Lower unit stuck: 1986 50hp Merc 3cyl

[PJSuburby]

Hi, I'm trying my first water pump service on a 1986 3cyl 50hp Merc ser# 0b343304.<br /> I *think* I have all nuts loosened. 2 on sides, 2 bottom and it can be moved about a 1/8inch down but that's it! Is it usual to need to put some heavy pulling muscle on it? I can't bear to put a screwdriver in there and wedge it down,looks like I'll only tear up the metal. It's a perfect seal right now and I know little, but just enough to NOT pry it. Any ideas? Am I missing a nut somewhere? What's the trick to stubborn lower unit removal? Sealoc manual shows only what I've seen.<br />Thanks for any ideas.<br />Pat

 

[Stefan Schmitt]

Re: Lower unit stuck: 1986 50hp Merc 3cyl

I'm an outboard newbie myself..but I'm having the same problem. Do a search on "lower unit" and you will find many different scenarios. First off though: check your manual.<br /><br />The most likely scenario probably is that your drive shaft and/or the gear shaft splines are fused, corroded, or just stuck together. I've read about everything from using wedges, liquid wrench/WD40, to turning the outboard upside down and filling those areas up with liquid wrench/diesel/oil to loosen the splines. Your pick...<br /><br />...oh yes, please everyone chime in with suggestions! I could use them myself.

 

[PJSuburby]

Re: Lower unit stuck: 1986 50hp Merc 3cyl

Dr Bones,<br />Thanks for the "search" ideas. It's all here when you're pointed in the right direction!! The wedges sound good, along with penetrating oil ideas.The lower unit was off by a mechanic 3 years ago and has not seen water since. I bought it and know it needs a full serice before getting wet.<br />It loves foreward gear and stays there. The cables are good and move smoothly when detached from the motor, so I have to get the lower unit off, hoping it's something easy to fix down there (yeah, sure)<br /> I can't check compression until I can get it OUT of gear. <br />Thanks,<br />Pat

 

[andrewkafp]

Re: Lower unit stuck: 1986 50hp Merc 3cyl

You need to leave the bolts in, but loosened and whack the cavitation plate with something that won't scratch or bend anything.(Wood is good) If the mechanic did his job right, he would have lubricated the splines on the driveshaft, so it should come off.<br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=29;t=008642

 

[rexa1925]

Re: Lower unit stuck: 1986 50hp Merc 3cyl

Need to look closer becouse you R missing 1!<br />I can tell you where but just look and when you find You will not forget the nest time.<br />If not just e-mail me<br />Rexh1954@aol.com<br />Good Luck<br />Rex A.

 

[jim dozier]

Re: Lower unit stuck: 1986 50hp Merc 3cyl

I don't know exactly how Mercury connects the shift linkage in the lower unit, but check to see if it needs disconnecting. The fact that you got it apart 1/8 inch sounds like the shift linkage is still connected.

 

[PJSuburby]

Re: Lower unit stuck: 1986 50hp Merc 3cyl

Unicorn,<br /> You're right. A Whack on the plate and it dropped another inch, then came off easily.There were only the 4 nuts. The mechanic of 3 yrs ago must have been a good one, splines were well lubed and stainless shaft looks new.<br /><br />NOW, while I'm doing the water pump service, I want to run a compression check.<br /><br />Can I run the compression check while the lower unit is off? or will I damage something? <br />The motor finally went out of it's locked up foreward gear to shifting easily after the lower unit was loosened. Does that mean there is trouble ahead?<br />Thanks EVERYONE for the help.<br />Great forum.<br />Thanks

 

[andrewkafp]

Re: Lower unit stuck: 1986 50hp Merc 3cyl

Well done <br />I'd say you could do the Comp test with L/U off, but you might have trouble getting it lined up when you are putting it back on. I would do the pump first and replace everything, then comp test it after you complete that project. See whether the veterans agree <br />The shift linkage may have been in need of adjustment and after you dropped the leg, the resistance is gone. That sounds more like the problem rather than damaged gears to me..

 

[jim dozier]

Re: Lower unit stuck: 1986 50hp Merc 3cyl

There's no reason you can't do a compression test with the leg off. You might have to rotate the flywheel a tad to line up the splines on the drive shaft when you put the lower unit back on. But you would probably have to do that anyway.

 

[PJSuburby]

Re: Lower unit stuck: 1986 50hp Merc 3cyl

Thanks, I got the complete water pump kit today from a local mechanic that suggested I check the "lockout" also for binding as a cause of no shifting. Whatever that is, need to find that.<br />It's Great to hear I can check compression without the lower unit OFF. If compression is bad, then I know where I stand, in poop. Otherwise I may have an operational 50 Merc soon!