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  • Shift interrupter problem

    Hello, so my head gasket repair on my 85 merc 3.0 was successful, no more water in the engine, good compression etc. now I’m battling this shift interrupter problem. At first the engine would die going into gear if the cable adjustment wasn’t right and die every time shifting into neutral so I replaced my lower shift cable. Only replaced the inner core due to not having the special tool. Now the unit shifts into gear without dying ever but will still die going back to neutral when in the water under load. I think that the problem is related to either A - excessive play in my upper shift/control cable, or B- wear in my HI-LEX POS control. I think that because the interrupter will not kill the engine when I shift real quickly back into neutral and give the throttle a jiggle once in neutral. There has always been some play in neutral where I frequently have to move the control a little I think usually coward sighing leaving neutral just on the front end of the play it has to start the boat because otherwise the neutral saftey switch won’t allow the ignition to work. So back to the interrupter when I shift quickly back to neutral after being in gear if I don’t find that same area within the play quickly the engine will die...could the interrupter interact with the neutral saftey switch? Controls are expensive so I have begin putting that off. Do you think a worn control cable could be causing this? I don’t think it is an issue related to keeping the lower shift cable jacket in place since the issue with dying going into gear has been resolved. I think it has to do with this play in neutral? Any suggestions or tips?

  • #2
    A couple questions:
    Did you have a shifting problem before your engine repair?
    Did you verify the length of the replacement lower shift cable core is EXACTLY the same length of the original? (Merc advises against a core replacement)
    '96 Larson 174 SEI BR. 4.3LX 4 bbl Weber s/n 0F786604. Alpha One Gen II s/n 0F709315

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    • #3
      Before I repaired the engine and replaced the lower cable the boat would shift fine on the trailer but in water it would die going out of gear every time and also sometimes going into gear. Since the repair and the cable switch I haven’t had an issue dying going into gear and instead of dying every time going back to neutral it just happens once out of maybe 5 or less it really seems to depend on how quickly I can return it to neutral and jiggle the play in the control in neutral.. I think my upper cable is worn and has excessive play because the procedural shift adjustment does not work. 6 inches on the lower cable and 4 turns away from the cable with the upper. Seems that if I follow that procedure I can find forward gear but not reverse or vice verse. To get both to engage I have to mess with the upper cable a little more and do it more by feel. I got a new upper cable to install but am doubting it will fix my interrupter issue. Right now I have it adjusted where I can go back and forth in and out of gear but like I said there is play in the neutral and if I don’t shift quickly into neural and jiggle the control a little the engine dies... and yes I do think the inner cable was the exact same as the one that was replaced I put them side by side and ordered the kit from iboats just didn’t replace the outer due to not having the tool.

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      • #4
        Regardless of how bad the remote control or remote control cable is, it CAN NOT cause the switch to activate. If the switch is activating when it shouldn't, it's a problem from the shift plate, down....

        Have you look at the video I did? If not, I suggest you do so. Plenty of info in there that should lead you to finding the problem.

        Something that just jumped into my mind is the vee-spring on the back of the lever. If that's weak, or broken, you'd get the problem you're describing... Just a long-shot W.A.G.....

        Chris......

        (#5 in this drawing)

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        xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
        The world takes on a whole new perspective when viewed from 100’ below.
        1972 Bertram ‘Bahia Mar’ 20
        2006 Mercruiser 4.3MPI (0W617679) w/Alpha One Gen II (0W829301)
        (Original - 1972 '165' In-line 6. Previous - 1994 4.3LX)


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        • #5
          Hi Chris thank you for the reply. Yes I follow the instructions in the video and that is why I replaced the lower cable the play was out of spec. It’s weird that it could be a mechanism in the shift plate because it was doing this last week so I ordered a replacement shift plate with the switch and everything and it is still having this problem with the new plate. It was a used part they said freshwater and it really seems like it when I operate the switch my hand it springs right back and I am guessing since it has happened on 2 plates that the problem may be in the drive itself?

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          • #6
            I’m not sure if the switch is activating when it isn’t supposed to since I changed the lower shift cable. It only dies coming out of gear not going into gear like it used to. If I shift out of gear slowly it will die or if i shift and do not find the sweet spot in the control. It’s like the switch is being activated for too long for some reason... or my engine is still low on power to not recover. Do you think this could have to do with running without a thermostat? I haven’t put a new one in yet because when I replaced the head gasket my neighbor who helped convinced me not to put it in...after reading and advice to the contrary I realize I should be running with one...and I know we talked about how I shouldn’t listen to my neighbor because he’s a car mechanic but I did this before those words of wisdom, and he does work on boats too but he doesn’t know stearndrives it doesn’t seem.

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            • #7
              What brand of lower shift cable did you use, aftermarket or OEM Quicksilver? Reusing the old outer cable case could be causing your problem as the case can get worn from the old inner cable.

              I installed an aftermarket cable and it worked OK, but then quickly developed engine dying problems, cable dragging. Replaced that POS aftermarket cable with an OEM Quicksilver lower shift cable and it's been shifting perfect for 6-7 years..... Quicksilver shift cables are built different (at least different than aftermarket 7 years ago) as they have 1 wire wrapped over the main cable and a teflon(?) coating, so the inner/outer cable contact is less and more slippery.

              I use a lot of aftermarket parts, but would never use an aftermarket lower shift cable again.

              You may want to check the shift shaft in the bell housing, to make sure it's turning freely, if it's binding it can cause shifting problems, bushings could be bad. I had to put the "foot" end of the shaft into a vice and bend it closed a bit, since it had spread out over years, there was a lot of slop between it and the drive's intermediate shift shaft. Bent it back to where there was just a tiny bit of clearance, so it didn't bind.
              2001 Crestliner SuperHawk 1800, Mercruiser 140HP
              2007 Tracker 1436 jon boat, 7.5HP Force

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              • #8
                Recently we had a shift problem thread, and the problem turned out to be the rubber washer on the top of the lower shift shaft in the lower housing.

                Thermostat... Yeah, car engines can 'get away with it' to a degree because the water is a closed system and it will be circulating warmer water anyway. A boat on the other hand will be pulling COLD water in all the time, so running with a thermostat is a very bad idea.

                If I was doing the repairs here, I would pull the drive and verify the shift plate to upper shift shaft was all good, including that the slide on the end of the cable is able to rotate freely (this is one a lot of people mess up, tightening that grubscrew and jamming the slide)... Check the upper shift shaft bushings and seal are in good condition and not binding the shift shaft...

                If that all checks out, turn the intermediate shift shaft and make sure it's free. If it's not 100%, split the drive and check the intermediate shaft isn't bent, check the 'shoe' is not slayed (close it up with vice grips if it is)...

                Next check the washers on the top of the lower shift shaft, make sure they aren't damaged. The only thing left after that is the lower shift shaft bushing and seal.

                Good luck

                Chris.........
                xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
                The world takes on a whole new perspective when viewed from 100’ below.
                1972 Bertram ‘Bahia Mar’ 20
                2006 Mercruiser 4.3MPI (0W617679) w/Alpha One Gen II (0W829301)
                (Original - 1972 '165' In-line 6. Previous - 1994 4.3LX)


                Comment


                • #9
                  Regarding "A boat on the other hand will be pulling COLD water in all the time, so running with a thermostat is a very bad idea."

                  I think you meant "withOUT a thermostat". or do I owe an apology and need to take Internet Boat Mechanic-ing 101 over again...
                  2002 Bryant 188 4.3MPI

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                  • #10
                    Only replaced the inner core due to not having the special tool. Now the unit shifts into gear without dying ever but will still die going back to neutral

                    You dont just replace a core because the core never wears, the inner plastic core the shift cable core goes in wears a groove and creates the excess play.
                    NO PERSONAL QUESTIONS, THIS IS WHAT THE FORUM IS FOR.

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                    • #11
                      The part that Chris wrote about the thermostat is the part I really understood. He meant I need one. The rest I only partially understand. One thing I do know is that I am happy that it could be something else besides just the cable adjustment because I have adjusted the thing to death. I’m going to pull the drive and replace the outer lower cable and hope that is the problem. I think the slide did turn freely but I am pretty sure I tightened that skrew pretty good though.. the wire that goes on the end I lacked the twisting skills to make it look anything like how it is supposed to. I’m going to inspect and split the drive as recommended I will have to do some research to identify all these parts I don’t know them really by name I’ve been calling the shift slide “that **** thing due to the fact that when you put the drive back on its one of many****ing things you have to make sure line up. Thanks again Chris for the help. I’ll be sure to post a thank you the day I have a safe shifting running boat floating around.

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                      • #12
                        Originally posted by Maclin View Post
                        Regarding "A boat on the other hand will be pulling COLD water in all the time, so running with a thermostat is a very bad idea."

                        I think you meant "withOUT a thermostat". or do I owe an apology and need to take Internet Boat Mechanic-ing 101 over again...


                        Yes, thank you. "without"...

                        Chris....
                        xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
                        The world takes on a whole new perspective when viewed from 100’ below.
                        1972 Bertram ‘Bahia Mar’ 20
                        2006 Mercruiser 4.3MPI (0W617679) w/Alpha One Gen II (0W829301)
                        (Original - 1972 '165' In-line 6. Previous - 1994 4.3LX)


                        Comment


                        • #13
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                          The screw in the end of the slide should be snugged up and then backed off 1/4 turn before installing the lock wire.
                          "Growing old is mandatory. Growing up is optional."

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