruce]

I get streaks from the gas nozzle when I try to get the tenth gallon of gas into our '29. It only happens when the tank has been filled full -- like this last weekend when we drove 499 miles in two days (a personal best!). The stuff is not as black as yours, and it does not wipe off easily. My cap has the leather gasket.
I always thought it might be melting car wax. Some more wax and a dab of elbow grease takes it off -- without damaging the paint.