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Grinding noise in neutral

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Cfoss2010

Member
I just bought a 06 bayliner 3.0 merc alpha 1 i/o. It just got completely serviced and at the dealership seemed to be no issues. Started right up and turned it off.
brought it home put some muffs on it, started right up idled in neutral just fine, shifted into forward fine, rev’d it a little, shifted from forward back to neutral and it makes an awful grinding sound like something not catching. Reverse is fine and back into forward is fine but only when i put it into neutral.
So i shut it off, put it in neutral and starts right up with no sound, once i go to forward back to neutral it happens again. Any ideas? Am i doing something wrong, new to boats any information would be greatly appreciated.
 
Shifting to slow and without the load of water on the propeller the gears spereate by shift control without the assistance of the shift interruptor switch.

With engine OFF,
Shift into fwd,
Turn prop by hand C'Clock wise.
It should lock in gear.
Now shift into neutral,
Prop should spin free with no clicking/clacking.
If it does click/clack then it is a simple cable adjustment.
If no click/clack, go boating.
 
There’s no click/clack noise when engine is off, after doing what you said. I put it into the water and when shifting into neutral, it still makes the same grinding noise.
 
There’s no click/clack noise when engine is off, after doing what you said. I put it into the water and when shifting into neutral, it still makes the same grinding noise.

kghost said:
Shifting to slow and without the load of water on the propeller the gears spereate by shift control without the assistance of the shift interruptor switch.

With engine OFF,
Shift into fwd,
Turn prop by hand C'Clock wise.
It should lock in gear.
Now shift into neutral,
Prop should spin free with no clicking/clacking.
If it does click/clack then it is a simple cable adjustment.
If no click/clack, go boating.
Click to expand...
 
Does the engine want to stall when shifting into neutral?

Are you shifting firm and quickly?
 
kghost said:
Does the engine want to stall when shifting into neutral?

Are you shifting firm and quickly?
Click to expand...
Defiantly shifting quick and firm. No sign of the engine stalling, havent really kept it in N when making that sound for more than a second or 2.
Past weekend i took the boat out and after an hour or so of tubing it shifted into neutral fine for the rest of the day no issue. Next morning after starting it in water same issue happened again. Any ideas?
 
Cfoss2010 said:
Defiantly shifting quick and firm. No sign of the engine stalling, havent really kept it in N when making that sound for more than a second or 2.
Past weekend i took the boat out and after an hour or so of tubing it shifted into neutral fine for the rest of the day no issue. Next morning after starting it in water same issue happened again. Any ideas?
Click to expand...

Had a similar problem. Turned out that the key was stuck in the start position and wasnt returning to the run position. The grinding noise was the starter. Apparently there is an interrupter that cuts the starter out in gear, but not in neutral. Try giving the key a little nudge back to run.
 
.........
Random said:
Had a similar problem. Turned out that the key was stuck in the start position and wasnt returning to the run position. The grinding noise was the starter. Apparently there is an interrupter that cuts the starter out in gear, but not in neutral. Try giving the key a little nudge back to run.
Click to expand...

Other than the neutral safety switch, there is no interrupter that interrupts the starter motor circuit.

The A drive interrupt system (SI or SA.... shift interrupt or shift assist) momentarily interrupts the ignition system while making a shift FROM gear back INTO Neutral.



As noted, with the A drive dog clutch system, you need to make your shifts concisively, quickly and deliberately..... no slow shifts!


.
 
Last edited:
RicardoMarine said:
.........


Other than the neutral safety switch, there is no interrupter that interrupts the starter motor circuit.

The A drive interrupt system (SI or SA.... shift interrupt or shift assist) momentarily interrupts the ignition system while making a shift FROM gear back INTO Neutral.



As noted, with the A drive dog clutch system, you need to make your shifts concisively, quickly and deliberately..... no slow shifts!


.
Click to expand...

My understanding of the nuetral safety switch in mercruiser engines is that it kills the starting system when in gear. In neutral and once the engine is started, If the key remains in the start position, the starter is engaged and it will grind if the engine runs. If you move the throttle into gear, the nss cuts power to the starter and you wont get that grind noise. Move the throttle back to neutral and the nss allows power to the starter again and you get a grinding noise.

I had the same problem as OP on a 3.0l. The grinding noise in neutral went away when i tapped the key back to run. To solve it permanently I lubed the key slot with graphite. Now the key snaps back to run instead of being stuck in start and no grinding noise

Note that this is different than the typical grinding noise when changing gears in an alpha one with the clutch dog that you are referring to. As I understand OPs problem, the noise is when the boat is IN neutral, not shifting to and fron neutral.

Again, I had what sounds like the same problem, and lubing the key slot fixed it immediately.
 
..................
Random said:
My understanding of the nuetral safety switch in mercruiser engines is that it kills the starting system when in gear.
Think of the Neutral Safety switch as though it Interrupts the S (solenoid) circuit when NOT in neutral.

In neutral and once the engine is started, If the key remains in the start position, the starter is engaged and it will grind if the engine runs.
Yes, but that is not a fault of the neutral safety switch nor of the Shift Assist/Shift Interrupt system.

If you move the throttle into gear, the nss cuts power to the starter and you wont get that grind noise. Move the throttle back to neutral and the nss allows power to the starter again and you get a grinding noise.
This is a key switch problem..... it is not an issue with the neutral safety switch.

I had the same problem as OP on a 3.0l. The grinding noise in neutral went away when i tapped the key back to run. To solve it permanently I lubed the key slot with graphite. Now the key snaps back to run instead of being stuck in start and no grinding noise
Yes..... precisely!

Note that this is different than the typical grinding noise when changing gears in an alpha one with the clutch dog that you are referring to. As I understand OPs problem, the noise is when the boat is IN neutral, not shifting to and fron neutral.
Only the OP knows for certain.

Again, I had what sounds like the same problem, and lubing the key slot fixed it immediately.

Click to expand...
 
Random said:
My understanding of the nuetral safety switch in mercruiser engines is that it kills the starting system when in gear. In neutral and once the engine is started, If the key remains in the start position, the starter is engaged and it will grind if the engine runs. If you move the throttle into gear, the nss cuts power to the starter and you wont get that grind noise. Move the throttle back to neutral and the nss allows power to the starter again and you get a grinding noise.

I had the same problem as OP on a 3.0l. The grinding noise in neutral went away when i tapped the key back to run. To solve it permanently I lubed the key slot with graphite. Now the key snaps back to run instead of being stuck in start and no grinding noise

Note that this is different than the typical grinding noise when changing gears in an alpha one with the clutch dog that you are referring to. As I understand OPs problem, the noise is when the boat is IN neutral, not shifting to and fron neutral.

Again, I had what sounds like the same problem, and lubing the key slot fixed it immediately.
Click to expand...
What graphite did you use
 
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