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BF 90 Lower Unit

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billyrube

New member
I have a lower unit from a BF 90 that turned fine 2 months ago, now it is seized. I removed the lower unit and removed the water pump housing and top cover exposing the main bearing on the driveshaft. The bearing looks oxidized and there is signs of salt intrusion across the gasket and the seal looks questionable. I notice it shifts and the prop shaft turns smoothly when in neutral.

I think its just the upper bearing thats locked up, but I cannot see how it comes out. If I can replace the bearing without tearing the entire lower unit apart I will. Otherwise I will take it to a shop. Any ideas? Can I just remove the vertical mechanism? How does it come apart??

Thank-you for an assistance!!
 
Depending on the year of your motor, you have to remove the water pump, then the shift shaft #10, then remove the propshaft housing, then the pinion nut #29 to remove the vertical shaft. While the lower unit is apart, it should be resealed and a new water pump kit should be installed.

http://www.boats.net/parts/search/H...0A3 LRTA/WATER PUMP VERTICAL SHAFT/parts.html

http://www.boats.net/parts/search/H...0A3 LRTA/PROPELLER SHAFT PROPELLER/parts.html

If you are going to do it yourself, I highly recommend you buy an official Honda shop manual.
http://www.amazon.com/gp/aag/main?i...=ATVPDKIKX0DER&orderID=&seller=A14VJQOXKKYWSY

Mike
 
hondadude, I have disassembled the lower unit. I have the pinion nut removed, now how does the pinion gear come off? Its either stuck or I'm doing something wrong. Your thoughts and thank-you!
 
The pinion gear should come off as you remove the vertical shaft. If the lower unit has a metal water pump housing, it is the Mercury unit and I think you just have to pull up the vertical shaft. It may take some creative force.

If you have the water pump that has the plastic housing, there is a nut at the top of the shaft that has to come off before you can pull the vertical shaft out.

In any case, it is probably going to be challenging since it was seized. You may have to use generous amounts of PB Blaster sitting in that area for a few days before it will move.

Mike
 
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