Went out to our 1993 33.5 last Friday only to be greeted with an intense diesel odor. Tracked it down to the fuel tank having a puddle underneath it with some collecting in the sump aft under the quarter berth. This tank was changed 9 years ago with a new aluminum one from Ezell Industries who, I'm guessing, was the OEM supplier to Hunter. Traced the leaks down to two pinholes almost in the center of the tank. It looks to me like the holes are a result of internal corrosion. I was able to easily poke a small screwdriver though them and the metal looked really thin at the edges of the holes. I have a local welder who can weld these up but am I wasting my time and money by not knowing how bad the rest of the tank bottom is?
33.5 fuel tank leak
- Thread starter Sutric
- Start date
Sorry to say it's a waste of time. Whatever corrosion process caused the pinholes in that location is also at work causing porosity on the rest of the tank bottom. From what we're able to see of the two pinholes, your welder may not be able to find enough aluminum thickness to weld a patch over the pinholes. That also applies to any other proposed welding on that bottom.
It was sitting on plywood but it wasn't rotted. I couldn't tell you if it was damp because of all the diesel that leaked out.
Best to take the tank out and either replace with poly or another aluminum, or if the sides are OK, cut out the old bottom and weld in a new bottom plate. A doubler plate is not a good idea because water will get in the pinholes and get between the bottom and doubler and quickly corrode the doubler plate bottom.
How much trouble is it to remove the fuel tank? I've seen a few posts about tank leaks and wondering if this is in my future.
It is a large PITA. Luckily for me the previous owner cut a large hole in the aft bulkhead that we could use to get the tank out. We also had to take out the batteries above the tank and remove the floorboards below them. As the tank was pretty full, we had to siphon out 16 gallons of diesel. Then, when all that was done someone has to lay on their side in the quarter berth and try to wiggle that thing through the opening. All in all, it took 3 of us about 4 hours to get the dang thing out and in the back of my truck.
Attachments
IMHO the correct way to support a new aluminum fuel tank is to bond plastic isolating strips to the bottom of the tank and to place the tank on a sealed plywood surface that has drain holes throughout. This is not my idea but one I found researching on line and applied to my own tank replacement. See photos below.
Here is a picture of the new tank installed. I bought an off the shelf 15 gallon plastic tank from Moeller. Since it was smaller than the original tank the installation was much easier. It's resting on a bed of Dri-Decking. It was a bit tricky to get the vent and fuel fill hoses hooked up due to the limited space overhead but we got it done! Best part is that you can see the fuel level just by opening up the inspection port in the aft berth and shining a light on it. Feels good to have it running again.
Attachments
Would you be kind enough to send me more information on 15 gallon tank. Also how did you get old tank out?
Thanks
Question? Has anyone cut a hole in top of poly fuel tank were you could clean the bottom of tank? If so what did you use to seal hole up with?
What do you expect to find in the bottom of a fuel tank ? If the fuel is properly treated with a biocide like Biobore, it should be clean.
Every so often I'll use the Pela oil extractor to go in through here and pull a sample to check for water on the bottom of the tank.
Any hand hole large enough to enter the tank is looking for trouble in the form of a leak.
I put a similar Moeller tank in my boat, 19 gallon, it's great. One thing I would caution you about is making sure the tank is secure and will not move about when sailing. See if the straps are enough to hold it from sliding sideways. Moeller sells some mounts that will help: https://www.amazon.com/Moeller-Perm...ocphy=9001873&hvtargid=pla-493053509998&psc=1
I have straps and the Moeller mounts and it still moves a bit from side-to-side so I'm in the process of building a wood beam to capture it on the side (one side is already against fiberglass). A full tank is pretty heavy. My original tank was captured on all sides by a plywood frame.
Sure, Here is a copy of the drawing that I got from Moeller. We detailed what was involved getting the old tank out above. Suffice to say it was a PITA! I don't know what would be involved in getting out of a 31. Good luck!
