Grinding when shifting forward/ Mercury outboard

[raydabassaholic]

I have a 1991 Mercury Black Max 175 h.p. outboard motor on my bass boat. Ive noticed for awhile now that everytime I shift forward, I hear a little grinding before it kicks in. Just recently, the grinding got louder, longer and when it kicks in its a lot harder. What do I do. The only thing that Ive determined is where the shift cable is in the motor. It runs fine when it kicks in forward and it shifts fine in reverse.

 

[Texasmark]

Re: Grinding when shifting forward/ Mercury outboard

What's your idle rpm? Too fast could aggravate the condition.

Also, might remove remote cable from shifter interconnect on engine and ensure that both move freely and that the remote cable has ample length to put the engine fully in F gear.

When you get it resolved, I'd drain the lower unit for a day or so and maybe flush with a change of fluid and refill it a second time to get the shavings out. A magnetic drain plug will help to capture any metallic shavings in the lube. They may sell them on here. Be sure and use Merc's Premium High Performance lube made especially for the higher hp engines...says so on the container.

The gears in the lower unit are heat treated and extremely durable. Wear usually shows up as an engine that pops out of gear when you hammer down on the throttle.

HTH,

Mark

 

[raydabassaholic]

Re: Grinding when shifting forward/ Mercury outboard

What should be the ideal RPM when in idle? I also noticed that when I started using Stabill in my gas that the idling got faster. I dont know, maybe just a coincidence.

 

[rickdb1boat]

Re: Grinding when shifting forward/ Mercury outboard

Idle should be around 600-700 in gear. If the shift cable is old, then it might not move the shift lever on the engine enough to fully engage forward.

 

[Silvertip]

Re: Grinding when shifting forward/ Mercury outboard

Grinding when shifting into forward or reverse is also caused by shifting too slowly. the grinding is the clutch dogs skipping across each other. Shift with authority. There is no reason to "slide" the lever into gear. Shifting slowly (hence the grinding) means you are wearing things in the lower unit. The resulting clunk you feel as the unit goes into gear is not a problem unless the engine is idling way too fast.

 

[CharlieB]

Re: Grinding when shifting forward/ Mercury outboard

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

Once shifted, disconnect the shift cable and see if the linkage will slide just a bit further into gear. If so, suspect that the shift cable housing is/has worn inside and is not allowing the cable to fully move the linkage.

Replace the cable.

 

[Texasmark]

Re: Grinding when shifting forward/ Mercury outboard

Grinding when shifting into forward or reverse is also caused by shifting too slowly. the grinding is the clutch dogs skipping across each other. Shift with authority. There is no reason to "slide" the lever into gear. Shifting slowly (hence the grinding) means you are wearing things in the lower unit. The resulting clunk you feel as the unit goes into gear is not a problem unless the engine is idling way too fast.

Excellent point that I didn't know about when I got my first boat. Until I realized/learned of, what was taking place in the lower unit with my slow shifting where I didn't know any better.....do now.

Mark

 

[raydabassaholic]

Re: Grinding when shifting forward/ Mercury outboard

Thanks Charlie B, I did what you said about shifting while motor is off and manually spinning the prop and I did notice that the prop doesn't catch in gear until I manually push the cable forward about half an inch and then it finally engages the prop, now the question is , is there an adjustment for that or should the cable just be replaced? And trying to avoid going to the shop, how do I change the cable myself?

 

[Texasmark]

Re: Grinding when shifting forward/ Mercury outboard

Thanks Charlie B, I did what you said about shifting while motor is off and manually spinning the prop and I did notice that the prop doesn't catch in gear until I manually push the cable forward about half an inch and then it finally engages the prop, now the question is , is there an adjustment for that or should the cable just be replaced? And trying to avoid going to the shop, how do I change the cable myself?

The cable at the engine has a hole in the end of the center conductor that attaches to the movable mechanism and also a (brass) barrel which is mounted about 3-6" forward on the outer jacket...cable shield (deadman) inside the engine cowling.

This barrel is threaded and the purpose of it is to be used as a deadman for the cable to operate against, but it also can be run up or down the threads to make happen what we are talking about...shifting adjustments. If that can't get where you want to get, there is another in the control box just like it and together you should be able to get what you need for a good solid shift.

Mark

 

[CharlieB]

Re: Grinding when shifting forward/ Mercury outboard

Ig you mean that you were turning the prop while a helper shifted the control and the drive DID NOT lock into gear until you pushed the linkage forward, then the cable housing is indeed worn, and not forcing the cable to pull the correct length.

Cable replacement is pretty straight forward, disconnect the cable and housing from the motor, the control box needs to come loose to remove the back plate and disconnect the shift cable.

Remove the cable from the boat, note how well zip ties are used to hold it into place as you will want to secure the new cable close to the same.

The cable will have #'s inl stamped into the housing near one end, your parts place will need these to get you a replacement assy.

Reinstall the new cable to the control box first, with the control remounted and in Neutral, attach the motor end and adjust so fit in Neutral.

Again, have a helper shift the control while you turn the prop to check shifting both Forward, Neutral, and Reverse. You may have to make slight adjustment to the cable to lock both Forward and Neutral.

 

[raydabassaholic]

Re: Grinding when shifting forward/ Mercury outboard

Thanks fellows, i will try adjusting it first and if that doesn't succeed then I will replace the cable, thanks again for the quick response.