October 12, 2015

Fuel Tank Repair or Replace?

I noticed some fluid from the back of my car in late August of 2015. A quick wiff and I discovered it was diesel fuel. DANG! This is the summer of front end repair, new starter and now a leak in my fuel line.

A few days later I decided to take a quick look and the fuel was leaking from where the folks who did the conversion from gas to diesel took the fuel pump out. There was a extra filter and an adaptor. EASY - WRONG! It looked like the fuel was coming from the top of the tank and dripping down. It could be the rubber hose but I decided to remove the tank and make sure.

Here is what I did:
  1. Run my truck to almost empty.
  2. Disconnect my battery (no power, no sparks, no boom)
  3. Removed the rear mat to get to the floor.
  4. Removed the four philips screws that go to the square pannel in the middle and remove the plate. 
  5. You will see a plug with three wires going to the tank, remove the plug. (If you like you can remove this unit and pump your fuel out at this point)
  6. Also remove the breather hose that goes to the top of the tank.
  7. My truck features the extra two tanks in the side pillars so I jacked up the car, removed the clamps from the large hose that goes to the lower tank and disconnected the hoses. You will need to squeeze them to get them off. Then lower the car back down. 
  8. Then I removed the lower hose that feeds the fuel system and drained the tank into a diesel container. (Note this will not remove all the fuel)
  9. I then removed the return fuel line at the top of the tank.
  10. I then placed a hydrolic jack under the skid pan and jacked it up just enough to hold the tank in place. 
  11. Two metal straps are all that holds the tank, so simply remove the 13mm nuts and remove the straps. 
  12. Now slowly lower your jack and the tank will start coming out back first. Watch out not to spill the remaining gallon of fuel.


Rust on Bottom of Old Tank
With the tank out, I noticed the skid plate for the fuel tank was rusted BAD and had started to cause pitting on the bottom of the tank. I did not see any leaks on the tank, but did notice a previous patch on the left side. I also noticed where the tank had been dented in on each side probably from some serious off road use!

The skid plate was going to need to be replaced, the tank replaced or at least reconditioned and I would upgrade all the small rubber fuel hoses. Now the fun.

If you have an early model G-Wagon you probably know about the plastic tank conversion. Quick summary: for about $1200 you can purchase a new plastic tank and for $1800 more the kit to install it. The upgrade is a good idea because plastic is better than metal for a BUNCH of reasons. Before we talk about what I decided to do, let me give you some important HARD TO FIND info that will save you money and time.
G-Wagon Fuel Tank
Original Tank From top back
  • The Mercedes part number for the new Plastic Tank for the W460 and W463 is A4604701201.
  • The Mercedes part number for the installation kit is A4614700004.
  • You can get these parts for a LOT LESS from a German parts supplier at: https://en.partacus.de. € 584.25 for the tank and  € 674.12 for the kit. Even with freight that is half of what they are selling for in the states!
New Plastic Tank A4614700004
I'm keeping my car so I considered ordering the kit and the tank. Delivered it would still be $1500, but that would mean I could only use one of the extra tanks fitted on my car. The one on the driver side would not be able to be used. I would have a nice new tank, new fuel sensor, new tubes, new, skid plate and new straps. Pretty much guarantee no more fuel problems for me and my G-Wagon. But I decided to keep looking.

I've got a couple of classic cars and decided to look at fixing the tank and maybe getting a new plate made. I know fellow car enthusiasts that have had major tank work and they look great and work for years.

The folks I found locally (State Automotive) use a process called RenuThe tank is cut open, sandblasted inside and out, holes repaired and sealed with special Renu coatings. They look great and are sealed in a way where they will virtually never rust. The entire process cost just over $500 and in two weeks I had a virtually new tank.


G-Wagon Fuel Tank
Reconditioned Fuel Tank
They pulled out all the dents and with the new finish the tank was tough and solid. Actually, I think it is now better than new and should resist all corrosion. They even said there was a lifetime warranty for as long as I own the car. The best part, it was an exact fit.

I purchased all new hoses, new clamps and sanded down the straps and applied primer and three coats of paint so the straps would look as good as the tank. I installed the tank without the old rusted skid plate for now and it looks and works great. 

If you are doing this yourself, make sure you keep the inside of the tank clean, don't get the supply and return on your diesel lines reversed and make sure all hoses are well clamped to eliminate the risk of any air getting into the fuel lines. Once installed you may need to use your diesel primer pump to prime the fuel system. 

One more thing to check: After the install of the new tank, my return lines were seeping at the joints and I was getting a lot of black smoke. I pulled off the return line from the engine and applied some pressure and found the fuel was not going anywhere. The return line was clogged and since the seeping was all the way at the tank, it had to be in the tank. I ran the tank to almost empty, removed the line going to the tank and used a thin flexible wire brush to clear the line. When I first inserted the brush, there was a lot of blockage, but with a little pressure I was able to clear the line. The car instantly ran better and all of the seeping stopped. 

With the tank reconditioned and installed, it was time to start thinking about the skid plate that covers the bottom of the fuel tank. The skid plate for the metal fuel tank and the plastic tank are different and don't look to be interchangeable. Four by Four Club is the only place I found the old style plate and it is expensive, like $550. CLICK HERE for the plate for the gas version and I believe it will work for the diesel as well, but a quick call to Vlad will verify if it works for the diesel tank. ORC also makes aluminum front and back skid plates for the W460 and W463 G-Wagons but they are designed to work for the new plastic tanks as well. 

I decided to visit a local sheet metal shop, Sheet Metal Fabricators, and see what they could do. Showing them the rusted rear skid plate they said they could fabricate one for less than $400. He could not reproduce the grooves but otherwise it would work perfectly. I asked if they could make it from aluminum and they said it would not cost much more. Lead time: two months. When complete, I'll have it powder coated red just for fun and it will be as nice as the ORC versions. 

Stand by for results.