Mercruiser Pre Alpha Trim Issues

[ffederman]

Have a 1974 Sea Ray. Trim pump is the all metal version. My rams go up but not down. The motor does run when trying to lower rams. My next move is to reverse the hydraulic lines at the pump to see if the rams will go down, thereby hopefully eliminating the rams as the problem. If the rams do go down with the lines reversed I was going to remove and clean the appropriate check valve.
Two questions. Is my approach wrong? If not, any information on identifying and servicing check valves would be appreciated. Thanks

 

[Bt Doctur]

Be very carefull working on the check valves. Count the number of turns to remove them , clean the components, and install them in the reverse order correctly.

 

[wahlejim]

I have an MC-1 pre alpha power trim as well. I have run into the same issue. Do your hydraulic lines that connect to the ram connect near each other or on opposite sides of the ram? If they connect near each other, there could be internal leaking in the ram, which is the issue that I ran into. Otherwise depending on the model of pump that you have, the valve control body with the the check valves could be mounted on the outside of the reservoir or the inside. Determine which model you have. I found these links to be helpful..

http://www.boatinfo.no/lib/mercruiser/manuals/mercruiser4.html#/14

http://www.boatfix.com/merc/Servmanl/6/6C1R3.PDF

http://web.cemr.wvu.edu/~mathews/boat/pdf/manual/Chapter Eighteen.PDF

 

[ffederman]

Thanks for both responses. My rams connect next to each other on the aft side. The third link you provided is the correct one. I guess I have to remove the pump from the reservoir to expose the check valves?

 

[wahlejim]

I had the external mounted valve control body and just replaced that, if yours is internal, then yes. Just a side note, I went through the process of replacing the valve controls and it was still giving me issue. It ended up being an internal leak in the rams. Do the rams slowly lower on their own? Are the rams binding up anywhere? while you have the oil drained, take the rams off and see if they slide freely in both directions. They should without any oil pressure behind them. if they don't, time to rebuild or replace them.