Mercruiser gearshift problem

[ExcaliburII]

Hi, everyone. I've been hovering on the sidelines for a little while now, marvelling at the breadth of wisdom on the forum and the time has come to take the plunge, so here goes.

My Mercruiser (5.0LX, Alpha 1) has never been very good at disengaging the drive when the control is moved to neutral. I have to move the lever beyond neutral to make it drop out of gear and then bring it back again. I've had several goes at adjusting the cables, without much success to date. When I first bought the boat I had to completely dismantle the drive to fit a new steering arm, pivot shaft and bellows etc. The drive unit shift cable seemed OK when I reassembled it all as per the book - quite smooth and it didn't seem unduly stiff.

After following a link from the forum recently (thanks, guys), I found an explanation of how the shift interrupter switch is supposed to work - ie it cuts the ignition when the control is moved to neutral if the drive stays in gear. This shakes the drivetrain and allows the drive to drop out of gear easily. The switch then resets so the engine keeps running with everything in neutral. This was a bit of a revelation to me as my service manual doesn't describe all this. So I tested my switch and found it wasn't killing the engine at all. Someone before me had bent the operating arm of the switch to stop it working. I straightened the arm and promptly found why it had been bodged. Now the unit goes from astern to neutral perfectly, with just a stutter from the engine as intended. However, my problem now is that the engine stalls when going from ahead to neutral. It seems to take the drive at least a second to come out of gear and this is long enough to let the engine die before the interrupter switch resets. The drive unit shift cable doesn't seem too stiff to me - with it disconnected, I can fairly easily move it over its full range by hand with the engine stopped, but I don't really know how much force it should take. The cam that operates the shift interrupter switch also works freely. Does anyone know what might be making the drive so sluggish to come out of gear? Incidentally, I've watched the cable and it moves smoothly but slowly; it's not sticking and then letting go with a bang or anything like that.

Any advice would be gratefully received as berthing and close quarters manoeuvering is much more exciting than it should be at the moment. /forums/images/graemlins/blush.gif

 

[spannerman]

What idle speed do you have, it should be 650- 700 rpm IN GEAR.
Do you have some clearance between the roller on the micro switch and the cam, there should be about 3mm if I remember, if its less it makes the switch too sensitive and so it cuts out when going into gear. As you have figured out the switch reacts to the load on the cable when shifting, if you can't cure it by adjustment you usually end up changing the shift cable.

 

[ExcaliburII]

Thanks, spannerman. From memory my in-gear idle speed is a bit below 600 so I will try picking it up a bit when next at the boat. No problems with stalling going into gear at all - the switch cam barely moves then, hence my initial assumption that the cable drag is not excessive.