Re: Mercruiser i/o will not go into neutral


"markvictor" <coppercollar1@xxxxxxxxxx> wrote in message
news:1138084542.168089.127580@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Jeff Rigby wrote:
>
>> All correct except the shift engine kill switch SHOULD engage if there is
>> any resistance disengaging from reverse or forward into neutral.
>
> I agree, but when the control cable and lower shift cable are in good
> condition, and adjusted correctly, the only way the clutch is "loaded",
> is essentially when underway above nominal idle,or excessive rpms prior
> to shifting, thus keeping tension on the clutch dogs.
>
>
>
> if the cables are out of adjustment, When trying to engage
> from neutral, if the rpm's are too high from premature throttle
> opening,the clutch will resist and the interrupt switch is actuated.
> When in gear,if the throttle is not closed and rhe RPM's are ,once
> again, higher than nominal idle speed, the clutch dogs resist
> disengagement, again tripping the interrupt switch...

>> This resistance (if shift cable is good) comes from the dog gear not
>> disengaging
>> because the engine is running faster than the prop. The kill switch
>> engages
>> and the motor slows relative to the prop and the gear can disengage.
>
>
> If the engine is running, and the drive is engaged (in gear) It is
> absolutely impossible for the engine to EVER run slower than the
> propshaft

OK, got me on terms, I should have said that there is pressure on the dog
gear because the engine is turning the prop against the resistance of the
water. So to be VERY specific, at idle speed there is resistance from the
prop and it WANTS to turn slower but cant because it's in gear. Because of
this the dog gear can not disengage so as you shift from either reverse or
forward into neutral the kill switch momentarilly kills the ignition so that
the engine is NOT putting drive pressure thru the gears on the prop and the
drive gear disengages.

.. A momentary spark interruption does not
> stop the engine. If you try to do full throttle direction changes, the
> interrupter should move to prevent damage, but in normal operation, the
> throttle hits the stop before the shift action proceeds, and the
> decelleration of the motor unloads the clutch dogs, and if the boat is
> moving, the flow of water over the prop actually aids in unloading
> it....

Correct;
This kill switch is not necessarry if you are throttleing back from a plane
and shift into neutral. The prop is trying to turn faster than the engine
because the boat is coming down from speed and the water is turning the prop
faster than the engine. It's also not necessary if your prop is out of the
water because there is no load on the prop/dog gear

Bottom line, the two causes of interrupter activation is
> attempting high load shifts, either from too rapid shifting at high rpm
> or misadjusted cables, or a simulated shift load caused by resistance
> from a damaged cable or possibly a heavily worn selector shaft bushing
> and seal.

Correct
>
> scottfyi@xxxxxxxxx wrote:
> When the boat is in the water and I
>> switch the gear shift to neutral, it will NOT go into neutral most of
>> the time...it just stays at the "no wake" speed but the shifter is in
>> neutral. I have to shift it back and forth to get it to finally go to
>> neutral. Any help would be greatly appreciated.
>
> The fact that the control handle is in the neutral position but the
> clutch is still engaged, is a pretty clear indication that there is not
> enough throw on the lower cable. This is often caused by the cable end
> on the interrupter bracket being positioned incorrectly in the slot on
> the cantilever.. On the v8's and v6's it should be at the bottom of the
> slot, but if memory serves me correctly, the 4 cyl. plate is inverted
> and the cable should be at the top of the slot. That will increase
> throw on the lower cable, and minimize or eliminate any unnecessary
> movement of the switch.

If it was a bad cable, or high rpms, it would stall the motor while hunting
back and forth to find neutral.

I did have a bad shift cable that didn't cause symptoms like you'd expect,
I had a shift cable problem where the kill switch was not being engaged and
the outdrive would have problems going into and out of gear. This happened
only in the morning and by warming up the engine (shift cable) the problem
went away. Replacing the shift cable fixed this problem

I also had a bad cable that manifested symptoms that were slightly unusual,
the engine would stall when docking, upon further testing it was extreme
outdrive angles while shifting that caused the stalling (the only time I
used extreme angles (steering) while shifting was when I was docking the
boat). Bending the shift cables by having the outdrive at extreme angles
caused them to bind internally and hang causing the kill switch to stall the
engine. Replacing the shift cable fixed this problem.


> trainfan1 wrote:
>
>> Yes, it should... not entirely, just enough to shake the clutch dog off
>> the gear
>
> No, it shouldn't, unless something is wrong...or you're shifting
> improperly, such as lock to lock..
>
>> Different adjustment.
>
> Of course it is, it's the throttle cable, but that can cause premature
> opening of the throttle plate, which in turn causes rpms to increase
> prior to gear engagement,which causes increased effort tho engage the
> clutch dogs,which should cause the interrupter. to actuate, which
> causes the boat to stall, etc etc,...But that's what's supposed to
> happen if the throttle opens too soon....
>
> Jeff Rigby wrote:
>> Probably the shifter cable is bad, your shifter kill switch is not
>> engaging.
>
> That is when it would engage, if the cable was bad
>
>
> JIMinFL wrote:
>> The shift bellow doesn't seal water out of the cable. If the bellow leaks
>> the boat will take on water. A defective shift shaft bushing is the main
>> cause for water intrusion into the shift cable
>
> You're absolutely right,,,
>


.

Relevant Pages

  • Re: Mercruiser i/o will not go into neutral
    ... > All correct except the shift engine kill switch SHOULD engage if there is ... but when the control cable and lower shift cable are in good ... > because the engine is running faster than the prop. ... or misadjusted cables, or a simulated shift load caused by resistance ...
    (rec.boats)
  • Re: Mercruiser i/o will not go into neutral
    ... >>> All correct except the shift engine kill switch SHOULD engage if there is ... >>> because the engine is running faster than the prop. ... Bending the shift cables by having the outdrive at extreme angles ...
    (rec.boats)
  • Re: Chip control of auto transmission shift points?
    ... If so, I would imagine the shift points, both down and up, can be readily ... I feel it shifts *down* too soon on hills, with gas, etc, and would like ... I highly doubt any dealer would install an engine blowing chip. ... down a gear, but the mpg's drop 30% as well. ...
    (rec.autos.tech)
  • Re: How would you do it?
    ... Old school is let the engine work for you. ... No need to shift more than you have to. ... truck would come into the power range just fine. ... Also we would laugh at a driver that had to ...
    (misc.transport.trucking)
  • Re: shift interrupt switch
    ... box attaches and also the cable to the lower unit attaches as well as the ... This is where the shift interrupter is located. ... Usually the best solution is to replace both of the cables and the shift ... special tool to install the threaded end on the lower unit end, ...
    (rec.boats)