merc Lower Unit - can't reinstall

[omegapm]

Hi, I need some help. Never owned an outboard before, never mind an old one. Lower unit froze and cracked so I picked up one from a Mark 58A, they are swappable.<br />I dropped the old one with no problem. The problem I have is that I get the new one in but it doesn't come flush, there's a 1/2 inch gap. I seems to me, a novice, that the shift is stopping it. Now I see that everyone says to put the shift in neutral, which it is, and I saw another post about how to put the lower unit in neutral. which I did. I've wiggled it and jiggled it, nothing seems to work. I know I missing something here.<br />I've been restoring a 1957 Elgin since the spring and finally have a chance to use it this coming weekend. I HAVE to get it done by Friday or wife will kill me.<br />Please help!<br /><br />Thanks,<br />Joe

 

[MartyTn]

Re: merc Lower Unit - can't reinstall

I've replaced lu's on Mk58A types and the books say to put the shifter in forward and leave the lu in forward. I've done it this way several times. Having the shift shaft perfectly aligned is the key. With the lu on the bench, I turn the shift shaft by hand just a little bit clockwise to make sure the unit is in forward gear (when the cam is free with no tension, it's in forward) and then turn the shaft back counter-clockwise until the cam is solidly against the prop shaft. Then I look very carefully at the positions of the shift shaft splines on the lu and on the upper leg to make sure they will be exactly meshed up, and I put a little grease on both of those shift shaft ends. Then I put the lu into place and then make sure the water tube is in place. Then with one hand pushing up on the lu, I slowly rotate the flywheel (always clockwise) to let the driveshaft (with a very light grease coating on top) drop in the splines of the motor. I've had mine off and on so many times I'm even getting fairly quick at it.... Good luck with it,<br /> Marty

 

[omegapm]

Re: merc Lower Unit - can't reinstall

Thanks for the help Marty. I've been wrestling with this for 4 hours now and just came in to check for replies. Maybe my problem is that I have the engine tilted. I actually tried doing this is forward as I read that somewhere else, but again the engine was raised.<br />I'm gonna go outside and throw 2 nuts on it so it doesn't fall off and lower the motor so it's vertical. Maybe that will line up the shift shaft. I appreciate your time!

 

[omegapm]

Re: merc Lower Unit - can't reinstall

Well, I tried what you said Marty and still no luck. What am I missing? you said "make sure the unit is in forward gear (when the cam is free with no tension, it's in forward) and then turn the shaft back counter-clockwise until the cam is solidly against the prop shaft." I'm guessing you mean the shift shaft as opposed to prop shaft. If not, I'm really lost.<br />I pulled this l/u off a 58-A to put on my 55. I've never done this before, never owned an outboat. I thought it would be a simple swap. I have the owner's manual but with all tech manuals, they always leave something out assuming you're not an idiot like me.<br />I have the boat & motor on Long Island and want to use it in VT next week but I'm ready to bury it and tell my wife someone stole it.<br />Any suggestions , anyone, as to what I'm messing up? It's still 1/2" from sitting tight. It's got to be the shift shaft, I turn the prop and I feel the compression so I know the prop shaft is lined up, the water line is in it's hole, but still..... UGHHHHHHH!<br />Time for a short scotch and I'll try again in 10 minutes................<br /><br />Thanks<br />Joe

 

[MartyTn]

Re: merc Lower Unit - can't reinstall

Joe, The way I've gotten it to work is to insert the lu with the engine tilted and then immediately lower the motor to vertical, holding the lu as it goes down, and then start the procedure to engage the shift shaft, etc. And yes, before you put the lu into the motor, turn the shift shaft on the lu clockwise to make sure it's free (in fwd) and then turn it back counter clockwise until it stops (thats when the shift cam contacts the front of the prop shaft). Then look carefully where the splines are on both the lu and on the upper leg of the motor. If the gear shift control is also in fwd, then the splines should be in identical positions. Put some grease on both shift shafts and "wiggle" as you push up on the lu while at the same time slowly rotating the flywheel clockwise, and be sure the water tube is seated correctly in the rubber gromit... When you get everything aligned right it'll slide up so quick you just have to hope you don't pinch your fingers. Also, be sure to have the nuts handy that go on the front studs, you'll fine out that when it goes all the way up, you won't be able to get the nuts on, so you'll need to drop it down just a tad to get the nuts on... Look carefully at those shift shafts and it'll go...

 

[tmcalavy]

Re: merc Lower Unit - can't reinstall

Marty is right on...just take a fair amount of patience and practice to get the Merc LU's back on.

 

[omegapm]

Re: merc Lower Unit - can't reinstall

Thanks Marty,<br /><br />The bolts on the 58-A lu are 1/8 wider than the middle unit holes from the 55 so I drilled them out from the beginning.<br />What I didn't do was pay close attention that the holes were perfectly straight. They were actually at the slightest angle. Once we realized that the unit was binding and corrected the enlarged holes, it slid right in. Stupid mistakes like that often take so much time to figure out.<br />Thanks for your help<br /><br />Joe

 

[MartyTn]

Re: merc Lower Unit - can't reinstall

Good deal Joe, glad you got it bolted up okay. I definitely understand about the mistakes. That's why I've had mine off/on several times -- by not being sure I did something right the first (or second) time, etc.<br /><br />Best of luck with it,<br /> Marty