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Leaking Fuel Tank

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397Hello Monacoers,

This is my first post on this site and I am not sure if this is the proper location for this post. My first thought was the chassis; however, I could not find anything relative to fuel. So, here I am in the general section. I have a 2002 Holiday Rambler Endeavor 38PBDD on a Roadmaster RR8R chassis and my fuel tank has developed a minor fuel leak at the left front mounting bracket location where it is welded to the tank. 

The tank is fabricated of 1/8” mild steel plate and measures 16 1/4” W x 90 1/4” L x 18 1/2” H. My plan is to remove the tank and take it to a local fabrication company to do the repairs on the tank. But, before taking that leap, I would like to learn as much as possible about the tank, the removal and installation of replacements before I start this project. Has anyone experienced a similar problem with their coach where they had to remove their fuel tank? If so, what are the procedures to follow?

I would like to have some comments on the engine pick-up supply and return lines as well as the pick-up and return lines for the generator that are mounted within the tank. Will the tank slide out with the 90-degree elbow fittings still mounted to the tank or will they have to be removed in order for the tank to be removed? Are construction drawings available on the construction of the fuel tank?

Thank you for your comments,


02 Endeavor


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I suggest you try liquid steel putty first. I have used it many times with good success. Just clean the area good with sand paper and some acetone. You can apply it it to the area even if it is damp from diesel. Just dry best you can and make sure you apply it past the damp area. Only cost about 6 bucks to try first and save lots of time.

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I don't envy you having to take it out and am no help with that process. But like klcdenver said I would try something to patch it first. Permatex makes a spray as well that might be worth looking into. I used it on an oil pan and was surprised how well it worked. I almost didn't change the pan because of it but had the new one so I did.

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Thank you, Kenneth. Your suggestion is most certainly at the top of the list of possibilities and if this was a puncture into the tank it would have been done. I believe this is something that goes all the way back to the time this tank was manufactured and it has taken this long to show itself. This area has always shown signs of a fuel leak since I bought this coach some 20 years ago. In order to determine the repair, I must first find the source of the leak and what caused it. In order to do that, I must unbolt the tank and shift it left or right a minimum of 3 inches to clear the frame that supports the tank to the chassis. Then thoroughly clean the area for inspection and possibly perform a dye penetrant test on the weld for the mounting bracket. I do not believe something has worn a pin hole into the tank; but, that could be a possibility. I just want to be prepared for my worse case scenario.


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To remove the tank by yourself is cumbersome and lengthy, but not difficult. I had mine out to have another bung welded in place.

First run the tank low as you dare and then pump out the remainder fuel.  A small electric fuel pump and two long hoses works well. Just make sure you have enough storage for the fuel. You might need 20 gallons.

I took mine out from the passenger’s side as my coach was in it carport, hmmm RVport, and that was the side available. Take a close look at the surrounding flange plates. They are screwed in place and have black silicone along the seams that mimic a welding bead. Remove this flange.

Remove the wires from the fuel sending unit. At this time it would be wise to spray all the debris off the top of the tank with an air nozzle. Use a dry paint brush to clean off the top of the fuel sending unit to preserve the label on to of it. 
Take lots of pictures from different angles. This will help reassembling. Look closely at the sending unit wires. If you can’t see the writing on the wires, just label them so you can reattach correctly. You could do same with fuel hoses, but probably not necessary.  There is a small balance  line that connects on both sides that does not have to be removed.


Once the lines and wires are done, remove the two mounting bolts, one on each side. Now that the tank is free, use a floor jack with a large piece of wood to distribute the load. I used a 2 X 6.  It has to be small enough to fit between the tank cross supports giving you enough leeway to pull the tank out. Look beneath the tank to understand the layout. Jack up the tank in the middle and with one hand on the jack handle and the other on the full tube to balance the tank, start pulling it out. Once the block of wood hits the cross support, lower the tank and reposition the jack. As a side note, before using the jack, make sure you lube the wheels and swivel bearings, and also the handle at the base. Also clean the concrete that the jack is rolling on. A tiny piece of debris will stop the jack from rolling smoothly.
Through several of these steps you will have the tank out. In my case I ran out of concrete on which to scoot the jack along.  I just added a piece of plywood.

Loading in my truck bed was a bit of a challenge for one person.  I just kept jacking up one end of the tank, and kept placing a support underneath in case it wanted to fall. I lifted it the last few inches.  PHEW!

The gas/fuel tank shop I used put 10lb of dry ice in the tank so they could weld on it without any oxygen inside.

If you have a helper with the lifting, getting it in a truck bed would certainly be easier. 

Good luck!











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That is without any doubt the best reply I have ever received! Thank you Happycarz!!! While mine is mounted a little bit differently in the coach, all of what you have stated should apply to my situation. You mentioned a "small balance line" on the tank, can you tell me anything about the tank? Does it have compartments or baffles? I am just thinking about the purpose of that small line from one side of the tank to the other side.

Again, thank you for your reply, a great one!


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Kudos to Happycarz for the great tutorial. 

I have a 2003 Endeavor and no balance line.

As long as there's no crack developing, and if you've had the leak for 20 yrs I'd say no, I would definitely go with the liquid / epoxy repair with the sanding / acetone prep.  I'm a JB Weld kinda guy but do the research and make sure what you use will handle diesel. 

Good luck,

- bob

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