The Stovebolt Site Forums The Shop Area Engine Shop Questions about re-installing fuel tank & fuel lines

I'm going to be re-installing my fuel tank with a new sending unit and fuel lines and am wondering what I should use to seal the screws that hold the sending unit in, the sending unit gasket, and whether I should use anything on the threads at the bottom of the tank where the valve screws on. I was thinking of using teflon tape on any threads. I don't want to have to do this twice!

Any help appreciated. Thanks.

Dave, people here will tell you to be leery of using teflon tape on the threads for fear of pieces coming off and clogging your pump. I found a Permatex product that can be used with threaded fuel fittings and used it successfully when installing the brass fitting at the tank.

Dave, I've had a good outcome using Gasgacinch on the screws and cork gasket of the sender and teflon tape on pipe threads. To keep teflon tape from getting into the fuel system a couple of bare threads can be left on the small end of the male part so that the teflon won't be cut by the threads and fall into the tank.

My '71 Dodge van has a later year 36 gallon tank on it and the sender is located on the front of the tank, not the top. That's the true test of whether there are leaks. Cork is a low tech gasket material but it sure seems to work in that application. Cork also works great on steel sandwich valve cover gaskets and intake manifold front and back ends that seal against V8 blocks. Good stuff!

There is also a Permatex anaerobic sealer that is not designed for gasoline applications but works perfectly in that application. I used it on the float bowl cover paper gasket on my '36 Chevy pickup that was a chronic leaker. That may be what Eureka Jim is referring to.

You don't need anything on any of those places. The factory used nothing. The gasket seals. The pipe threads seal. Any flare fittings will seal.
It's a must to know which of your trucks you are talking about when you post any question. 1950 or 1963.

Bartamos- I'm talking about the '50 truck. The flare fittings I will install of course without any additional product, but I'm very leery of putting a tank in the cab without anything on the screws... these days I have to wonder whether the replacement screws are as well made as the ones that the tank came with- they may not be.

Jim & Ray- thanks for the info. I like using cork when I can find it.

I installed a tank in our '63 and I swear the thing is venting through the screws. I did not put anything on them.

Dave, the standard 5 screw sender flange has a rubber gasket. This gasket is very adequate. It's only splash "pressure". It won't leak. The screws won't leak.
If I had a AD, I would use/modify a TF sender/pickup. They draw from the top. So do 60-66. Plug the tank at bottom with pipe plugs, no valve. The 59 motor you have in the 50 has a fuel pump designed to draw from a top outlet sender. So no worries there. These say they work with your tank. 49-53 and 54-59 ??? check it out
Have not read on here that anyone has used this on 49-53. But the web says it works. This style avoids leaks in cab.

Thanks Bartamos- I'll research the top draw further.

Dave

I have a top loading fuel sending unit on a 49-53 tank with the rubber gasket and it works. The holes in the gasket are smaller in diameter than the screws, providing a good seal. Mine did not leak even with the extreme tank pressure caused by the stupid aftermarket non-vented gas caps.
If you can't get your tank to seal with the rubber gasket, you need to look closer at the surfaces which you are trying seal.

Ok, I am now armed with a lot of info here. I'll try to rubber gasket first.

Thanks again

I have had trouble with vented caps also. Now I drill a 3/32 hole in the cap.

3/32" would be better than 1/8" in most cases for me since I can never seem to be able to find my 1/8" bit.
Would 5/64" work, or would that be too small?

5/32 is bigger than an 1/8.

Yeah, I just tested the new cap that I got and I can suck air through it from the inside, but it will not vent out the other way...so hot days will cause a pressure build up in the tank. I expect that this could be bad for the fuel pump diaphragm and possibly forcing fuel beyond the carb float needle, and creating leaks/smells? Anyway, are you drilling a hole in the valve inside the cap, or actually in the cap itself?

Another full system question:

I am going to make my own 5/16 hard lines going from the flex line at the tank to the fuel pump- I usually have a flexible line at the pump end as well for engine movement, but the truck didn't have one when I got it- the hard line went straight to the pump. Is this the way the truck fuel line is supposed to be plumbed?

Thanks for the tips guys.

1950 truck?

I think there was only one flex fuel line - at the tank.

Yes Tim, the '50 truck. Thank you

Reread my post. It clearly reads "5/64"...???

It says 5/64 After the edit.

Dave. The hole goes inside the sealing gasket perimeter. Just drill thru the cap where it will let air pass out of tank but not damage any valves, seals or other cap feature.

It is probably best to have rubber hose between tank/body and metal line that is hard mounted to frame. There is some movement between body and frame. Likewise at other end up to pump. There is movement between motor and frame.

The hole could be small, as Carl says, as long as it doesn't whistle like a tea kettle
Glad Carl confirmed that the top draw works. Other AD's will be interested in that. I was worried that since the 5 hole is not symmetrical and is "clocked", that that might cause the outlet to be aimed wrong and/or the pickup/float to hit side of tank.