Lower Unit help please

[gman]

I had some gear oil leaking out of the lower unit from the bearing carrier assembly so I removed it and replaced the seals. After putting everything back together took it out for a ride and now I don't have reverse gear. Any clues as to what I didn't do right? Everything went back together good as far as I can tell. Picked up a manual but it is for a two cylinder 40 h.p. Merc. Mine is a 4 cylinder, 1995 40 h.p. the two cylinder motor has a different style bearing carrier the way it bolts to the lower unit, mine has a nut and washer that screws in on the outer wall of the lower unit. Any help? thanks in advance.

[Priority1]

There is a procedure for pulling these apart. You should have a manual in hand before taking the lower unit off. There is a shift shaft that has to be lined up. I think the upper and lower have to be in forward gear when the units are put back together. If the shift shaft spline is off just a spline or two you can have trouble. Putting things back together that are not properly aligned can sometimes damage parts. Get the proper manual and redo it. I hope there is no damage to the units.:)

[Jason Adam]

Probably need to adjust the shift cable pull/push length. There should be some kind of adjustment at the lower unit itself. I'm not familiar with that lower unit exacatly, but look at you're shift cable adjustment.

[FREEPOP]

Usually what happens is the shifting pawl isn't lined up. It is a shaft that has a u-shaped piece welded to it. You have to make sure it gets lined up when the lower unit is bolted to the upper. It is cadmium gold plated. Loosen th bolts till they are just abot off the bolts and have someone shift it back and forth. It is a common problem when reassembling and you should be able to figure it out when you can see the one half moving back and forth.

[gman]

What I did was take off the prop and then a nut and washer to get to the driveshaft bearing carrier assembly. I pulled this out and there is a rubber O-ring that I replaced that keeps a seal between the gear oil and the outside world. I replaced the o-ring and slid the carrier assembly back over the driveshaft and replaced the nut/washer and then the prop.
I didn't take the lower unit off the motor, sorry for the poor description above and the confusion.

[FREEPOP]

That's okay gman. I have only had the problem when droping the lower unit. Might be a cable issue.

[FREEPOP]

Gman, try and contact Tonga. I believe he's the most knowledgable one on this site. Haven't seen him too much but you may try to PM him.

[TONGA]

If yours is the old 4 cyl gear case then there is what will almost seem like a pushbutton on the front of your prop shaft usually with a spring. The button rides on a cam from the shift shaft, it could be that you have damaged this or it dropped out when you assembled your lower…. one other possibility is that you simply have not pushed the bearing carrier all the way forward you should be able to check prop shaft play front to rear with the prop off. I wont bother you with decimals; lets just say prop shaft movement should be almost non-existent.

[FREEPOP]

Howdy Tonga, haven't seen you here in a while.

[TONGA]

Yea been doing a lot of work in Kentucky over the winter,,and at the moment I am in Florida playing till early next week. Trying to check in when I can, I have just been incredibly busy!

[gman]

things are better now it looks like I didn't have the carrier assembly in far enough. tightened things up some more and pushed the carrier assembly in and now reverse is back. I was hesitant to tightne too much because the nut is plastic and didn't want to break it. things worked good on the wet test in the driveway. hopefully the weather cooperates to take it out on the bay sat. thanks for the help.

[FREEPOP]

I don't know how that goes together but that would concern me. The reason being, if the assembly wasn't tightened you may have gotten water in the lower unit.

[gman]

there was a little bit of water in there so I drained the lower unit and replaced with new gear oil. With the carrier assembly not being pushed in properly the o-ring probably didn't have a good seal. I'm going to run it this weekend (hopefully) and then drain the gear oil again to make sure no water is in it.

[FREEPOP]

Very good idea. Yes o-ring grooves are designed to accept a compressed o-ring. The compression can lessen over time due to it losing it's spring, which is typical of most elastomers, thus allowing leakage. Gear oil is thicker than water (quite obvious) so water will get in before oil gets out. Check the lower unit when warm and you can spot leaks earlier. Also, prior to putting lower grease in, let sit in the sun or put in a bucket of warm water. It will make it a much more enjoyable experience.

I designed parts of the trim units for Mercury / Force / Mariner for serval years. If you have any questions, about that, I may have some ideas for you.