91 Force 120 trim motor rebuild?

[AHillman]

Hello to those smarter than me.

I purchased a 19 foot Bayliner last summer with a 91 Force 120 on it and the motor settled from the get go, figured I could get it cheap and fix it. I thought I would just have to rebuild the cylinders and it would be good to go but that wasn't the case it still settles. The weird thing is it settles only about half way then it stops and I can stand on it then but in the water powering for a while it will go all the way to the bottom. My question is would rebuilding the pump fix it, how hard is it to rebuild a trim pump, and is there a service I can send it into to have it done for less than the cost of an arm and a leg? I remember coming upon someone here that rebuilds them but I don't remember his screen name?

Thanks in advance.

 

[joshackley]

Re: 91 Force 120 trim motor rebuild?

I'd be interested in an answer to this too. It seems my trim pump has decided to act up. It works fine for a while, trims up and down like it should, then all of a sudden it just stops working. Give it a few minutes, and it'll work for a little bit longer, then stops working again. Can still hear the relay click, just no movement.

 

[MickLovin]

Re: 91 Force 120 trim motor rebuild?

Josh, yours sounds like an electrical problem with the motor itself, but AHillman, yours sounds like a hydraulic problem. I am not right up on these trim/tilt motors, but the pump of mine is only the bottom part which is held by 4 s/s screws, the reservoir is bolted to the outboard frame and the motor is bolted to the top of the reservoir with two bolts going through the motor into the reservoir.
I take it you have a tilt ram and a trim ram? So it would make sense that you are either having a problem with the trim ram OR the actual pump not releasing properly. You can just buy the pump (valve body) but be careful when taking out or screwing in the s/s hydraulic hoses, you can easily cross thread these and once they leak your up for another pump. Have you checked your hydraulic oil level in the reservoir? Before buying a new pump and probably spending up to $200, send this post some pictures or even a video of it working.

 

[joshackley]

Re: 91 Force 120 trim motor rebuild?

Josh, yours sounds like an electrical problem with the motor itself, but AHillman, yours sounds like a hydraulic problem. I am not right up on these trim/tilt motors, but the pump of mine is only the bottom part which is held by 4 s/s screws, the reservoir is bolted to the outboard frame and the motor is bolted to the top of the reservoir with two bolts going through the motor into the reservoir.
I take it you have a tilt ram and a trim ram? So it would make sense that you are either having a problem with the trim ram OR the actual pump not releasing properly. You can just buy the pump (valve body) but be careful when taking out or screwing in the s/s hydraulic hoses, you can easily cross thread these and once they leak your up for another pump. Have you checked your hydraulic oil level in the reservoir? Before buying a new pump and probably spending up to $200, send this post some pictures or even a video of it working.

Thanks Mick. I went and tested it again a little while ago. Same thing, starts going up/down, and then slows rapidly to a stop. I'm thinking perhaps it's the pump. All the electrical seems to be working fine? Didn't mean to hijack the thread, so my apologies. I thought perhaps that our problems were similar.

 

[Jiggz]

Re: 91 Force 120 trim motor rebuild?

AHillman, the Tilt and Trim guru in here is RRitt. With the simple diagnose you provided, it is very possible your problem is worn out O-rings on the the hex check valves in the valve body (VB). If you can post a pic of the valve body, it will make it easier to give you instructions on how to remove the check valves and replace the o-ring. It is really not that hard but you also have the option of having it done by RRitt who I believe still does VB rebuilding.