Bravo X1 Drive Erratic Trim Operation
 

My 2004 Bravo X1 Drive when trimming up or down shudders, has slip stick type of movement. It did not used to do this. It has about 380 hours on it. The fluid reservoir is full and the drive shaft spline is fully lubbed. The merc tech line says to do a pressure test on the pump system.

I am interested in hearing if anyone has experienced this symptom and what was the cause/fix.

Pull the rams off of the drive and work them in and out and see if they extend/retract smoothly with no load.

check the coupler alignment with an alignment tool make sure the motor mounts are tight and true'

did this just start out of no ware or was there some servic done ?

I had pulled the drive and engine 162 hours ago and reassembled with an alignment tool then. I will check the motor mounts as you suggest.

Yes out of no where but it has been doing it for a little while now. I was not sure if it was normal or not but finally decided to take action. No service has been done on the trim since the boat was new.

I will do that.

Rage- I had that problem on my port drive once. I was advised to drain the oil, refill and purge. I did them both and it solved the problem, boar was only 6 years old.

The electrical connections were all good. I disconnected the cylinders from the drive so no load. The pump would randomly labor at different levels of strain as the cylinders were trimmed out or in. The cylinders took turns sticking, shuddering or conversly running smoothly. Sometimes the cylinders would just stop and the pump would stall completely. Sometimes if I would release the trim button and immediately reapply everything started again to work correct....only briefly.

is the boat stored on a lift?? weve seen trim ram wiper seals corrode and pistons would stick. believe it or not, less problems when the drive is in salt water continuously rather than water then air so forth

Yes on a lift since 2005. What do you mean the wiper seals corrode? They are rubber or plastic right? Please elaborate.

well the end caps have rubber seals but on the outside closest to the water is a steel ring that protects the rubber o-rings. the end caps are aluminum so the constant water/air exposure and dissimilar metals causes corrosion and this white crud to form which sometimes makes it hard for the piston to move. just a thought. good luck

This sounds like good advise. Bill, Lets us know what you find out.

Thanks for the thoughtfull brainstorming and suggestions.

Yesterday's testing with both cylinders disconnected from the drive and therefore operating at no load with the drive (and sensors) at the full down position and now static would seem to take the electrics mostly out of it. Also the pump would still randomly labor at different levels indicating load/strain on the fluid pump as the cylinders were trimmed out or in. The cylinders took turns sticking, shuddering or conversly running smoothly. Sometimes both cylinders would just stop as the pump would stall completely. Sometimes on these occasions if I would release the trim button and immediately reapply everything started again to work correct....only briefly. The sounds the trim motor made during this testing versus the movement, or lack there of, was like the fluid resistance was overloading the pump motor as apposed to intermitant electrical connection problems.

I would like to hear about the potential hydraulic reasons and or fixes for my trim issue that you may be aware of. I have so far heard that dirty fluid could be the cause and a simple fluid change may fix the problem. Also suggested was that the trim cylinder piston seal (seals?) seperating the up pressure side from the down pressure side of the cylinder could be bad/leaking. Corrosion build up between the of the aluminum trim cylinder body and stainless steel ram shaft (I checked mine and clear). Your thoughts experience versus these or other causes?

After your done prop testing for the year I would pull one ram completely from the boat and disconnect the hydraulic lines. Then manually cycle the ram, feeling for resistence inside the ram. If something sticks, pull the endcap and remove the guts for inspection. They come apart really easy. After the anodes are removed you will need an adjustable spanner wrench with two .250 dia dowel pins.

Good idea. I will do that when I go to remove the trim cylinders and pump this weekend to take back home for inspection and repair this winter

just a side note - the corrosion on the end caps CANT be seen from the outside. They have to be removed to check/repair. JD

Rage- Just a thought, have you cleaned all conections and changed the fuses? You may have a voltage drop issue due to a bad connection. Try operating with a volt meter on the pump and see what you have when it stalls and studders.

Good idea.

I disassembled everything on the power trim hydraulics (only). There was about an 1/8" layer of tiny black dust like particles in the reservoir. Then I found larger ~1/16" particles in various places in the trim pump manifold passages where there should not have been anything but fluid. When I evacuated fluid from the cylinders those same larger black particles came out. There is a black 1/2" thick crescent shaped plastic spacer that snaps on to the trim cylinder ram shaft. Well one cylinder had one and the other one did not except for that portion that was crammed into the three pressure relief check valves in the piston. Apparently the one plastic spacer completely disintegrated and contaminated everything with its residue. The seals all look excellent. The pump's two fluid hose connection fittings have a fine mesh screen welded/brazed to the fitting. The one fitting's screen was still good but the other screen had apparently been blown off by the fluid pressure against the screen when it was plugged with the plastic residue. That screen was still attached on one corner. That is how the residue got into the trim pump manifold.