pulling off lower unit

[joshdashnaw]

I've gone through and read some threads on lower units, but still have some questions. Do I need to drain any gear oil out before I pull it off or is it a sealed inside there. I should probably change the gear oil either way. I noticed three screw on the unit. A lower that looks like where I would drain it, and two up top one saying vent and one fill. Is there anything else I should know about changing the oil. I pulling the lower unit to look at the water pump. I plan on changing the impeller, but what else should I look for to replace. What to look for to tell if the whole pump itself needs replacing. I have gotten a lot done with the help of all of you, and now I'm almost ready to take the boat out.

 

[skibug]

Re: pulling off lower unit

Yes, go ahead and drain the oil. Unscrew the top plug and then undo the bottom plug. And when you refill it's best to fill from the bottom up. They make special lower unit fill kits. You can pick one up at Walmart. It's best to fill from the bottom with the top plug out, that way you fill up any air pockets as the oil is filled.

Go buy a water pump kit and replace everything you can while in there. If you have never done it, it is always a good thing to do and you always know when it was last done.

 

[valencehsift]

Re: pulling off lower unit

Agreed, if you have the lower unit off, replace everything. Make sure to lightly grease the impeller housing, and make sure the veins go in the same direction. You will notice that the impeller is slightly oversized and off center, that is normal. Good luck.

 

[steamplant]

Re: pulling off lower unit

Check out this website for a drawing of your lower unit
http://www.mercruiserparts.com/

I changed out my lower unit last year, it was recommended to me by this website to get some 4" long threaded rod to help guide the unit when going back together, it made my life a lot easier. I have a 1985 85 HP force. Good luck