bow thruster repair

[simbo]

i purchased a twenty year old, 24 foot minitrawler this past August. It came equipped with a Volvo Penta QL BP450 bow thruster which was a joy to use until it quite working.
The unit's electric motor still works but the drive gear needs an overhaul.
To date I have removed the electric motor and the two props on the drive unit along with the gears that drive them - easy enough. Both gears I removed are partially stripped and obviously need replacing - no big problem. What remains is the tunnel with the motor mount attached along with the upper part of the drive unit which penetrates into the tunnel. Imagine an inverted tee hanging down into the tunnel.
My problem now is as follows. How do I remove the motor mount from the tunnel so that I can get at, remove and service the upper portion of the drive unit?
I have carefully studied the schematic but am currently stumped.
simbo <span style="color:black"> </span>

 

[Boathook]

My vetus unit gearbox was 'bolted' from inside the boat. The base holding the bolts inside also having the electric motor fitted to it. I assume that there are no visible bolts/screws that clamp the 2 parts together either of the tunnel?

 

[spannerman]

Under the motor in the section that sits on the tunnel are two bolts or allen screws, remove these and the gearbox section will push out into the tunnel. Use a new gasket and sikaflex when replacing, and fill the gearbox with oil before refitting as it is tricky to get the air out when its installed.

 

[simbo]

I have already removed the two long allen head screws you mention. When I now look down on the motor mount I see the upper end of the drive shaft inside a bearing. A circlip and another clip hold the bearing and shaft in position.
Do I now remove the two clips - one holding the bearing and the other holding the shaft or do I push the entire unit down?
Is the motor mount permanently attached to the tunnel?
Thanks for your quick response and interest in helping me.

 

[spannerman]

Just push the entire unit down into the tunnel, it might hang up a bit from the silicone used to seal it but it does go out that way.

 

[simbo]

hey spannerman,
I will try your advice of just pushing down on the entire drive unit when I go out to the boat this weekend.
I am still wondering how the motor mount is connected to the tunnel?
Thank you for sharing your knowledge.
Simbo

 

[simbo]

hello spannerman;
Using the info you gave me, I successfully removed the drive unit from the tunnel of my bow thruster. The remaining mystery I am trying to solve is how to get access to the inside of the drive unit so I can replace the seal(s) and bearings. I see a small line on the main housing right above where it seals against the tunnel wall. Does the shaft unscrew here?
Simbo