Gas Tank Question

pdm2q · Post by **pdm2q** » Thu Jun 07, 2007 10:02 am

1968 28' express - my question is ... are the gas tanks aluminum? if they are what are they made out of because i think we may have a rust problem. the fuel filter clogs within ten minutes of running it and it has to be replaced. it has to be the gas tank i would think, but if the tanks are aluminum then there cant be rust right?

randyp · Post by **randyp** » Thu Jun 07, 2007 1:26 pm

Been there, done that, with our '77 F-26. Original tank was GALVANIZED steel, and rust formed on the inside (condensation from winter storage, etc). Rust particles got sucked into the fuel line/carb and kept clogging the system, resulting in power loss, etc. Finally had to have the tank replaced and went with a poly tank. Based on some of the ethanol issues these days that result in fiberglass tanks dissolving, I'd stick with poly tanks as they are readily available.

Good luck

Randy

obeejr · Post by **obeejr** » Thu Jun 07, 2007 1:28 pm

Have you tested them with a magnet?

My 1990 tanks, which I know are aluminum, spewed a lot of brown gunk last year when I started putting in gas which had ethanol added. I thought at first it was rust, but then realized it was brown "varnish" on the sides of the tanks that was being dissolved by the ethanol. After changing filters many times, I ended up pumping out the bottoms of the tanks with an electric fuel pump, which solved the problem.

Danny Bailey · Post by **Danny Bailey** » Thu Jun 07, 2007 5:07 pm

The tanks in my 1980 F-36 are galvanized steel and something that looked like flaked off zinc was filling the check valves on top of the tanks. These valves are siphon breaks, a safety gadget. Took me a while to figure it out....I was changing filters like crazy and finally cut one open to see what was in it....Nothing!!! That's when I started searching back upstream and found the poppets in the check valves plugged tight with the 'gray dirt'. I took the spring and poppet out of all three check valves (#3 = generator) and haven't had an engine quit due to gas starvation since then. The 'gray dirt' makes it to the filter, but there is not enough of it to stop the filter up between yearly changes. If I have a hose fail around the fuel pump I guess all the gas in one tank will siphon into the bilge but what the heck....my engines run.

prowlersfish · Post by **prowlersfish** » Thu Jun 07, 2007 7:40 pm

sounds like time to get new tanks .

Danny you need to get rid of those galvanized steel tank befor you put the diesels in . Galvanized steel and diesel don't mix

Paul

pdm2q · Post by **pdm2q** » Fri Jun 08, 2007 2:08 am

galvanized steel will rust will it not???? this old engine and fuel system is about as simple as it gets so really beyond the fuel filter on the way back is essentially just the tank itself so maybe it too is galvanized steel, i was just under the impression that the stock tanks were all aluminum, i just didnt think that they would put a potentially rust able tank in the boat. so i assume that if the fuel filter is changed and it still clogs then it has to be something in the tank? anybody know how big of a tank that probably is and if the engine would have to be pulled to get to the tank. keep in mind it is a 1968 wooden TB

Danny Bailey · Post by **Danny Bailey** » Fri Jun 08, 2007 5:02 am

Any tank over long enough time will accumulate rust / sediment / who knows what inside. My problem was that the accumulated 'stuff' could not make it to the filter to be removed and discarded. Are you sure it is your filter clogging? Do you have the check valve on top of your tank? I don't get a lot of rust in the filter...it looks like zinc so I am assuming the tanks are galvanized inside also. Since I took the guts out of those check valves, I don't have a problem and would continue to use these tanks indefinately if I were not repowering to diesel this fall. I'll be pulling them out and replacing with aluminum or stainless...haven't quite decided which yet. I'm leaning toward stainless. Any recommendations?

Paul · Post by **Paul** » Fri Jun 08, 2007 8:33 am

Hi Danny,

I would choose the aluminum over stainless for two reasons. First is the weight of the stainless is 3 times the weight of aluminum. Second is that regulations for new boat builders do not allow them to use stainless for fuel (gasoline) tanks over 20 gallons. I'm not sure how this affects you with diesel but the potential for a leak is there no matter what liquid you have in the tank.

I had a 75 gal 316 Stainless Steel tank in my boat that I had to remove to make room for a generator. I needed to have it reconfigured to go around the generator location or make a new custom tank for this application. Before doing this, I looked around on the net and found the regulations on marine fuel tanks. The regulations also cover how aluminum tanks should be mounted to keep moisture from getting trapped between the mount and the tank. Water traped against aluminum will cause it to corrode quickly. I coated the outside of my new aluminum tank with "Interprotect" epoxy to prevent external corrosion.

Danny Bailey · Post by **Danny Bailey** » Fri Jun 08, 2007 7:53 pm

Thanks for the tank info, Paul. I guess the stainless tanks are prone to work hardening and cracking. It would have been nice not to have to worry about corrosion though.