Need help with trim system diag.

[gulfvet]

I have a merc 898 outdrive that is bleeding off pressure when i leave it trimmed half way up. When i trim it all the way up it stays put. I had a reverse lockout valve that was leaking and thought it was the problem, but after replacing the o-rings in the valve I still have the same problem. I have checked for leaks and have none. The pump is a Prestolite single solenoid. Are there check balls in the pump that fluid might be leaking past?I just don't know where to start. I have gone over the troubleshooting tree for merc trim systems, but I don't have the gauges and such to do it right. Any suggestions would be appreciated.Thanks!

 

[achris]

Re: Need help with trim system diag.

2 possible places for an internal leak. One is the rams themselves, the other are the check valves in the pump body. Those check valves are balls, yes. If the problem was the pump the drive would leak down from any position. As it does not happen at full UP, the I suspect up may have some damage or scoring inside one or both rams. That would be my first check...

The repair kit (part # -45522A3) for the series 1 rams includes the internal sleeve so if the rams are the problem, then a kit will fix it. Remember to change the 'O' ring at the bottom of the cylinder....

Chris.....

 

[gulfvet]

Re: Need help with trim system diag.

Thanks achris. I suspected the rams might need a re-build. I just got done re-storing the boat and it has not been used in 10 years. I will have to re-build those this winter. Thanks again.

 

[achris]

Re: Need help with trim system diag.

Do both hoses go into the ram at the forward end (Series 1) or does one of the hoses run (as a stainless tube) up the inside and enter at the aft end of the ram (Series 2)?

 

[gulfvet]

Re: Need help with trim system diag.

both hoses go into the end. I don't remember which one is up or down.

 

[Don S]

Re: Need help with trim system diag.

 

[achris]

Re: Need help with trim system diag.

Doesn't matter which hose is which, just as long as you put them back the way they were. You have series 1 rams and they are easy to rebuild.