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Fuel tank leak

I have developed a fuel leak that drips from a point about a foot inside the drivers side directly below the tank.  Anyone have any ideas on this? It started a while back but doesn't seem to be getting any worse. I was parked full time in Tyler Texas through the winter of 16/17 and temp dropped into the low 20's a couple of times.  On those occasions I heard a noise that sounded like someone hitting the tank with a rubber mallet, I assumed it was caused by cold contraction of the air since I didn't have but about half a tank of fuel.  Wondering if I might have popped a weld.

Jack and Dianna Hunt
Coach #663
2003 - 45' triple slide

Probably just pure luck, but a repair shop put a jack under my fuel tank that left a leak. It wasn't pouring out, but if I wiped it off diesel immediately reappeared. I tried JB Weld on it thinking there was no way it would bond, but never leaked again.

Jon & Chris Everton
1986 40' Dog House #86
450 hp ISM 5 spd ZF Ecomat 2
2004 Range Rover L322 Toad

Look at the bottom of your tank there should a sump on one end with a petcock or other type of valve on the bottom. This sump is where water can collect and be drained off from the petcock.
Is the petcock leaking? Or around this area?

Forest & Cindy Olivier
1987 log cabin
2011 Roadtrek C210P
PO 1999 Foretravel 36'
1998 Newell 45' #486 

1993 Newell 39' #337 

I have used fiber glass shower repair kit successfully on aluminum diesel fuel tanks.

Thanks for the responses, I thought about JB Weld but didn't know if being soaked with diesel would keep it from adhering.  I saw the petcock under there but didn't see anything dripping from it although that doesn't mean it isn't leaking, I will check it. As for the fiberglass repair kit, that hadn't even crossed my mind.  If it isn't the petcock, I think finding the leak is going to be enough of a hassle much less having to potentially pull the tank to fix it.

Jack and Dianna Hunt
Coach #663
2003 - 45' triple slide

i would guess the pitcock is a much more likely culprit than a leak in the tank itself. i would sure start there. i always use some kind of paper product to find dripping leaks. like the blue shop papertowells or anything similar. any moisture on them shows up very clearly.


2002 45'8" Newell Coach 608  Series 60 DDEC4/Allison World 6 Speed HD4000MH


Although the leak did not appear to be coming from the petcock I decided to follow the suggestions above (and the always prudent KISS theory) so I opened and then snugged down the petcock, placed some heavy paper towels under it and gave it a few days.  Towels came back with only one or 2 drops on them which I'm sure were just residual, so apparently the problem is solved.  Again, thanks for the help everyone.  Hopefully some day I can make a suggestion that helps someone.

Jack and Dianna Hunt
Coach #663
2003 - 45' triple slide

Noticed a wet spot on the pad at home and then at the track, the grass was oily, and several other places we've stopped for a day or so.  Removed the stainless cover and      .  Sure enough the tank has rusted enough that fuel is coming out, bummer!  Decided against JB weld or any other patch.  Started removing      which wasn't difficult at all.  It's a little tight on the studs spot welded that hold the parallelogram door mechanism.  (that's my name for the door mechanism) , i had to cut a little off of them for clearance. Once out, I noticed the barrier between the battery compartment was rusted at the bottom.  Finished up the side walls with rust encapsulator and prepared to add a piece to the rusted out area.      .  After the applications had dried, added a piece of HDPE to replaced the original plywood      .  Once the tank was out, I took some measurements, removed the suction tubes, and was impressed by the size      .  The suction tubes extend nearly to the bottom (both Aqua-Hot & generator) however the main engine suction extends into the sump/sediment tank which is about 3 gallons.  

Commissioned a friend to build a new tank from aluminum, pictures follow

Coated the bottom with a substance similar to bed liner and zinc chromate to the rest. added the suction fittings and fuel gauge.  I made the tank 3/4" shorter than the original to aid in installing (the fill neck was a tight fit upon removal).  However I discovered the tanK gauge sender was too tall so, I had to turn out a spacer.

Reinstalling was easy, it was the door that took all day.  the tank capacity is 268 gallons now.  I figured when the generator runs out of fuel, you've 30 gallons left.  there is a low fuel float switch that activates about the same time.

Quite a project but fun anyway.  Without labor, cost was about $4,500.

Gordon Jones

Very nice! What did you do with the old tank? It would make a great aux tank for a pick up if you patch it.

Wow, what a project!

Richard and Rhonda Entrekin
99 Newell, 512
Subaru Outback Toad
Inverness, FL (when we're home Cool )

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