Leaky W108 Gas Tank

[alant912]

My gas tank in my 1970 280se is leaking from the front center gas tank seam. It's a small drip that occurs when it's parked down-hill or the tank is filled.

Any suggestions for how to re-seal it?

[Tomguy]

You'll need to identify the cause of the leak. For example, is it rust? Or damage? I've never heard of a seam seal going bad on one of these tanks in the 15+ years I've been on this forum, so it's probably caused by something.

If it's rust, you may need to get a "New" tank. These can be hard to find in good condition. If it's damage, a shop should be able to correct the damage. While the tank is out, it may be a great time to have the inside cleaned and a coating applied to prevent internal rust-through from hygroscopic Ethanol gas.

I would advise against a temporary repair for anything more than the time it takes to get the issue corrected, be it a new tank or repair of your existing, since as the name implies, it's temporary, and you never know when or where that patch may fail. Maybe your luck is better than mine, but for me, it'd be in the middle of the night, 100 miles from anything, as I park over an un-extinguished cigarette.

[alant912]

Originally Posted by Tomguy

You'll need to identify the cause of the leak. For example, is it rust? Or damage? I've never heard of a seam seal going bad on one of these tanks in the 15+ years I've been on this forum, so it's probably caused by something.

If it's rust, you may need to get a "New" tank. These can be hard to find in good condition. If it's damage, a shop should be able to correct the damage. While the tank is out, it may be a great time to have the inside cleaned and a coating applied to prevent internal rust-through from hygroscopic Ethanol gas.

I would advise against a temporary repair for anything more than the time it takes to get the issue corrected, be it a new tank or repair of your existing, since as the name implies, it's temporary, and you never know when or where that patch may fail. Maybe your luck is better than mine, but for me, it'd be in the middle of the night, 100 miles from anything, as I park over an un-extinguished cigarette.

Thanks Tom,

It appears to be leaking from the seam at the front middle of the tank right where it bolts to the frame. Could be rust as I'm seeing quite a bit in my filter. I'll pull the tank and find out for sure.

[alant912]

Originally Posted by alant912

Thanks Tom,

It appears to be leaking from the seam at the front middle of the tank right where it bolts to the frame. Could be rust as I'm seeing quite a bit in my filter. I'll pull the tank and find out for sure.

You were right Tom. Wasn't leaking from the seam. There was a crack on the top of the tank between the fuel sender and the front seam.

[Tomguy]

Make sure you vapor recovery isn't blocked. Sounds like possible overpressure cracked it, unless you see physical damage from an impact / road debris.