Merc 115 Very Weak in Reverse

[Danny C]

I have an '83 mercury 115 tower of power. Ran fine last year. I winterized it last year (fogged the carbs and cylinder). I went the leave tank full with stabilizer route. Have not replaced LU lube yet. Boat fired up and ran fine on the muffs. Took it on the water today. Neutral and forward run ok but reverse is weak to non existant. When I put it in reverse it sounds rough (almost a grinding gear, maybe not going into gear al the way?) The prop will run in reverse but it had basically no power to move the boat back. Any thoughts? I am a pretty capable handyman...how big of a job is taking the LU off to investigate.

Thanks and happy boating,
D

 

[Laddies]

Re: Merc 115 Very Weak in Reverse

The shift cable has a bind in it make sure it's not kinked and if it's OK adjust the cable to push it into reverse a little more 2 to 3 turns should do it.

 

[Danny C]

Re: Merc 115 Very Weak in Reverse

Thanks Laddies.

I was going to adjust the shifter cable but before I adjusted anything I checked prop rotation. In forward it ratchets clockwise and locks counter. neutral is free both directions. reverse ratchets each way. not easily, but definitely not locked both ways like I believe it should be. Does this point to gears not locking? Also, I ran it on muffs, and it seems to spins fine in reverse, but I am guessing once any resistance is put on the prop (i.e. in the water) it will slip. I didn't feel like sticking my hand in the prop to find out...

 

[Laddies]

Re: Merc 115 Very Weak in Reverse

Just adjust it toward rev and it shuld be fine

 

[Danny C]

Re: Merc 115 Very Weak in Reverse

So I spent all last sunday adjusting my shifter cable. After multiple trials, I actually ground down the barrel nut to get more turns out of it. I have it like 10 turns to reverse (as much as possible) and it still ratchets both ways. I unhooked the shifter cable and manually bushed it into reverse and same thing. cannot go back further. Also, I noticed that in neutral, if I bump the throttle forward, the prop will engage in drive before I actually push it into drive. So that would point to the whole cable being off a little, but it was fine last summer and I am 10 turns further in revers and same thing. Is there somewhere internal to the motor/LU that could have slipped out of adjustment?

Thanks for the help,
D

 

[Laddies]

Re: Merc 115 Very Weak in Reverse

Sounds like the upper shift shaft is twisted, usaully caused by shifting into reverse without the engine running or some one turning the prop. Drop the unit down and see if it shifts when off the engine and if it does the shaft is twisted.

 

[Danny C]

Re: Merc 115 Very Weak in Reverse

Thanks, Laddies. Is that the linkage that is directly connected the shifter rod/cable that is reachable under the cowling? Hard to replace? Also, before I buy a new one, is there a way to tell if it is twisted (is it obvious) if I remove it and take a look? Do you think a local Marine parts store carry this or should would I most likely have to order?

 

[Laddies]

Re: Merc 115 Very Weak in Reverse

Yes, it requires the power head to be removed, when we were still in business we stocked the common ones and your engine falls in that group. you can see the twist normally, you need a jig or lower shift rod in a vise and compare the position of the top lever to tell for positive. If the engine will not go into rev gear without the shift cable hooked up and it will shift when the lower unit is removed, the upper shaft is the only thing in between. If the unit will not go into rev when it's seperated fom the engine then either the shift dog is bad of the carrier is pushed back or loose. If a engine has been run not locking into rev where the clutch dog has been racheting it can damage the clutch dog and reverse gear, so if you have to use the boat don't use rev gear.

 

[Danny C]

Re: Merc 115 Very Weak in Reverse

So pulling the powerhead scared me off. I took it to a mechanic and he says water froze in the LU causing the bearing carrier to be pushed back and crack. I took a look and it was cracked (not too badly) and the dog was worn a little bit and some pin looking thing (about 1/2" diameter) that was supposed to come to a point was rounded off. He is basically saying he cannot get a replacement carrier and the gear should be replaced (little wear). He has a replacement LU sitting around his shop from when he replaced it with a jet pump for someone. That LU looks worse than mine on the outside but he says it should work. He wants $400 for it or $500 is he installs it and replaces the gear lube. Does that sound like a good price? I am a bit worried that I would be paying $500 for a LU that is in about the same shape as mine. I am thinking about asking for him to just pull the bearing carrier and out of his and replace mine. Any advice?

 

[Laddies]

Re: Merc 115 Very Weak in Reverse

Thats hard to say if his unit has been pressure tested and comes with some type of warrenty then you should not have to worry but if don't I would look around a little. There must be some used carriers and gears out there some where.

 

[Laddies]

Re: Merc 115 Very Weak in Reverse

I can't believe I did not tell you to check the carrier, I must be to old for this, anyway there are carriers on ebay. Here's a couple.
Mercury Outboard Carrier 650 thru 1500 52132A 1 52132A1 | eBay
52132A 1 Bearing Carrier Assembly Mercury 650 4 Cyl | eBay