Logo
FULL SITE MENU

alpha one neutral adjustment

L

lscott

Member
Hello 2001 Maxum 2300sc 5.0 mercruiser alpha one drive.


I have a problem shifting into neutral from either forward or reverse. The drive/prop is still being driven, the handle feels like it is in neutral and I can shut off the motor and restart with no problems. it seems like if I "pop" or "smack" the handle it will actually go into neutral. This was a real problem when docking and maneuvering, actualy became a problem today combined with wind and waves while wifey was bringing the boat to the trailer.

I think the adjustment should be at the engine side not the handle side since the engine is still really powering the prop. Advice requested

Thanks Again.
Larry
 
Not sure, how does it act when it works? There is no grinding or lurching when going into or out of gear, I cant say for sure if the tach shows much drop in rpm, it when engaging the drive.
 
What the shift interuptor does is this,

When shifting OUT OF GEAR ONLY, FORWARD OR REVERSE the gears in the lower unit do not want to seperate due to cyntrifical forces. This puts a strain on the SHORT SHIFT CABLE and causes the V notched piece of plastic on the shift bracket to move. When it moves it activates the interuptor switch causing the ignition to shut of for a split second (this alows the gears to seperate in the lower unit). (if you try to shift out of gear very slowly you could stall the engine).

So to test the switch, start the engine (in the water or with water muffs on) and simply depress/activate the switch with you finger or a screwdriver.
The engine should stall. If it does not then either the switch is bad or a wiring issue has occurred.
 
Iscot, as per Bt Doctur, who happens to be in surgery at the moment, the SI is to momentarily stumble the ignition (i.e., lower rpm) as to quickly remove the load from the dog teeth.

Let's back up for a moment.
The nature of dog clutch engagement is that the actual dog teeth are cut at an incline, so that when engaged, the prop thrust tends to further hold these teeth engaged. As long as the propeller is providing thrust, these teeth will remain engaged.
We need to over-come this force when coming from gear back into neutral.
The way that this is achieved, is by reducing prop thrust to below that of the hull's fwd speed.

The disengagement requires some force against the cable, the shift rod, the shift spool, and eventually the sliding sleeve and gear dog teeth. This resistance is ultimately realized at the lower shift cable outer jacket.
The cable's outer jacket resistance applies force to the shift cam lever...... (or which ever term you want to use).
As the cam lever moves, it operates a micro switch (this is done in a fraction of a second).
This micro switch is what momentarily stumbles the ignition and engine rpm.
Once RPM is lowered, now she is free to quickly come from engagement to disengagement.

The key to this (baring that all is adjusted and working correctly), is a quick and concise shift lever movement.
If we do this too slowly, we will not get good results.

Any adjustments to the SI must be done while the boat is in the water. If not in the water, we can't create the prop thrust.
No prop thrust...... no resistance.... no resistance.... no adjustment can be made with any accuracy.
IOW, if your mechanic says that he can make an adjustment while the boat is on the hard, he's either very skilled, or is not being honest with you.



Edit:
I just now say Paul's post.
I'm not quite following his centrifugal force analogy, but I'll ditto his suggestions.

.
 
Last edited:
it doesnt seem to matter if the shift is slow or fast , it seems the drive is still in gear even thought the handle is in the neutral position and like i said lightly smacking the handle will get it out of gear.
Seems logical that the si needs to be tested because if I shut down the engine it starts back up in neutral.

ok where is this switch located on top of the engine?
 
Last edited:
lscott said:
it doesnt seem to matter if the shift is slow or fast , it seems the drive is still in gear even thought the handle is in the neutral position and like i said lightly smacking the handle will get it out of gear.
Seems logical that the si needs to be tested because if I shut down the engine it starts back up in neutral.

ok where is this switch located on top of the engine?
Click to expand...
The SI has nothing to do with starting in or out of gear. That would be your neutral safety switch.

It sounds as though your SI is either not working, or is out of adjustment.
I would correct this ASAP, or you many end up with damage.

Yes, the SI system will be engine located. Look at where both shift cables attach at the bracket affair.
This unit is your SI system.
The short lower cable is the cable that operates the cam lever via it's outer jacket.

.
 
RicardoMarine said:
Edit:
I just now say Paul's post.
I'm not quite following his centrifugal force analogy, but I'll ditto his suggestions.

.
Click to expand...

It is cintryifcal forces that keep the clutch dog teeth engaged to each other (clutch dog and either forward or reverse clutch dog engagement teeth) and make it difficult for them to seperate.

I was keeping it as simple as possible as it does not appear he is technicaly savy in marine mechanics, at least not yet. So I left out the BIG PICTURE.

And it is JACK, not Paul........


If the switch works as I described then the switch may need to be adjusted,

I am not sure what switch he has. If he has the older style with the small roller wheel then it can be adjusted, The arm of the switch can be bent SLIGHTLY to make the switch activate sooner.

If it is the newer style (just a in/out button style) I believe the switch can be loosened and moved closer to the V notch.
 
Ok not Tech savy on boats but there isnt anything I cant learn.. Ok so a SI switch is seperate from a neutral switch. I think what I meant by shutting off and restarting was 1) I really am in neutral 2) the prop is no longer being driven on restart. Makes sense to me that the Si is the problem, if i need a temporary reduction in torque to allow the outdrive to engage or disengage

It will be the weekend before I can dig into it some more. I will also research my manuals what they are to find it. Got a picture or video of what I am looking for. Thanks for you help!!!
 
You only want the shift interupter to work when coming out of gear to temporarily remove torque from drive and let the gears disengage. If the SI switch were to also

do the same when shifting into gear, chances are it might stall the motor.
 
Welcome aboard !

Before you do anything... when you get to the boat... Always have water going to the drive when starting it. Tell us when asking questions if the boat is in the water or on the hard.

Start the engine, see the shift bracket on the engine the shift cable goes to it there will be a micro switch, the shift bracket moves and engages the switch, depress the switch with your finger, does the engine stumble ? Is the switch hanging up maybe sticking ?

No then remove the shift cable coming from the throttle off the shift bracket. Now move the throttle like you were going to shift into gear, the cable sticking ?

Yes.. it could be the control or the cable. No then it could be the lower cable. Common problem. And in my own humble opinion being close to a thousand miles away and not touching your boat is the problem if all the above is followed.
 
Your shift cable is either out of adjustment or needs to be replaced.Your shift arm located at your lower unit could be worn & need replaced as well.Greese,oil things up.Inspect for metal shavings,check your gear oil for water as well.Try changing your gear oil.
 
Had a little bit of time so I checked out the SI switch
1) it does work if depressed
2) shifting does not make the switch
3) cables look good

Is there a procedure for adjusting that I can reference anywhere? maybe with pics? looks like the only adjustment is on the cable, the switch is securely mounted
 
Back
Top