Community Forums

gregk · 05-02-2011, 05:24 AM

Now I have a problem. Need suggestions from this wealth of knowledge.

The slow seep of fuel is from the weld where the threaded plug was welded into the tank. It is not from the threaded plug itself but the weld. Just a tiny hair line crack.It only drops two to three drops per day.

I hate to think about that tank having to be dropped and cleaned out so it could be rewelded. Plus I always fill up just before getting home and putting her back to bed in my building. So I have 100 gal of deisel fuel at $4.00 gal. Ouch!

Has anyone had any experience with some sort of surface sealer. I am aware of something called JB Weld but not real sure if this will be an option - I will reasearch that product. I can clean the spot to be sealed but as soon as you wipe you imediately get a small amount of fuel that reappears.

I will be very interested to see if any of you guys can provide soom suggestions. Help!!

Drifter · 05-02-2011, 05:36 AM

Most truck stops or repair shops have things like JB Weld or different types of epoxy. Here's a explanation that I found online:

"If the leak is at a failed seam without structural issues, then it's possible to seal it externally with many of the rapid-setting epoxy products. Most of them are mercaptan based epoxies, such as the JBQuik, and will bond onto clean, dry, and roughed-up steel.

I've fixed a couple of hundred tank leaks over the years with industrial grade epoxies (which are much better performing but much more expensive and not available in small quanitites, ie Belzona or CIBA industrial products), but the key to a more durable repair is to get the tank surface clean and dry for a much larger area than the actual leak. It is essential that there be no diesel fuel at the repair site, because it is a bond-breaker. Aggressively clean the site, rough it up, and clean it with solvent that leaves no residue. I use Acetone, but there's lots of spray brake cleaners that will do the job.

Use a small amount of the rapid setting epoxy to seal the leak site and let it cure, about 5-10 minutes. Do whatever it takes, press it into the seam or crack if you can find it. This is important because you later want to verify that you've got the diesel fuel leak stopped so that you can prep the adjacent area. Scuff up the epoxy surface and steel with 36 grit abrasive, wire wheels, whatever it takes to leave it clean, dry, diesel free, and rough. Build up more of the epoxy around the repair site using the regular cure, higher strength epoxy (such as JB Weld). Depending upon how large the repair site is, you may want to do this a couple more times; it helps to use a fiberglass mesh cloth laid into the epoxy to build even more strength into the patch area.

Allow to cure at least 24 hours for maximum strength. Warmer temps are better, so if you have a heat lamp, that can help. Don't get the epoxy heated over 115F, you're just trying to accelerate the cure cycle. Of course, if there's any doubt about fire safety in the area, don't use supplemental heat.

If the tank has failed structurally, so that the seam is working apart while you drive, then an external epoxy repair at the seam will not hold it together. Most of the tanks I've fixed were damaged on construction, trucking, or machinery sites where the equipment downtime was critical and the fixes were reasonably simple for a field service call. But it's reasonable to fix holed fuel tanks, damaged oil pans, and so forth with epoxy for durable repairs."

roscoesdad · 05-02-2011, 06:06 AM

JB Weld will hold it if you can get it to stick while seeping. I would try. If it won't stick, then drain the fuel and reapply. I have used it on gas fuel tanks , but the tank was empty when I applied it.

Bighammer · 05-02-2011, 07:25 AM

I had a GOOD welder repair mine last year. My tank was 3/4 full of fuel. He cleaned the road grime etc. and carefully spot welded the area being careful not to get the tank to hot. After several spot welds the leak stopped. He then used an epoxy sealer (JB WELD) over the spot welds. It is holding up very well after 7,500 miles.

JManatee · 05-02-2011, 07:01 PM

Quote:

Originally Posted by Bighammer

I had a GOOD welder repair mine last year. My tank was 3/4 full of fuel. He cleaned the road grime etc. and carefully spot welded the area being careful not to get the tank to hot. After several spot welds the leak stopped. He then used an epoxy sealer (JB WELD) over the spot welds. It is holding up very well after 7,500 miles.

Are you saying he welded on a tank with fuel in it? You should NEVER attempt that. Quick way to die!

JMHO

powerboatr · 05-02-2011, 07:41 PM

Quote:

Originally Posted by JManatee

Are you saying he welded on a tank with fuel in it? You should NEVER attempt that. Quick way to die!

JMHO

not true
we welded fuel tanks with full gas and diesel.
with little dripping flames.
the vapors will get you, if it empty or the flame gets above the liquid line.
if the tank is full, a good welder should be able to dispatch your leak in a jiffy

your tank inst going to explode because a flame or arc welder is doing a small crack. but the normal disclaimer applies.....
have a certificated welder look at it and then go from there.

Oh-one · 05-02-2011, 07:49 PM

Could you drive out as much fuel as possible and then either jack up one side or park on a slope to dry out the leak? Then apply the epoxy to a clean surface.

ulric · 05-02-2011, 08:11 PM

I think you are going to have to take it to an expert.

If it were truly a small pinhole defect it might be possible to stop it temporarily by blowing some kind of hardening substance such as epoxy, superglue, JBweld or Seal-All backwards into it with something like a hypodermic such as is used for windshield repair.

You might also be able to go outside the area that gets wet with fuel and get a clean enough surface to build up a JB Weld type of repair, but either type of repair would merely postpone the inevitable, which is proper repair by a qualified tank repair service.

If it is a crack and not a pinhole, cracks tend to travel, so the leak will probably get bigger.

If you could put enough of a vacuum on the tank to reverse the fuel flow from the crack and suck air into the tank through the crack without collapsing the tank, you could suck a little MEK through it to clean the crack surface and then try sucking epoxy in. You should build a vacuum release to keep the vacuum at a point lower than needed to collapse the tank but high enough to suck air through the crack. Hook up a vacuum guage and then turn on the shop vac to create vacuum, then adjust with a gate or ball valve so that the vac won't be too great. Be careful; not to suck fuel into the shop vac, and be aware of the hazards of fuel vapors and electric sparks if your shop vac motor is not sealed off from the impeller.

In short, the BEST thing to do would be to take it to an expert.

HoRotica · 05-02-2011, 08:31 PM

Pig Putty.

Every RVer should have a tube or 3 in their coach. I have patched an aluminum oil pan on a race car that got cracked and had synthetic Royal Purple 0 weight oil dripping out of it with pig putty without having to drain it.

Have seen it work on gas tanks while gas was running out of it.

Get you some! Scuff the area up kneed the putty to a uniform color and apply. Its that easy... Wet your finger to smooth if your worried about appearance.

Chris

www.newpig.com

FleetMan · 05-02-2011, 08:33 PM

Shade tree fix, kinda out of school thing but when I was in Vietnam, aircrraft maintenance, we had an F-4 with a fuel leak in one of the wing tanks, wet wing configuration and had to get it back in commission ASAP. We dried the exterior as well as we could and used automotive Bondo on it to seal the leak. It held like a champ and had to be ground off to do a 'regulation" repair at the next major inspection. ulric's suggestion using vacuum to help dry the area is a good idea, it works when installing a Fumoto oil drain valve with a pan full of oil.

mfire1339 · 05-02-2011, 08:43 PM

I would try to "peen" the hole shut. Done it a couple times.

Mike

KIX · 05-02-2011, 08:44 PM

The tank can be welded while full of diesel...........no problem. Just do short welds so the fuel inside doesn't get too hot.
Another temp fix would be to peen the leak spot in the weld you described in the OP. But, welding would be your best bet for a long term repair.

moisheh · 05-02-2011, 09:27 PM

Years ago welders indeed did weld on full tanks. Law suits prevent anyone from taking that chance if he or she has some smarts. I would try and rent a pump and some barrels to store the fuel. Then you could remove the tank and take it to a shop to be repaired. Some rad shops offer that complete service.

Bighammer · 05-02-2011, 09:31 PM

Quote:

Originally Posted by JManatee

Are you saying he welded on a tank with fuel in it? You should NEVER attempt that. Quick way to die!

JMHO

Use the search function and you will see this is a fairly common problem with the 08 fuel drain bung. Also you will see many people had it repaired as I did by welding with fuel in the tank. As one of the other posters mentioned, do short welds so as not to get the spot to hot. My leak was much more severe than the OP mentions. "Good Welder" are the key words. Cost was $100.00, or you can take the tank down etc. etc. etc.