Gas tank leak. Got a few ?'s

[metalmonkey47]

On '76 620.

 

 

 

 

I have a steady drip that I noticed this morning from the tank at both sides towards the front on the lip. It's not a broken or disconnected line on top of the tank, or fuel filler neck (my first thought. I went ahead and replaced all the rubber hose's. Theres no cracks or holes.

 

Are there any lines on the sides behind the brackets that bolt to the lip? Also, is there any kind of seam at that lip that can potentially leak?

 

 

 

I'll get you guys a few pictures so you can see what I'm working with.

 

 

It rained all night, so I'm trying to dry things up. Its crazy hard to find the leak with water dripping off everything.

[metalmonkey47]

Also does anyone have a diagram of the tank? Fuel lines and all?

 

I have one for a '78, but it appears to be a different design.

[metalmonkey47]

also, if anyone has a picture from the top of a 620 tank, that would help me a ton.

[datzenmike]

There is a welded seam that runs around the middle and dirt collects on that lip where the tank bolts to the front and rear mounting bracket. Wet dirt = corrosion.

 

The '78 and '79 were different and they bolted to the frame not the box.

 

First attempt at a screen capture. Pretty sad.

 

[metalmonkey47]

Thanks Mike!

 

What I'm seeing now is that it doesn't appear to be a crack or any rust. The tank seems to be in good condition. Theres no obvious signs of damage, so I'm betting it's a line above where I can't see. It wasn't leaking when I picked it up, but it started leaking after I filled it up.

 

Highlighted below are the areas I've narrowed down the leak. The arrow points to where it was dripping, but after stuffing a rag where the red is highlighted and wiping the tank clean, I have no more drips so I can only assume the leak is up from there and running down hill to the lowest points.

 

 

[MicroMachinery]

My friend's 620 had the same problem. He wouldn't notice it until he filled the tank, then it was like Niagara Falls. The seam that connects the two halves had split. We ended up just getting a new tank, but if you know someone who can tig, I'd go that route, first(be sure to clean out ALL traces of fuel first.. and torque your lug nuts).

[metalmonkey47]

Gonna ignore the lug nutz right now. I'll lulz later.

 

 

I dropped the tank and I found 4 pin holes on the seam on both sides. Gonna clean it up and JB weld that mofo. They were tiny holes, but enough to piss me off. Oics when I'm lazy later

[datsunaholic]

If you have pinholes, imagine what the inside of the tank looks like. There will be many more to come.

[datzenmike]

http://jbweld.net/products/jbstik.php

 

[Z-train]

Tank needs to come out and be thuroughly douched.

[metalmonkey47]

http://jbweld.net/products/jbstik.php

 

 

^^ That's what I used. Worked great too.

 

Tank needs to come out and be thuroughly douched.

 

I'm gonna find some free time one of these days to take it to someone.

 

 

 

 

 

[Z-train]

[wayno]

What you need to do while the tank is out is go buy a good quality tank sealer, I use Bill Hirsch, it seals a tank with existing holes, and then you will never have another problem, I fixed a ford ranger tank about 20 years ago, everytime I fixed the holes, more would appear as the tank would pressurize while running, I used that tank sealer mentioned above, never had another problem. It even sealed existing rust after I used a chain to get the big chunks out.

[metalmonkey47]

Yup, so that tank patch already went to shit. I topped it off, got home, and it's dripping again. FML