Rebuilding lower Unit

[Streffpilot]

Hi, I need some help, I am rebuilding the lower unit on my Mercury Thunderbolt 115hp. The serial nuber is 3651920. I was wondering if anyone could come up with the part number for the seal kit, and the bearings.

Any help would be greatly appreciated!

 

[Maxz695]

Re: Rebuilding lower Unit

http://www.marineengine.com/parts/mercury-outboard-parts/ find your model 3 cyl 4 cyl etc etc

 

[Bamaman1]

Re: Rebuilding lower Unit

You're a brave man. Look on UTube to see if they have a video on that. You can find seal replacement videos on some brands.

Lower units are not items you can buy on EbayMotors.com or other web sites from individuals. They must be pressure and vacuum tested by people that really know lower units--preferably a good marine mechanic. Even used, lower units are very, very expensive items. Just a seal kit installed by a mechanic will probably run you over $300. Lower unit gears and washers are really expensive parts.

 

[halmc]

Re: Rebuilding lower Unit

Whether it's feasible to rebuild the lower unit depends on what's wrong with it to start with. If there's mechanical or rust damage to any of the gears, bearings or the shifting mechanism, it's not, it's better to find a used unit, and that's sometimes a roll of the dice. If there's nothing wrong with it and you're just looking to provide it some preventative maintnence, don't do it. Lower units make the case for don't fix it if it ain't baroque.

There's a narrow band of feasibility in which a lower unit that just started leaking fits, where with careful patience and a good deal of skill, you can replace the seals, but it isn't easy. And if it's a salt water engine (a consideration on an '80 engine, even in NW Alabama) chances of prevailing are reduced by about 70% in my experience. One wrung off bolt/screw into an already corroded aluminum casting is for all practical purposes, a dead end.

For me it's just a personal attitude, but when it comes to trusting my ingenuity and motivation versus that of a "good marine mechanic", I man-up and go with me every single time. It generally costs a DIY guy less to screw up something three or four times than it does to pay a professional to screw it up once.

Needless to say, a shop manual is all but essential, no matter how brave you are. Good luck!

 

[Chris1956]

Re: Rebuilding lower Unit

Streff, As was mentioned, special skills and tools are needed to rebuild a gearcase. I would price out the parts you will need and see if you can get a good used gearcase for about that kind of $$.

Where are you located?

 

[Streffpilot]

Re: Rebuilding lower Unit

Thanks all for the concern, I should have specified, I live in Wisconsin, so we have this long non boating season called winter

Also I guess rebuild wasn't quite the right term, I just need to replace the seals. It runs and drives just fine, but I always have a puddle of gear oil under the lower unit while it is out of the water, and instead of toping off the lower unit oil before each outing, i want to replace the seals, and of course the impeller while it is apart. Currently, the motor is on a stand in my (heated) garage, so I have plenty of time to be careful and replace the seals.

How hard is just the seals, and is it possible to do without taking the gears out of the lower unit?

 

[Dukedog]

Re: Rebuilding lower Unit

Your leaking gear oil and NOT gettin' water intrusion in tha gearcase? That usually goes hand in hand..........courious?

 

[Streffpilot]

Re: Rebuilding lower Unit

Im not saying that I dont get water into the lower unit, but when I drain the oil, or it drains itself :/ It is only slightly murkey. It looks like normal used oil.

Like I said, I wont say that No water is getting in there, but i cant difinitvely say that it IS in there.

 

[Dukedog]

Re: Rebuilding lower Unit

I would recommend gettin' an OEM manual first thing. When someone try's to explain how or what ta do on here might not compute between tha two of ya. Especially when it comes to tha gearcase. With tha manual you will be able ta see just how far ya gotta go to accomplish what your wanting ta do. If ya gotta go tha "extra" distance ta fix it, a gearcase is not a "touchy, feely" thing to set up (contrary ta what some folks may say). GL with it.............jmo