Fuel tank leak

[Gonzalo]

My 2005 Monaco Windsor has a leak under the fuel tank after i drive it for few hours contact a local mechanic, he said id leaking by the seams any ideas  .

[Dwight Lindsey]

Mine was leaking at the weld around the drain plug.  I pumped the diesel out into a 50 gallon barrel, pulled the tank, washed it out with soap and water and took it to a welder.  The soap and water (drain and fill several times) was to prevent any possibility of diesel catching fire from the welding.

A floor jack helped me get it out by myself. 

When the welding was complete, I filled with water and watched carefully for a leak.

Not actually a terrible job.  I was quoted $1,500 by a local shop to do it, which seemed like more than I wanted to spend on it.  I bought a drill powered pump, and a $50 gallon barrel.  Welding cost me $29 bucks.  It was a long time ago, but I'll bet I spent less than $100.  Total time invested, including sourcing barrel and driving to the welder, was about 6 hours.

If yours is leaking elsewhere, you may need more welding.

First thing is to get the tank out.  I'd fill it with water when up on blocks and look carefully for leaks.

Dwight

[Doug Hoegh]

Like Dwight, mine was also leaking at the drain plug bung.  We drained the tank and used a steady stream of shop air blowing through the fill neck welding in place. 

Edited November 22, 2022 by Doug Hoegh

[dl_racing427]

3 hours ago, Doug Hoegh said:

Like Dwight, mine was also leaking at the drain plug bung.  We drained the tank and used a steady stream of shop air blowing through the fill neck welding in place. 

Even better than shop air would be to purge the tank with argon, nitrogen, CO2 or most any other inert gas.
Displace the oxygen and it can't ignite.

A while back I used my plasma cutter to cut the head off and cut vent holes around the bottom of a burn barrel.
It was one I'd used previously for diesel.  I just removed the bungs so the pressure could escape and started cutting.
The vapors ignited and it chuffed a few times, but nothing major. LOL

Edited November 22, 2022 by dl_racing427

[Doug Hoegh]

21 minutes ago, dl_racing427 said:

Even better than shop air would be to purge the tank with argon, nitrogen, CO2 or most any other inert gas.
Displace the oxygen and it can't ignite.

A while back I used my plasma cutter to cut the head off and cut vent holes around the bottom of a burn barrel.
It was one I'd used previously for diesel.  I just removed the bungs so the pressure could escape and started cutting.
The vapors ignited and it chuffed a few times, but nothing major. LOL

Totally agree.  We were careful not to let the weld get too hot, but Nitrogen would have been a whole lot safer.  50 years ago in the service we would throw our cigarette butts in the open diesel fuel bladders and think nothing of it.  Bit I was a whole lot younger and probably a bit crazy at the time.  

[DavidL]

you weld with the water in the tank. so no vapor to ignite.  Certainly not touching the weld point so you can get some heat into the weld.

Edited December 2, 2022 by DavidL

[Gonzalo]

thanks we fix it 

[Happycarz]

I removed my tank to have a bung welded in the top of it.  The same shop that I used in 1974 was still in business, now run by the son, put dry ice in the tank to displace the air.  I thought he said 10#, and he used the fill tube.

Just another option.

 

 

[96 EVO]

Harry, is the inner panels of your bay doors at your fuel tank black?

Wondering if I may have a fuel tank leak. Tank never appears to be wet.

Edited December 4, 2022 by 96 EVO

[Happycarz]

One is blacker than the other.  Diesel will get on the door regardless of what I do.  No problem, I’ll just use some Brakleen to clean them up.  The plastic does not like Brakleen. Marred for life!  I used Simple Green on the other door. It looked good….for about six months.  I just spray and wipe periodically. Works for me.

[96 EVO]

So, where is that coming from? Leaking cap gaskets?

I wonder if a little fuel could shoot out the hole in the caps for the restraint chains 🤔?

Edited December 4, 2022 by 96 EVO

[Happycarz]

When my coach was new my fill tubes wouldn’t seal and seeped constantly. I found the tapered threads on the neck and cap got tight before the neck contacted the gasket. I bought Danco brand gaskets to use in conjunction with the OE gaskets to solve the problem. I bought a bunch as giveaways to the folks at our Quartzsite gathering . 

Hmmm, these still show up in the iPad app, but not the web version. Now the price has doubled, too.

 

[96 EVO]

So, you think the mess on the inner door panels is coming from somewhere other than the caps?

[Happycarz]

I would think it is coming from the fill caps, like mine was. Is the underneath side of the neck wet, along with a wet trail down the fuel tank?

[96 EVO]

I'll check it next time I fill it and go for a run. Snow on the roads now 😞!