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Trim Tab pump ATF fluid capacity?-gctid341622

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    Trim Tab pump ATF fluid capacity?-gctid341622

    Hi, all.

    I've been away form the forum for a while, but hope to ba back regularly. We just celebrated the 10th anniversary of 3270 ownership (!) Time flies!

    Today I had the bottom cleaned, and ahd the diver pay special attention to the trim tabs. They hadn't been operating well enough to get on plane for some time.

    I downloaded the system and pump diagrams from Bennett, and added about 200ml (7oz) of ATF fluid. Couldn't see the level in the tank. Diver said all the tabs move, but only the far starboard one has full travel.

    Two questions (Tabman?)

    1) What are the fluid capacities of the tank and each piston? ('86 3270 has 4 sets / cylinders)

    2) Is there any danger in overfilling the tank? (I assume it should top off with tabs fully up.)

    It was a bright & sunny day (yeah!) but not ideal for looking at the tank, which has yellowed over the years. Next time I'll take a flashlight to illuminate from the side.

    Charles

    #2
    there is a fluid level check on top of the tank or res you check the fluid level when they are fully out extened .....if you over fill with fluid on the retrack function the holding tank will blow off the rubber fluid stick and make a mess (don't ask me how i know this ).....as far as one of your tabs not extending it could be low on fluid and air in the system or the piston actuator is failed for the price of them 80 bucks roughly replace them all and the fitings that go thur the transom as well its a two man job to do this ......also did u know bennett sells a gismoe to retract your tabs to 0 its about 75.00 bucks 20 minutes to install , hooks to you tab switches at you most used helm station as soon as your shut you key swich off they return to the up position each time .
    NEIL S

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      #3
      Are you sure it requires ATF fluid? Use 10W30 in mine and works fine.

      Comment


        #4
        Bennett's site specifies ATF, but says you can mix any type.

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          #5
          If tank was too low, you will have to cycle tabs full down to full up several times then top off.
          Started boating 1965
          Bayliners owned: 26 Victoria, 28 Bounty, 32, 38, and 47 since 1996

          Comment


            #6
            So, the "Full" mark is with tabs fully down? And the tank would be totally full with tabs fully up? (Just want to make sure I get this right!)

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              #7
              csea wrote:
              So, the "Full" mark is with tabs fully down? And the tank would be totally full with tabs fully up? (Just want to make sure I get this right!)
              From the Bennett troubleshooting PDF available online- Dean

              Periodically, check fluid level in HPU. With trim tabs completely retracted, fluid

              level should be about 2" from bottom of reservoir (approximately 22 ounces). To

              refill, remove lexan cover and filler plug located at the front left hand corner of the

              reservoir. FILL WITH ANY TYPE AUTOMATIC TRANSMISSION FLUID (ATF) ONLY. Brands

              or types of ATF can be mixed. Running HPU with an excess or lack of fluid will not

              cause damage to the trim tab system

              Comment


                #8
                Thanks, toucow. Not clear if the guide refers to a system with 2 or 4 pistons, but I'll assume it doesn't matter, and use the 2" mark with tabs up.

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                  #9
                  A comment on bennett trim tab cylinders, they can be serviced, the only thing that can wear out is the 2 O rings, be carefull when you replace the O rings, the assy is spring loaded, $2.00 worth of O rings is better than buying new cyl, unless you have money to waste.
                  Pat says: DO-IT-RIGHT THE FIRST TIME!

                  Bayliner 3870 "ALASKA33)
                  Twin 350 GM power
                  Located in Seward, AK
                  Retired marine surveyor

                  Comment


                    #10
                    csea wrote:
                    Thanks, toucow. Not clear if the guide refers to a system with 2 or 4 pistons, but I'll assume it doesn't matter, and use the 2" mark with tabs up.
                    You're welcome. Me neither on piston count. I do not see that specified, but may have missed it. Here's the link....

                    http://www.bennetttrimtabs.com/pdf/t...leshooting.pdf

                    Comment


                      #11
                      It really doesn't matter whether you have 2 or 4 or 6 tabs. I fill my reservoir to the "FULL" line with the tabs fully RETRACTED. Then I cycle them several times to bleed out any air in the system. Check fluid level again and top off as necessary with tabs RETRACTED. I also actuate one side at a time - starboard up/down several times, then port up/down several times. I let the pump run 2-3 seconds after full extension/retraction - you can hear the whine of the pump change when this happens. One final check of the fluid level and you are good to go.

                      As a visual check, I also place small pads of absorbent material around each hose connection and under the reservoir to watch for leaks.
                      Two C's 1990 3888 MY, 175 Hinos, Hurth 630 Trannys
                      Past Commodore Emerald Rose Yacht Club
                      Member International Order of the Blue Gavel
                      MMSI: 338030604

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