1998 Honda BF90 PTT removal

[RoGun_Mako171]

I'm trying to remove the Power Trim and Tilt from my engine to rebuild it because seals are leaking. The lower cylinder collar seems to be fixed by the bushings and won't move more than a millimeter or so. Was hoping I could wiggle it out of the stern brackets, but can't get past the lower cylinder collar. So that lead me here to ask if anyone has experience with removing the PTT on a 1998 Honda BF90. Do I need to pull the engine so I can disassemble the stern brackets/swivel case to remove the PTT or should I be able to remove the PTT with the engine in place?

 

[ahicks]

You need to have the engine on a lift as you need to remove the weight from the transom mounting brackets. The plan is to get one side off (transom mounting brkt.). That should allow you to remove that PTT assembly with a minimum amount of dissaembly.

With the boat on a trailer, it may be possible to lower the front of the boat, block the bottom of the motor (skeg) then raise the front of the boat to remove the weight from the transom, allowing you to get one side off.

Best of luck on your rebuild. Interested in hearing how you make out.

 

[RoGun_Mako171]

Thanks for the advice ahicks. I will try a combination of blocking and hanging from the rafters to relieve the weight from the pivot point of the stern bracket so I can remove the port side of the bracket and get the PTT off. After doing some rigging and re-rigging, it looks like I will need to have the engine trimmed relatively low so I can target the center of gravity with the strap and come along, but not too low that I can't remove the PTT. I'll let you know how it goes.

 

[ahicks]

Seems like I'm messing with this kind of thing often enough where I can justify the space required by a cherry picker in my very compact shop/garage. I bought the 1/2 ton version for 100 bucks or something on sale at Harbor freight. It's perfect for this job. There's 400 lbs. in play here. It's NOT something you're going to muscle around by yourself if it gets sideways on you. Be careful!

 

[RoGun_Mako171]

Thank you for the words of wisdom ahicks, my rigging worked and the engine is very stable. I removed the port side of the stern bracket and have the PTT off and am in the process of rebuilding it, but am wondering how on earth to remove the free piston. The service manual says to put 1oz of fluid in the main cylinder before pushing in the free piston, but never mentions how to get the free piston out. Do you have any advice on removing the free piston? I wish I had thought about it more and used the motor to push it out before disassembling. I tried a strong magnet, but will not budge before the magnet releases. There is nothing else to grab on to yank it out of there. No bolts to take out to push from the bottom either. So I'm thinking I may have to put it back together and see if I can bleed all of the air out and leave the old o-ring and backup ring on the free piston. If not, I'll try to use the motor to push out the free piston.

 

[ahicks]

In my younger years I used to mess with shock valving on quads, bikes, and snowmobiles. So wile I can appreciate what you are doing, to be honest never stuck my nose in there. Have been lucky to date. My PTT issues generally involve salt water (corrosion) so I generally need to replace them.

Using the motor to (CAREFULLY) push that piston out sounds like a good plan to me! -Al

 

[RoGun_Mako171]

Success! I was able to bleed all of the air out without removing the free piston and all of the cylinders work properly. We're ready for the water again this weekend. I appreciate your help Al, you saved me a lot of time and potential aggravation.

Thank you,
Ron

 

[ahicks]

Love it when a plan works out. Thanks for the update! -Al