94 135 Merc Lower Unit Noise Please Help

[Alpinegold]

I have read the articles on the forum but have not found an issue exactly like mine. My 135 Mercury on my Procraft has always ran good. I am having an issue with my lower unit.

When I shift from neutral to forward, and give it some gas I get a pretty hard knock or thump sound , bout 3 maybe 4 bumps before she comes up to plane. No issues after that except when I have to go back to neutral and do they same thing. I do not recall that this happens going into reverse.

Reading some of the other articles, I see this problem frequently when going from neutral to reverse but mine is just the opposite. I have not noticed any problems with the control box shift arm being hard to move in any direction.

Could this still be a cable adjustment issue? I'm a little short on cash and need to see if there is anything i can do for it.

Thanks for any suggestions.

 

[CharlieB]

Re: 94 135 Merc Lower Unit Noise Please Help

It is possible that your shift cable has stretched just enough that it is not being pulled completely into gear.

You may try re-adjusting the shift cable just 2 or 3 turns and see if that improves the condition. If so, plane on replacing the cable in the very near future because the more you adjust towards 'Forward' the less movement you will have into 'Reverse' and you do NOT want to damage the shift slider, rounding off the edges of the engagement dogs.

 

[Chris1956]

Re: 94 135 Merc Lower Unit Noise Please Help

First check the shift cable adjustment. Remove the latch that holds the shift cable barrel, and with the motor in neutral and the control in neutral, see if the barel is adjusted to center in the holder.

If that is OK, perhaps you have a bad prop hub. Alos check/change the LU gear oil.

 

[Texasmark]

Re: 94 135 Merc Lower Unit Noise Please Help

Along with what Chris said, an expansion of that:

I'd remove the cable from the holder/shift slide at the engine. Get some help. By having someone turn the prop, move the shifter slide end to end and mark the location on the shifter slide where you come out of F gear and go into R gear, or vice versa. (See R caution below)
Mark the half way point and then position the slide to that position.

Reinstall your cables and work your shifter at the control box. Remember R has no overrun clutch so you have to move slowly into R and have someone rotate the prop by hand to get the R finger-sockets to line up. Once you get R lined up and don't rotate the engine or prop you should be able to go back and forth in the next step.

Find N on the control box after you have moved back and forth (FNR RNF FNR kind of thing) several times. Now check the position of the shifter slide in the engine. If it's not centered on the mark you made for N adjust your cables till it is. (I would expect that it is not where it should be.) If you don't have a damaged clutch dog in the lower unit, your problem should disappear.

HTH

Mark