tank fuel leak diesel VS gaz-gctid343811

[Guest]

I have heard about many owners off 32xx that have had diesel leak from fuel tanks, but never heard about the same problem on 32xx with gaz..

Is there somthing I have been missing, or is it realy like that ??

[iceclimber]

Yeah, I'm not sure what you are really asking. I am aware that the 32xx is "prone to corrosion" in starboard tank stern end. That's because of the boats natural list to S; and if water sits in or around around that tank corner - bingo. That's not backed by statistics or anything, just something I've read. My boat lists, and I've seen water sit in there particularly when your cockpit drain is not working correctly.

[Guest]

I am just wondring if it is like that, and if so, why ?? My boat had gaz engine when it was in USA, and I changed too diesel engine when it arrived Norway. I have had no leek from tanks. Same with another boat her. But I know about 3 other boats here, that came with diesel engine from USA, and they al have had leek from fueltanks..

Thats why I am asking seens most off this 32xx are runing in USA , if there is anyone over there have had tank leek on gaz ??

[Guest]

Yup, have replaced the stbd tank in my 3218 (1988) gas powered 12 years ago, so far port tank is O K.

[Papa_Charlie]

I believe that the reason you hear of so many 32XX's with diesels having leaking tank is that there were significantly more of them built. Thereby increasing the odds that the boat with a leaky tank would also have diesel engines on board.

It is my understanding that there is a pool of water that can form under the tank. This pool in the right conditions can cause corrosion sometimes coupled with electrolysis. That is the cause of the leaks not the fuel.

[Guest]

I don't think there is any relationship to what kind of fuel is the tank because in most, if not all cases, the leak was caused by external factors.

When we did the autopsy on ours the cause was obvious.

Bayliner chose to mount the fuel tanks on shelves with a relatively flat surface. The tanks sat on some kind of plastic strips, about 38 mm wide and 3 mm thick to space them off the shelves a bit. The strips were stapled to the shelves with mild steel staples. The tanks were secured in position by 52 x 52 mm blocks, which also had the strips stapled to them. Finally, there were two stainless steel straps, which girded the tanks and ran under the shelves to hold them down. These straps had 15 mm rubber hose over them to stand the straps off the tanks.

All of this may sound like a reasonably good installation, but there is a problem.

There is an engine room vent to discharge the bilge blowers on the Stbd side of the hull next to the aft portion of the Stbd tank. The hoses terminated in a plywood box, which was glassed into the hull at construction. The hoses were sealed to the boxes with Sikoflex, or some similar compound. Unfortunately the boxes were placed so that the hull formed a small sill, so any salt spray or rain water that entered from the outside would sit on the floor of the box rather than drain out. This rotted out the aft corner of the box, allowing this water to drip down the side of the hull onto the tank shelf. To compound the problem, the hose seal was not complete at manufacture, and provided another way for water to enter the engine room. Add to this, it seems that most of these boats tend to develop irritating little rain water leaks that allow water to enter the engine room from the strangest of places. Because most of these boats tend to have a slight Stbd. list, a lot of this water ends up in the tank shelf area.

Most of the tank leaks are caused by this water, and damage is much more common with salt water boats. The tank stand off strips are only about 3 mm thick, so it doesn't take much water on the shelf to submerge them and have a portion of the tank bottom and side wetted. The stand off strips are not glued to the tanks, so now this water will flow by capillary action between the strips and tank. When the water is eventually removed by boat action, or any other means, this area cannot dry properly and forms crevice corrosion on the tanks. Over time it will eventually hole the tank. Most common areas are the bottom aft corner and back of Stbd tank. To make matters worse, the mild steel staples used to fasten the strips will often contact the tank, which will introduce galvanic corrosion. This damage is very difficult to detect on a survey because in order to properly inspect the tank you have to remove it, which also means removal of the engine in most cases. You can remove the aft retainer block and check it. If you have signs of corrosion on the tank there, it's a pretty good bet that the tank will be compromised in other areas as well. If kept dry, it may still last for years, but on the other hand, you'll never really know for sure.

On our boat things got a bit more interesting. After pulling the Stbd tank, the offending leak was located on the lower outboard corner of the tank at the point where the hold down strap entered the tank shelf. There was a quantity of construction debris in this area between the tank and hull, which appeared to be teak and fiberglass cuttings. This was most probably caused from drilling the holes for the aft combing cap cleat mounting bolts. A combination of salt and fresh water had entered this area from the blower box and soaked this debris. This debris was in contact with the aluminum tank, the stainless steel hold down strap and the rubber hose that covered the strap. Since the rubber hose is cathodic to the aluminum tank, and the whole works was in contact with the salt water soaked cuttings, it made a perfect battery, and the electrons did their thing.

At the time, rather than take a chance on the Port tank being compromised as well, I pulled it (and the Port engine) to inspect. Very little sign of water ingress, only slight amounts of crevice corrosion on the tanks.

Needless to say I took great pains to make sure this should never happen again, but that's another long story.

[iceclimber]

Thanks, RJH for that detailed explanation. That all adds up; that water has no place to go. Obviously salt water is much more of a risk, the tanks are grounded but still. Thing to do is to get in there and inspect, and keep it dry. I wonder if some drains could be added on that shelf.

[Guest]

Well, I gues mye teori went down than, as "patti ann too" confirm that hi have had leak in his gaz.tank. Also interesting to read RJH explination about this problems. I will have too hope there want be any leak on mye st.b tank.. at least not before I am back in Norway. Have mye boat in Netherland for the moment, after trying to go on the Europian water ways down too Spain. But the boat was too high for the French bridges, so we had too stop in France, and return.... Can see the blog on http://kaj-h.blogspot.com/ at last some nice picture !! No English....