1948 Cub Fuel System Troubles

[Dale Finch]

I would say just enough to wash what's in there down the drain. If you had the tank off, you could swish it around to try and get everything down to the outlet hole. Otherwise, you can use a cheap toilet bowl brush (you'll need to flatten the circle of bristles so it'll fit through the tank neck) and brush the debris toward the drain. I've also used a paint stir stick.

I've used a cork to plug the drain while I try to move things toward the drain then pull the plug all at once.
You can filter the debris out of the kerosene & reuse it as much as is necessary to flush everything out. Whatever remains, will hopefully be caught by the sediment bowl.

[markges]

Thanks Dale (and everyone else!).

[Don McCombs]

If the debris is adhering to the tank, you can use a pressure washer to loosen it. If you do that, make sure you drain it well then rinse with alcohol.That should remove any residual water. Then rinse with kerosene or diesel. Off road diesel is cheaper. If the interior of the tank is rusty, a different technique needs to be used.

[markges]

My Cub fuel saga continues. Here's the latest (with my questions):
1. The fuel tank contains a lot of debris (or rust--I'm not sure what it is) (I'm going to clean it out according to your recommendations). The tank does not look rusty. Could it be rusty on the inside ceiling? Or in the places where I can't see? Has anyone ever put a tiny camera inside a tank to look it over? If it's not rust, what is it? Is it dirt from the farm that somehow gets into the tank?
2. When I unscrewed the sediment bowl assembly (to drain the tank) I removed the fuel line to the carburetor. I think I messed up the threads to the sediment bowl assembly AND to the threads into the carburetor. I had wrench problems. It seemed that no wrench was the right size (and I have American and metric sizes). I messed with both sides of the line with my wrenches and might have overtightened the line at both ends (I loosened and tightened trying to figure out why I was having wrench issues).
3. I went ahead and removed the carburetor in order to either clean it or replace it. If I messed up the threads where the fuel line enters, it will leak fuel through those messed up threads, correct? Does this mean I need a new carburetor?
4. Has anyone ever used a fuel tank sealer? Steiner has a product called Fuel Tank Sealer made by Northern Factory, Inc. I don't know how to use it. How do I seal my tank (if I have to--I might not even need it)?

[staninlowerAL]

OEM Carb and sediment bowl are 1/2 x 20 threads. If you are not able to get it to seal when you reinstall it, both can be helicoiled. There are other options to use a brass 5/16 compression fitting but the side that screws into the carb and sediment bowl will have to be re-threaded with a 1/2 x 20 die. This allows the fuel line to connect to the brass fittings and you can seal the damaged threads with thread sealer. Send me a PM if you need more info. I've done this several times when the threads were damaged. Also, check the HOW TO subforum for tips on fuel issues.

[Urbish]

4. Has anyone ever used a fuel tank sealer? Steiner has a product called Fuel Tank Sealer made by Northern Factory, Inc. I don't know how to use it. How do I seal my tank (if I have to--I might not even need it)?

I have used a product called POR-15 on the fuel tanks for two of my old Farmalls with great success. My procedure was to FULLY drain the tank, put some soapy water or simple green or similar in it and clean all fuel residue out really good. Remove the sediment bowl and plug the outlet (tape, cork, whatever - protect the threads from intrusion of the sealer). Then I put some clean pea gravel in it and shook it around to knock off any flakes. Pour out all gravel and rinse with water. Let it fully dry, then pour in the POR-15. Rotate the tank around in all directions allowing the stuff to flow and coat ALL surfaces. Pour out excess. Once fully cured, make sure it didn't plug up your sediment bowl fitting (can drill through the thin skim of sealer if it did). Reinstall and rejoice at a rust-free tank.

I did one of mine over 10 years ago and it is still holding on just fine.

You will probably want a pint can for a Cub fuel tank:
https://por15.com/collections/fuel-tank-restoration/products/fuel-tank-sealer?variant=39607017046183

[Eugene]

I have used Red Kote to seal fuel tanks with great success. Same process Urbish described.

What ever product you purchase, use this sites search function for more information on the process.

[ParlowMillFarm]

Great timing on this post. I have the same issue with my '49. Cleaned carb twice, cleaned sediment bowl, changed gas, replaced plugs, reset timing. It's been so long without a problem I forgot about the screen inside the carb. Gotta check it out. Thanks to Glen for a detailed post on fuel issues.

[Larry in WNY]

You could add another screen on the sediment bowl. Screw the assembly into the tank a little more than flush and the brass part gives some space so you don't pick up junk. Clean it out good to get rid of the bigger pieces. The screen is from Steiner. The thread tape is gas/petroleum resistant PVC from Home Depot.
Larry

[k hutchins]

On my used '48 l bought a few years ago l installed a "tower" in tank screen in the fuel bowl. Steiner sells them. It was a little loose in the hole so l wrapped a thin strip of aluminum foil around the tip until it fit snug. I haven't had a problem since.
If you have some rust it could cause more debris in the future. Why not hedge your bets and install one while you have the bowl housing off.

[markges]

Thank you for the comments everyone. I have been out of the country for the better part of June and July. I'm finally back now and ready to work on my 1948 Cub. Urbish commented on using POR-15 to seal the tank. My question about POR-15 is: How do I coat all surfaces without removing the tank from the tractor? My tank is still connected to the tractor. Can I get a couple of friends and just jerk the tractor back and forth with our hands and muscles? Will that coat the entire tank? Maybe not?
One more question: I ended up buying a new sediment bowl assembly, fuel line, and carburetor. This is because I stripped the threads inside the old sediment bowl assemble AND the carburetor. My question is: Would anyone recommend using plumber's tape on the threads of the fuel line on both ends? Or should I just be careful to tighten everything just right, but not too tight? I'm worried about fuel leaking.

[tst]

tank has to be prepped off the tractor, use acid to eat out the rust 1st, leaving any rust and debris the por will just peel off and plug it all up, por 15 after its poured in tank needs to be sloshed around in it to coat it

[Glen]

Hi,
You would need to remove the hood and gas tank, so you can tip it all directions to coat the whole inside.

You can't see the rear part of the tank through the filler, there is a baffle in the tank.
Try to coat the rear part of the tank without seeing it, by turning it every direction.

I haven't had problems with the gas line leaking, using the original style fittings, and gas tube.
Don't tighten them too tight, the metal in the carb and strainer is soft, if the fitting goes directly in the strainer, some strainers use another fitting that the gas line fitting screws into.

Below are listings at TM Tractor.
The 1st is for the gas line for the vertical exhaust system.

http://www.tmtractor.com/new/fl/864fp.htm

The listing below shows a fitting closer up, the ring tightens on the tube the 1st time you tighten the fitting in place, and the ring breaks off of the fitting, and is tight on the tube, and the fitting with the place for the wrench will turn.
You have to position them right on the tube the 1st time, so the ring is in the right place.

I don't know if they fit the new foreign IH style carbs, or if they use a different size fitting.

http://www.tmtractor.com/new/fl/512fp.htm

[Urbish]

If you don't want to remove the tank, you'd be best to add a screen as the others have shown. POR-15 is pretty thick (like warm maple syrup) and would not slosh enough to fully coat, unless you bought 7.5 gallons of the stuff (which would cost about as much as another tractor).

[staninlowerAL]

The threads in your carb and sediment bowl assembly/fuel shutoff valve can be repaired. There's several options listed in the HOW TO subform, one is to helicoil the threads.