Bravo lowers itself overnight...why?
 

A friend of mine has asked me to post the following scenario/question to you tech gurus:
When he puts the boat on his lift, he raises the drive up and leaves it in the raised position. The next day, the drive has lowered itself. Does this mean he has a leak in a cylinder somewhere? Is there a test he can perforn to detemine the problem? Thanks!

It is frustrating...
 

There is a valve in the power trim pump that is causing an internal leak in the system. It could be a liitle piece of debri holding it open or it could be a bad valve. It is a really frustrating thing to fix!!! Find a good Mercruiser mechanic and don't be upset with him if he doesn't fix it right the first time. I am a Mercruiser Master Tech with over thirty years in the business and they still give me fits!
Good Luck
Sincerely
Dennis Moore

I fixed mine myself
 

I removed the hex plugs on either side of the trim pump. There is a tapered plug and spring behind each plug. I had some small black fragments attached to the plug where is seats in the pump housing causing fluid to bypass slowly. I remove the material and no problems ever since. Your friend is most likely having to reset his trim while under-way as this condition is exaggerated with load on the drive.

It's proably the check valve that is leaking. Consider just replacing the pump.

It sounds like the Poppet valves are worn or have dirt keeping them from seating. There is a rebuild kit for the pump that includes the poppet valves and lots of O-rings and small parts. It's a simple job if you follow the directions and keep your working area clean.

For maintenance I usually suck the fluid out of reservoir a couple times a year and clean the reservoir over the winter. Dirt and moisture is what makes these things break.
Dan