'88 Mercruiser 5.7L Alpha One - Shifts into gear, but no Neutral

[gennis35]

First time posting, so I apologize if this has been covered in a previous post.

I have an 88 Mercruiser 5.7L Alpha One I/O that is not shifting correctly. It will shift into forward and reverse from the neutral position, but will not return to neutral with the engine running.

I have realigned the shift cables to ensure that they are set to factory specs and checked for excessive 'play' in both cables. Both cables appear to be well within factory specs for play/stretch.

I am wondering if my shift interrupter switch may be going bad, but I can push to button in and it does kill the engine.

NOTE: I did have the lower unit off over the winter when I replaced the bellows. I did not replace the shift cable at the time, which was a mistake in hindsight.

Any help would be greatly appreciated.

 

[thumpar]

Have someone shift it while you watch the interrupt switch action. It could be an adjustment or you could just need a new lower shift cable.

 

[gennis35]

thumpar Thanks for the reply. Yesterday, I removed the interrupter switch and bent the roller further away from the body/switch. I have reinstalled it, and now the engine is dying going into both forward and reverse. This makes me think that I over adjusted the switch, but this could still be the problem. Would that be right?

Is there a way to isolate the problem to the lower shift cable if that is the problem?

Thanks!

 

[thumpar]

thumpar Thanks for the reply. Yesterday, I removed the interrupter switch and bent the roller further away from the body/switch. I have reinstalled it, and now the engine is dying going into both forward and reverse. This makes me think that I over adjusted the switch, but this could still be the problem. Would that be right?

Is there a way to isolate the problem to the lower shift cable if that is the problem?

Thanks!

If adjusting it as per the factory manual doesn't work you most likely need a new lower shift cable.

 

[Maxum88]

Is this not shifting properly on the trailer or in the water? I had issues of very hard shifting only in the water but a breeze on the trailer. Come to find out the shift interrupt switch was actually disconnected. If it is hard to shift when on the trailer, focus on the cable.

 

[sub2010ss]

This sounds a lot like the problems I was having with my shifting. On the trailer everything was fine. Once in the water reverse to neutral was ok, but forward to neutral took forever. It always eventually shifted once the boat speed was low enough. I checked every cable adjustment and freedom of movement, cleaned all the shift mechanism components, and verified my interrupt switch actually worked. In the end I had to adjust the spring pressure on the lever that actuates the interrupt switch. I had a lot of advice about which cable was bad and out of adjustment but nothing else seemed to fix my problem. I have the new style interrupt switch. In red is the spring I adjusted. I made it slightly weaker and it works great now.

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[theorifice]

How did you make it weaker?'