INTERMITTANT GEAR ENGAGEMENTDISENGAGEMNENT

I have a 5.7 liter Mercruiser

I have a 5.7 liter Mercruiser 260hp with alpha I drive. Shifting into forward or reverse is smooth and positive . Once in forward at idle or low throttle on occaision it seems to jump out of forward to nuetral and back into forward in an instant. It makes a clunking noise similar to when you would manually shift from forward to nuetral. Hope you can help. Thanks Dave B

"Question for you...with engin

"Question for you...with engine off, in neutral, turn the prop by hand in both directions...if you hear/ feel a clicking noise in the prop when turning in one direction and no noise turning the other direction I would suspect you need to adjust your shifter cable as you are not fully in neutral hence if too close to reverse selection on cable, forward may jump out of gear. Also check prop hub"

"What year and how many hours

"What year and how many hours on it?
The dog clutches that engage the gears are bevelled in such a way that once they are engaged they tend to not slip out of gear easily at all. Hence the need for a shift interrupt switch to get them out of gear.

If the unit has many hours on it and if there has been any tendency to shift slowly into gear with a lot of ratchetting sounds, the corners of the dog clutch may be too rounded and worn to stay engaged.

If Ken's advice does not resolve it, you may have to have the lower gear unit serviced and the dog clutches changed. That will get pricey as you also have to change all the lower gears (the clutch faces are machined into the gear faces), re-shim the gears, etc.

You would likely be better off to buy a new lower SEI gear unit for 700 bucks and be done with it.

Rod"