Shift shaft coupling alignment during LU installation 2002 115 hp four stroke

[Capt Harpoon]

I have twin 2002 115 hp Mercury four strokes on my aluminum work boat. When replacing the lower unit on the port engine, I cannot get the shift shaft coupling to line up. It seems to be off to the side so it is not connected. When I start the motor, the LU is in forward, and cannot be changed to another gear. There is no resistance to changing gears at the helm. I am going to drop it down and switch the LU and helm to neutral and try again. Many years ago, on the starboard engine, I had the same issue. My local boat shop drilled two holes in the fiberglass cowling and used needle nose pliers to line them up during installation (this was in a rush; it is a work boat and I had to work the next day). I now have the same issue with the port engine. I do not want to drill holes again unless I have to. What is the secret to getting the upper coupler bushing to align with the shift shaft on the lower unit? What is the correct orientation of the coupling bushing and the plastic guide donut? The donut just seems to sit there on the shelf with the smooth side up. Thanks in advance for your help. CH

 

[Ed27518]

Could it be that it is in fact lining up and that the lower unit shifter is not in the correct position? I had trouble with this on my two stroke mercury and when I put the unit on I could not get it out of forward gear, then I realized the lower unit was not in the correct position, I believe you should be able to put the lower unit in neutral and then put the shifter in neutral to avoid this, there is a page in here on how to correctly put the lower into neutral before putting it back on. Besides that I believe it should line up fairly straight if the lower unit is going in straight. You could try using a ratchet strap to hold the lower unit and help you slowly pull it up while watching closely to make sure it aligns.

 

[Capt Harpoon]

Well, after a bit of work, I got the lower unit installed correctly. I read all the internet advice and watched all the YouTube videos I could find, and none were that much help for this model engine. Half of folks say do it in forward gear, half in neutral. I tried both, several times. In the end, what worked was forward gear. I used grease to hold the plastic donut in place, and a ball point pen to make sure it was centered. I set the shift shaft coupler (Mercury part #43585) with the flange up, if for no other reason that once everything is greased, I could not get a grip on it any other way with my fat fingers. I set the water tube seal (Quicksilver 430232) on the water pump itself, rather than on the water tube. With two sets of hands and a winching strap to bear most of the weight, we finally got it after an hour struggle and several tries. Once everything was lined up, it actually slid together pretty easily, but it was a struggle to get everything lined up. I think the issue was the plastic guide donut. It must be centered exactly, and unless you stick it down with grease, it is easy for it to shift out of place. Glad to have finally have it done and not have to drill holes through the fiberglass like my local boat shop did on the starboard engine years ago.
By the way, what prompted all this was running the engine on the hose and not getting enough water out of the telltale. The water was flowing out of the midsection, and just a bubble or two out of the telltale. I thought it was a bad impeller. It was not. The impeller was fine. It was the water tube seal (430232) which had a split in the lower rubber gasket where the seal meets the water pump outlet.
Hope I have saved someone some help with this problem on the 2002 Mercury 115 hp four stroke.
Cheers,
CH