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gas tank shut-off valve

old blue

old blue

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I know, I know...alot of posts this morning!! just finished insulating the cab of my 50 3100 and re-installed the gas tank and have a leak there that can't quite fix. Shut-off valve at the tank looks to be old/original?? Will a new ball valve work here...the one that opens with a quarter turn? what do you guys recommend on thhe threads to stop leaks...regular plumbers tape?

Chuck
 
Chuck-

Is it leaking from the valve or the threads? Are the threads OK? Teflon thread sealing tape will help quite a bit, but isn't a cure-all.

The nipple coming from the tank has National Pipe Threads. The metal fuel line has flared fittings. Usually, if you get a valve from the hardware store, it has pipe threads on both ends, so you may need some adapters to get everything connected.

What I did was to remove the old valve and metal line and install rubber fuel line up to the fuel pump. The rubber line fit very snugly over the nipple, and I clamped it down. No valve to mess with. I know I can't turn the flow of fuel off, but you can't on most vehicles anyway.
 
Chuck -

I'm working the same area on my '49 GMC. I was getting a good bit of rust particles trapped in my fuel filter so I drained the tank to see what kind of shape it was in on the inside. When I put it back together I replaced the old fuel shutoff valve on the end of the nipple coming out of the tank with a combo fuel shutoff valve and sediment bowl. on the "out" side of the sediment bowl I ran about four inches of 5/16 rubber fuel line to a NAPA 3002 in-line fuel filter and then another 10" of rubber fuel line to the metal fuel line. Got it all put together and it looked real slick. Poured in a gallon of fuel and discovered the shutoff valve on the fuel sediment bowl had a bad seat and leaked badly. RATS!! The combo fuel shutoff and sediment bowl went back to Carquest and I'm waiting for a replacement... hopefully tomorrow.

Mike
 
As mentioned the threads are different , Weatherhead used to make these shut off valves if you can find a FLAPS with the big Weatherhead catalog . maybe they have a website ? .

If it's leaking from the packing nut you might be able to put in some string packing to staunch the leak , Teflon tape (just a little bit)
on the male threads into the tank will stop that part if it drips...

-Nate
 
I don't have personal experience, but was told the regular plumber's teflon tape will not give satisfactory performance. I was told to use the yellow teflon tape that is specifically made for use with gasoline and petroleum products. I found mine at Home Depot... a bit pricy at $5 for a single regular size roll.
 
Chuck -

Since I'm working in the same area I hope you don't mind if I hitch hike on your thread...

I have a lot of rust in my tank and I'm replacing the shutoff valve with a combo shutoff valve and sediment bowl in hopes of trapping some of the larger rust particles before they get to my inline fuel filter. Another "fix" I'm considering is cutting about a half inch of additional threads on the pipe nipple that connects to the bottom of the tank and then running the pipe nipple about a half inch up into the inside of the tank. That would leave about a half inch of unusable/trapped fuel in the tank, but should also cut down on the rust particles entering the fuel line. Would appreciate any thoughts out there on this idea. Would I end up with a half inch of trapped water at the bottom of my tank?
 
Mike-

I won't say that it won't work, but here's a couple of things I see. First, since the gasoline sloshes around in the tank, it will keep the rust particles in suspension, letting them get sucked in anyway. Also, the threads on the nipple and the tank are National Pipe Threads. It isn't evident on small pieces, but look at a larger pipe nipple. The threads taper to help them seal. The diameter starts narrow at the end, and gradually gets bigger, so adding extra threads might be tricky.

I would think that the sediment bowl on the valve and the extra inline filter would help out greatly. You may have to change them quite a bit at first, but the more you drive it, the less rust there will be in the tank.
 
Tim -

I understand the taper on the NPT threads. My thinking was that I'd run a die on the nipple to get an extra half inch of threads and that would make a long run of the narrow threads at the end of the nipple with the taper running from the mid point of the threads to the stop point higher on the nipple. In fact, I did it and it seemed to work fine... but, I just wasn't comfortable with the idea of a bunch of trapped water at the bottom of my tank so I took it out and went back with the standard 2½" nipple. FWIW, the 2nd combo fuel shutoff valve and sediment bowl leaked internally at the shutoff valve, but not as bad as the first... drip-drip-drip as opposed to a steady stream on the 1st shutoff valve. Decided I'd just live with it since it's an internal leak and I'll just slide a pan under the truck when I clean out the sediment bowl or change the inline filter. PITA !! And a "Made in U.S.A" part too.

Thanks for sharing your thoughts!!
 
Got the fuel sediment bowl installed below the tank. If the picture doesn't attach here you can the installation at:

http://public.fotki.com/ltcmikem/ltcmikem/49_gmc_150.html
 
Mike , that's very clever ~ thanx for the pic ~ I hope you think about adding a stone shield as the glass bowl is unprotected...

I see your cab bottom is like mine , no paint ! :P

The internally extended nipple idea would have worked quite well at stopping the rust particles , it used to be normal the solder the fuel pickup tubes into place sticking 1/2" up inside like that but you're correct the water and rust particles collect and tend to rot out the entire bottom of the fuel tank .

De-rusting your tank is easy : go to Lowe's , Home Depot etc. and buy some " Jasco Metal Etch " , it's in the flooring section , a gallon (comes in Qt. bottles) will do , now remove the fuel gauge sender and plug that hole , pour in a package or two of BB's from the sporting goods store then the Jasco and cap the filler off , and begin shaking it ~ you'll see it fizzing away in there , let it soak all day and shake it from time to time , the Jasco _cannot_ damage the tank , after it's all shiny clean inside (look with a flashlight) pour it all out and shake the BB's out , rinse with a gallon or two of fresh gasoline , straining it through some felt or velvet (thrift store) untill it comes out clean . that's it ! no more clogged filters etc.

Warning : DO NOT use Muriatic Acid ! that _WILL_ eat the good metal as well as the rust ! .

Btw : got any old crappy refrigerator magnets ? break the small round magnet out and drop it into the glass filter bowl for a BIG surprise
~ it'll grab all the tiny micronic sized rust flakes that go right through any filter and are too light to settle out by themselves .


I hope this helps....

-Nate
 
Nate -

Great suggestions! I especially like the magnet idea in the sediment bowl. On the Jasco Metal Etch, would you leave it the clean, bright steel or would you coat the inside of the tank with one of the gas tank sealer products that are on the market? I have given some thought to the glass sediment bowl being exposed to road debris... it is somewhat protected in that it sits above a part of the frame and it would take a pretty lucky bounce for a rock to take it out. Will continue thinking on that. Next BBQ is a week from today... plenty of parking room for your bolt!
 
This is a bit off topic... I'm not a computer guru, but manage pretty well with the basics. I've seen pictures posted in these threads, but all the pictures I take have too many Kbytes to meet the forum posting restrictions. How do you compress or pare down the size of a photo to meet the restriction?
 
hey guys,
update on my repair...couldn't find the right parts to replace my shut-off valve so I decided to try the yellow teflon tape as the only place leaking was from my new tank...put a gallon of gas in and no leak!!

Chuck
 
RE: gas tank De Rusting

The Jasco is merely diluted Phosphoric Acid so it will leave a flash coating of Phosphorus to help retard new corrosion , buying a tank lining kit is the best idea but I use my truck in daily service so it's usually ful of fuel and doesn't rust..

I've done some severely rusted tanks where i had to drain , strain and re-use the Jasco or get some more and swish that around a while before all the rust was gone , you might see some pits but it should be shiny metal even in the pits else it needs more soak time , any black or brown is _RUST_ just waiting for you to stop so it can come back as rust never sleeps....

I am told the dairy supply stores sell it as " Milke Stone Remover " for cleaning out dairy tanks and also school or chemical supply places
sell Phosphoric Acid quite cheaply too .

Best of all you can keep it it a large platstic jug and re-uae it to de-rust the worst rusty old bolts & nuts , metal pieces etc. it'll clean up old rusted chromed bits too but NO aluminum or brass etc. !


-Nate
 
Chuck -

That's great!! Isn't it a great feeling to get a leak stopped... and at the cost of gas today I want every drop of mine making it to the carb.
 
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