gas leak

[r.booser]

Picked up an 85 c20. Fixed the motor issues an take to the gas station for a fillup. Part way thru I notice a leak. Looked down an where the filler neck connects to the tank gas was coming out. Looks like some idiot put silicone all over the where it connects. So obviously this was an issue before. Can I just replace the neck? Or do I need to get a tank an filler neck?

 

[junkyardog05]

Picked up an 85 c20. Fixed the motor issues an take to the gas station for a fillup. Part way thru I notice a leak. Looked down an where the filler neck connects to the tank gas was coming out. Looks like some idiot put silicone all over the where it connects. So obviously this was an issue before. Can I just replace the neck? Or do I need to get a tank an filler neck?

If there isn't a hole in the tank then just replace the filler neck.

 

[r.booser]

Ok I'll rip all the silicone off an take a look. Are they pretty easy to replace?

 

[junkyardog05]

Ok I'll rip all the silicone off an take a look. Are they pretty easy to replace?

Not to bad to replace, you can split the hose if its bad comes off easy. Putting it back on is a bit harder heating the new filler neck to make the rubber softer will help.

 

[r.booser]

Ok thanks. Gonna get that an a hearer core tomorrow

 

[marks86]

kind of irrelevant but I had a truck one time that the vent was clogged and it used to leak fuel from the top of the filler neck and out the fuel door

 

[r.booser]

It's not the top. It's where it connects to the tank. Covered in silicone, duct tape probably would have worked better...haha

 

[chengny]

The best way to do this job is to remove the hoses at the tank (leave the other ends attached to the fill neck), detach the fill neck and mounting plate from the fender, and then bring the whole assembly out. Also release the bolt for the grounding strap.

Put it aside and inspect the tank nipples. Clean and repair them as necessary. Inspect the ends of both hoses inside and out. Replace/repair as needed.

Get two new stainless steel hose clamps. Apply some Vaseline to the tank nipples, install the hoses, tighten and remount the fill pipe to the fender.

Some visuals:

You must be registered for see images attach

 

[r.booser]

Thanks, doesn't look to hard

 

[chengny]

The hard part will be getting the clamps off.

It's probably going turn out to be an improper previous installation of the hose clamp - to far up the hose. Or maybe just a broken hose clamp.

If either of those is the case, disregard all the steps described above. They won't be necessary, just relocate/renew the clamp.

WEAR SOME EYE PROTECTION - there will be a lot of rust and scale falling into your face.

 

[r.booser]

Do clamps come with the new hose or will I need to get those seperate? With the previous owner...nothing would surprise me

 

[chengny]

New hose? Who said anything about a new hose?

Your hose will probably be alright. It's made out of heavy duty reinforced rubber and never sees any heat, abrasion or vibration.

I didn't want to bum you out before but, what you should be most worried about is finding that the problem is with the steel neck/nipple that extends out from the tank. The hose slips over it and the clamp seals the two together.

What can happen is, the steel nipple gets rusty. The rust eats away until it is weak and finally collapses inward. At that point, the seal with the hose is lost. Then when filling up - as gas flows down the pipe it hits the opening in the neck and leaks out.

Just pull the clamp and yank the hose off the neck. Then you will know what you are up against.

If it is a clamp failure, go to Home Depot, buy a clamp and put it on. Done.

Wasted steel in the neck....come back here.. I have some tricks to save money.

 

[r.booser]

It was leaking for like 30 minutes or more after I got gas. I'll rip all the silicone off tomorrow and check. So your saying there is a clamp that goes where the filler neck goes into the tank?

 

[chengny]

No, don't think I said that. Anyway:

The basic tank configuration is common to several different styles of vehicles, but the direction that the connected hoses approach the tank from, will vary. All depends on which of the various body styles the tank is to be mounted under.

The tanks come from the mill as blanks (without any nipples to connect the hoses to). Then, according to the production requirements of the assembly plants, the correct nipples are attached. Which type of nipple that goes on the tank is specifically made for the type of vehicle being assembled.

This final step in the tank construction - adding the fill and vent nozzles - is accomplished by a soldering process. A silver solder ring is placed over the appropriate tank opening the nipple is slipped through it (actually enough so the pipe protrudes slightly into the tank interior). Heat is applied and that is it - it gets a sender and it gets strapped into the frame.

That brings up another very possible cause of your leak; The solder joint has failed and the gas is leaking out at the interface of the fill neck and the tank wall.

But like all the other stated possible causes, we won't know for sure until you actually go out and get under the truck. Dude, it only takes, maybe 5 minutes to do this investigation.

Go out to the truck and release the clamp by backing off on the worm screw. Then pry the hose end from the fill neck with a screw driver (you can even use the same screw driver that you used for the clamp).

When that is done, I assure you, you will know what the problem is. You will then be be prepared to take the appropriate repair steps without guessing.

You want to know how I would deal with this situation. Ignore it.

Unless by some freak chance it was noticed at a state vehicle inspection (and I was told to fix the leak), it would very, very likely stay that way forever. I would just adapt and learn - learn to stop pumping gas into the tank before the level reached the leak.


Here are the construction details of a truck with a typical pickup body. It looks like this:

 

[Stroked]

Are you saying it's leaking where the actual metal filler neck is attached to the tank? If so, you probably have a rust problem that will be harder to fix. You might be looking at a new tank if so.