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  • Fuel Tank

    Good morning

    I own a 1976 20 Mako and was looking for some advice. I purchased the boat 4 yrs ago and am only the 2nd owner.(a good find) I believe the fuel tank to be the original. The owners manual states that it is a 44 gal Stainless Steel tank. Will this tank last forever ? How long should it last ?

    I have not noticed any fuel in the bilge. How can I check to see it the tank is okay with out ripping the boat apart. I live on the north shore of MA and the boat is in salt water.

    Any advice would be much appreciated.

    Love this site
    76 mako 20 cc[br]Essex MA

  • #2
    I'm interested in this as well as it pertains to a late 80's 285.
    Dallas, TX[br](Boat at Port Aransas, TX)


    • #3

      Your nose will lead the way. I have a 1974 17CC and the tank started leaking a few years (2000) ago while on vacation in the Keys. Luckily it was not until the 2nd to last day of the trip. I started to smell gas really bad after filling the tank one afternoon. I pulled the boat out and removed the drain plug and a few gallons of nasty water followed by about 1/2 gallon of pure gas came out. I flushed the bilge and kept some water in there for the 1,300 mile ride back up 95 to New Jersey. I pulled the tank and found three different areas of corrosion and it appeared that the one that was leaking was about 1/2 way up the side of the tank in the rear. As you know, the tank was encased in foam, which traps water after time if water is allowed to enter the area and after 25 plus years. If your tank is actually stainless steel, you should be OK. But sniffing around in the bilge and unner the consol should tell you if you have a problem.

      Chris Miller

      1974 17 Classic

      1985 24 Rampage Express

      Mystic Islands, NJ
      Chris Miller[br]Mystic Islands, NJ[br]1974 17 Classic[br]1988 211 Classic (sold)[br]1990 Grady White 230 Gulfstream (sold)[br][img][br]


      • #4
        a good guide line for fuel tank life is 8 to 10 years for an aluminum tank like the one in your boat.the reolacement tank should be epoxy coated and all hosing as well as the tank bond and static bond on the fill cap be replaced at the same time.


        • #5
          I know all boats are different and this differs from the experience of a lot of guys here, but I bought a '74 Mako 20 a couple of months ago. I pulled the tank last weekend. It was aluminum and had a lot of water in the foam but the tank is in good condition. I am planning on cleaning all the foam out of the compartment, cleaning the tank, applying an epoxy coating and then putting it back like it was.

          Even though the tank was fine, I am glad I pulled it as there must have been 5-10 gallons of water in the compartment around the tank. Now I can put the hatch cover back better and try to keep the water out.

          By the way, I sure would appreciate a scanned copy of that owners manual if possible.
          Jay [br]Thomson, GA [br]1974 Mako 20


          • #6
            Make sure you check out the aluminum fill tubes and rubber hose connecters. they were what were bad in my 1980 m20. I lifted the console up about 1 foot and removed the tank cover for the work I did. Left the console hanging during the repairs. Keep us posted and you know we all love pictures of progress. dave
            [br]1994 Mako 215 Dual console Optimax 225[br]1978 Mako 19 with 90hp johnson[br]1996 Mako 22[br]1982 Mako 171 Angler 135 Black Max Mercury[br]1987 21b 225 Yamaha[br]1974 23 inboard Gusto gone.[br]1979m21 225johnson \"blue dolphin\" bought off this board and restored [br]with everyone\'s help!!Gone but not Forgotten....[br]1979 20 Mako 115 Suzuki gone[br]1977 19 Mako 115 Johnson gone[br]1976 23 Mako twin 140 Johnsons gone[br]1983 224 with closed transom and bracket[br]And 162 SOB (some other boats)[br]Venice Florida, Traverse city Mi.


            • #7
              I fully agree with michigan dave about the Al fill tube. When I developed a gas leak a few years ago on my 1973 22' CC, I found the tank to be in OK shape with only a few pits about halfway through the AL (probably would have gone another 4 to 10 years) BUT it was that aluminum fill cross over tube (from the gunnel) that had developed a leaking hole when I filled up due to corrosion from the salt in the foam that surrounded the fill tube. If you have the tank out, do not put it back without also replacing that fill tube. I used the regular 1 1/2 " USCG approved gas fill hose for the whole job, from the fill to the tank fitting. It was easy to work with and I had no problems except getting the old fill tube out. I just cut it off with a hack saw where the vertical fill tube met the horizontal fill tube and pulled the horizontal tube out. I then used a ele drill to make the hole slightly larger in the wood stringer larger and to remove the foam so I could get the new hose in place - starting from the tank side. Took some doing but I didn't need to disturb the floor or anything else like some people will tell you you need to do. Also, make sure you double hoseclamp with SS clamps and make sure you ground the fill to the tank with a seperate wire. Hope this helps -

              1973 22 CC Milford, CT USA[br]


              • #8
                100th Meridian:

                I need to correct my post from last week. I stated that my aluminum fuel tank from my '74 Mako 20 was in accepatable condition, well, I was wrong! Tonight, I started cleaning the corrosion off to prepare it for painting and wow! Deep Pitting. I am glad I took a closer look. It was in isolated areas but i actually found one place that I could stick my pocketknife through! Oh well, I guess it was just more wishfull thinking.

                Note the hole at the tip of my knife.

                This is how my boat looks right now.

                Lots of water & wet foam in the compartment.

                Sorry for the bad info.

                Still would like to see a scanned copy of that Mako 20 Owners Manual.
                Jay [br]Thomson, GA [br]1974 Mako 20


                • #9
                  Free T-shirt to anyone who can produce scans or a hard copy for me to scan for any Mako owners manual not currently listed on the main webpage. I'm not kidding about the free schwag either.[]
                  Slidell, LA 1993 Mako 261B - Temperance


                  • #10

                    I'll pay for the t-shirt if I can get a manual for my '74 Mako 20.
                    Jay [br]Thomson, GA [br]1974 Mako 20


                    • #11

                      Good thing you pulled out that tank sooner rather than later. I'm going at it this weekend on my 230, and would appreciate it if you could share any trick you used to pull that thing out. It doesn't sound like fun, and I'd like to learn from the experience of others sharing this headache. Thanks.
                      Past:[br]1988 Mako 230[br]1987 Mako 20C (best of them all)[br][br]1974 Mako 15[br]Miami, FL[br]


                      • #12

                        I had a harder time getting the hatch cover off than actually getting the tank out. Lots of thick caulking over the years. Once I got the cover off, I used Warthog5's idea of a bow saw blade with a ducttape handle and cut down beside the tank as much as possible. I then took a square end shovel and popped all of the foam off the top of the tank. I forced the shovel through the foam on the sides of the tank and then used a large scewdriver to pop that foam loose. Remember, it had been cut earlier. I have a chainfall hoist in my shop and hooked it to the tank by wrapping a nylon choker around the tall fuel gauge pipe. Because this was on the end, the tank just seemed to slowly peel away from the foam on the bottom.

                        This picture shows how I lifted it.

                        If you look closely at the picture of the inside of my boat above, you can see the saw just above all the electrical wires laying against the port side. It is wrapped with a white towel and then ducttape to make a handle.

                        Good Luck!
                        Jay [br]Thomson, GA [br]1974 Mako 20


                        • #13

                          I'll do it Saturday. I'll take pics in case something worth posting comes up.
                          Past:[br]1988 Mako 230[br]1987 Mako 20C (best of them all)[br][br]1974 Mako 15[br]Miami, FL[br]