Merc Trim Pump Questions

[Sugo]

While repairing a boat I purchased I noticed the trim fluid was a bit milky in the reservoir. (Mercruiser) I tried running the trim down then up. It stopped mid travel on the way up. Now the solenoids clicks in both direction but that's all. The pump is not engaging. Where should I start? Can I unhook the pump wiring and apply power directly to the pump motor to determine if it is the pump or a connection. If it turns out to be a connection. Then how do I go about flushing out the milky fluid and finding where the water came from. I am guessing my situation is not unique. There must be a common spot where it leaks, (maybe where the lines connect to the rams? ) I can't seem to find the answers from the other posts. Any tips for these uncharted waters would be much appreciated.

 

[achris]

Re: Merc Trim Pump Questions

Apart from "Mercruiser" what exactly are you working on? We like serial numbers if possible, but definitely year and model (of the engine NOT the boat).... Without this information we are shooting blind...

 

[Sugo]

Re: Merc Trim Pump Questions

It is a 1994, 4.3L with a alpha one out drive. It is in a 19ft Bayliner

 

[Don S]

Re: Merc Trim Pump Questions

It's an Alpha I Gen II. Here is the troubleshooting charts.

View attachment A1G2 Trim Troublelshooting.pdf

 

[Sugo]

Re: Merc Trim Pump Questions

I posted a bit too soon. Things became a bit more clear after removing the pump, taking it apart and understanding how it works. After cleaning up the brushes, the windings and the armature the pump motor came back to life. I flushed out the milky oil from the rams, the lines and the reservoir and it seems to work fine. I could not figure out how to separate the pump housing from the reservoir, I believe there is still a leaky seal on the bottom side of the pump housing as I found signs of milky oil on the end of the motor shaft. The motor has easy access so I can revisit that seal later. I will keep my eye open for leaking oil to try to find out were the water came from. I suspect the seals on the rams themselves are the culprits. Should be good for this season and I will keep my eve out for a reasonably priced replacement. Thanks for the chart.

 

[ktbarrentine]

Re: Merc Trim Pump Questions

I could not figure out how to separate the pump housing from the reservoir, I believe there is still a leaky seal on the bottom side of the pump housing as I found signs of milky oil on the end of the motor shaft.

If your reservoir is like mine (which it looks like based on the exploded diagram for your pump), the reservoir is held to the bottom of the pump by a screw and o-ring seal that penetrates the bottom of the reservoir (poor design, so they changed it). The hole that the screw goes through gets spider cracks and leaks oil out. Then there is a larger o-ring between the reservoir and the pump (that seems to be the one you think may be leaking). How are you getting water in that area of your boat anyway?

 

[Sugo]

Re: Merc Trim Pump Questions

I believe I have 2 issues, The water can only be getting in to the system via the rams or leaky fittings on the ram. (Below the waterline) The leaky seal in the pump housing allows a hint of milky oil to make it's way up into the pump motor.The pump motor's output shaft is connected by a small adapter to the shaft that drives the pump impeller, it is the seal on this shaft that is leaking, not the o rings. I am going to wait until I have time to rig up something that allows me to pressure test the system, correct the issue then replace the pump.