Have a hairline crack at corner edge of seam (running to bottom of 200 gallon tank). Don't wish to remove tank to fix. Have emptied out diesel fuel already. Any suggestions on how to repair and what best product to use? Need reply ASAP. Thank you.
While we understand your preference to fix the fuel tank in place, we know of no safe procedure to accomplish this. Our recommendation is to remove the tank, thoroughly steam clean it to remove any diesel residue, then weld the tank, and finally reinstall it. This is a potentially dangerous job and should be done only by a competant technician who is experienced at repairing fuel tanks. DO NOT ATTEMPT TO DO THIS AT HOME!
This is one of those- 'been there, done that' things for me. For me the hardest part was emptying and refilling the tank (three times)and you have already done that.
I agree with Newells tech staff. Pull the tank and take it to a good welding shop. They can weld it in a matter of minutes (diesel tanks are easy to weld).
It is fairly easy to remove and two people can manhandle it. Be sure to flush it out after welding to get the 'burnt' residue out.
I tried the 'in frame' repair once and within a matter of months, I was seeping diesel again. You might consider having the welder reinforce (weld) the mounting plates as they seem to be a common failure point on fuel tanks.