Leaking Fuel Tank Vent

[Bolt]

I have a leak coming off my fuel tank when it's completely full to the top, like if I fill it up with 31 gallons of diesel. I dropped the tank partially the other day and found it to be leaking near the vent fitting under the cab. I put some hose clamps on the barbs because I figured that's where the problem was coming from, not the the vent itself, but I think I was wrong, because it's leaking again. So it's coming from the vent fitting I suppose. I did the harpoon mod a long time ago and this is the first time it's been leaking on me.

Has anybody else had this kind of leak? How did you remedy it? Put in a different vent with longer hose and mounted higher up? Where did you mount it, and what kind of vent did you use?

 

[Zmann ARGH]

I can send you a pic of a ccsb tank if it will help but I think you may need to extend the vent up higher ,, I did a replacment midship tank and harpooned it .. I have my vent runnning up past the fuel filler door

 

[Bolt]

Did you just use the factory vent just on a longer hose? Do you happen to know if it was 7/16" or 1/2" hose?

 

[Zmann ARGH]

the factory on the stock doesn't run very far ,, and it vents between 2 locations ,, it also has anti drain check valves in the tank fitting ,, my aftermarket was a bit different ,, but in your case I think that u need to just extend the one common vent line up higher //you are basically so full ( harpoon) that any expansion has no where to go

 

[Bolt]

Okay, so there's a check valve in the elbows that go into the tank? is one of those maybe leaking on me and causing the leak that wasn't there the first while I was harpooned?

What part of this is the roll-over prevention portion of the vent, the check in the tank fittings in conjunction with the vent tee on top of the tank?

 

[Zmann ARGH]

the tank fittings for the vent are check valved in case of roll over ,, then if I remember correctly the run together via frame mounted lines and then the final vent to atmosphere is just sitting close to the top of the tank //if you are getting the tank to full it would drip out the end of the vent ,, my new tank did this before I extended them up higher .. basically if fuel is going up the filler tube at the full level .. it will find it's way out the vent ,, so thats why I raised mine above the fuel kneck

 

[Bolt]

Yeah I understand the concept just didn't know where the checks in the system were. My vent is under the cab, teed to the fitting on the tank near the front and then a hose goes along the frame to the rear vent. The actual location of the vent is quite low, I bet even stock it would get fuel up above it, so something started leaking just recently because I've been harpooned for years already. But I will move it up higher, above bed floor height or so. Anybody know of a better vent to replace it with? I've googled plenty of vents but can't find much to suit me.