94 135 Mercury going from Neutral to Forward Gear

[Alpinegold]

The motor starts up ok. When I push the handle into Forward the motor starts to thump several times until I get the speed up. After that point the thumping noise never comes back. It only happens when I go from neutral to Forward.

I would like to get a couple opinions before I take it to a boat repair shop.

Thanks for your help

Alpinegold

 

[CharlieB]

Re: 94 135 Mercury going from Neutral to Forward Gear

Suspect the shift cable is worn and not fully pulling the linkage all the way.

With the motor OFF, have a helper shift into Forward while you turn the prop with your foot and closely watch the linkage.

See exactly how far the cable pulls the linkage, then gently give the linkage a slight nudge to see if it 'clicks' into gear moving just another 1/16 inch. If so, start planing on replacing the cable very soon as continued operation of the gears 'ratcheting' before locking into gear will round off the engagement dogs and you will then be buying a couple of much more expensive parts than a shift cable.

 

[Alpinegold]

Re: 94 135 Mercury going from Neutral to Forward Gear

Hey thank you very much. Just a couple of quick questions.

With the motor OFF, have a helper shift into Forward while you turn the prop with your foot and closely watch the linkage.

When I push the lever in forward, it should only be pushed up to the point where it is in forward gear at the lowest throttle advance. When I turn the prop with my foot should the the linkage move?

 

[CharlieB]

Re: 94 135 Mercury going from Neutral to Forward Gear

No, Forward gear engagement is spring loaded inside the gearcase, the linkage simply remove the pressure holding the spring into Neutral or farther, into Reverse. If the linkage does move more it is because the cable is not pulling it all the way and when the engagement dogs align and engage the spring forces the linkage to move that last 1/16 inch.

Shift the control into Forward and mark the linkage travel, disconnect the shift cable and shift the linkage by hand, see any difference now?

The shift cable housing has a teflon lining, over time the cable wire wears a 'groove' on both the inside and outside of every bend in the housing as it pushes and pulls. Once these grooves are worn the actual distance the shift linkage moves is reduced. This limited movement causes incomplete shifting which then causes the engagement dogs on the gears to wear rapidly.

Compare shift linkage movement with the control vs manually shifting with the cable disconnected, when you can see a difference it is time to replace the cable.

 

[Chris1956]

Re: 94 135 Mercury going from Neutral to Forward Gear

Control cables last a long time. Maybe yours is out of adjustment. Set motor to neutral. Remove control cable clamp from shift cable. Now make sure shift lever is centered on neutral detent. Jus wiggle it a bit and let her settle. Now adjust shift cable barrell nut to fit cable clamp. if that doesn't fix it, you may have in issue in the control box or with the shift dog. Do not continue to run it until you fix it, or you will definately need a new shift dog.....