Volvo penta 120s saildrive problem

[Pelican Dave]

Hey guys, I have a 120s saildrive on a Volvo penta md7b engine that will not go into neutral when the engine is running. It will shift into forward and reverse just fine, but if I want to go into neutral I have to first shut off the engine, shift into neutral and then turn the engine back on.
Anybody got any ideas?
Pelican Dave

[Pelican Dave]

Anybody?

[DougR]

This happens when there is wear in the internal shift mechanism. It might be able to be adjusted with shim removal from the outside, or it might require replacement of some worn shifter parts.

Unfortunately a full description of the cause and remedy takes more time than the forum allows to answer, so I suggest an experienced technician have a look at it.

[Pelican Dave]

Thank you.
Any shot fairly handy guy on a budget, but certainly a non-mechanic has chance tackling this on his while in the water?

[DougR]

It’s possible that you can try to do some adjustments from the outside, and it’s possible to check to see if there is lots of wear on the shifter parts.....

The photos are from a new MS2 inboard transmission, but basically the same as your saildrive.
Photo #1- from the outside...you see the adjusting bolt with its shims, which is mounted in the threaded hole on the outside of the shifter mechanism, also see the shift shoe & spring which is mounted in the shifter on the inside. The spring end of the shift shoe pushes against the end of the adjusting bolt.
Photo#2- The shift shoe located in the shifter
Photo #3- looking in the gear you see the groove in the shift cone where the shift shoe rides, and allows the shoe to move the cone up or down to engage the cone clutch.

The pressure of the shift shoe against the cone allows the shoe to break the “suction” of the cone and the gear and pop the cone out of engagement when the engine is running. When the engine is not running there is no “suction” so it shifts easily. ( It’s not really suction, but it’s the force generated by the cone being mounted on helical splines on its shaft.)

As wear occurs on the cone and shift shoe the pressure between the shift shoe and the cone lessens and shifting becomes harder. What you can do is remove one shim at a time from under the bolt head and test the shifting. Hopefully you will regain shifting before running out of shims. If wear is too great you may have to replace the shift shoe or the shift cone.
If you decide to remove the shift mechanism to have a look for wear, be sure to reinstall the shift shoe the same way it came out. It isn’t semetrical, one end of the shoe protrudes further than the other and that end wraps around the shift cone.

[JustinG NZ]

Hi DougR.
Hope you are still here and well.
I found this very informative post, and thought it might apply to my 1987 Volvo 120SB sail drive.
It has done 4,200 hours, and is starting to occasionally jam when shifting. It has happened 3 times now (with a number of successful trips between those times). In my case, it will not shift from forward into neutral or reverse. The first 2 times it happened, I worked the gear control back and forth a couple of times. It then shifted. The last time it happened, it would not get out of forward gear. The engineer came to the boat, disconnected the shift cable, and we got the engine started (still in forward). He was then able to force the gearshift (manually at the gearbox) to move to neutral and reverse. After that, he re-attached the cable ensuring it was exactly correct as per the controls, and we tested it in forward, neutral, reverse etc. This all worked fine. He suggested to use the boat and see how it goes.
I feel that if the shim adjustment is designed to adjust for wear as per your post here, maybe we should try that? What would you advise.
Cheers, Justin.