Re: Mercruiser i/o will not go into neutral

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...Alpha ratios (1.50 1.62, 1.81, 2.00, etc..) are all greater
than 1. This means that with a 1.50 to 1 gear ratio, the engine is
turning one and a half turns for every one turn of the propshaft...so
at 1500 tach rpm, the shaft is turning 1000rpm...at 3000 tach rpm, the
propshaft turns at 2000 rpm...at 600 tach rpm the shaft turns at 400
rpm,...at 150 tach rpm, the shaft would turn at 100 rpm aand so on,till
the engine is at a dead stop. 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....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.

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

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

The engine has to be moving slower than
> the prop for the gear to go into neutral thus the kill switch. (In the water
> because of the inertia of the water the prop is always going to be running
> slower than the engine unless the kill switch is working.)

I repeat, as long as the drive gear is engaged the engine will turn
faster than the propshaft,
it's a positive engagement clutch, ans a fixed ratio...there can be no
change of one without the same proportional change of the other until
AFTER disengagement occurs, not before...

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,,,

.

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