Mercury trim pump expert wanted

asm_

Petty Officer 1st Class
Joined
Apr 11, 2010
Messages
245
I finally got the time to work on the project boat that I have been keeping on the side of my house. The boat has few problems, but since I?m more of less using it to teach myself on how to work on boat, I don?t mind it as long as it doesn?t cost me too much extra money. This boat is a 1982 Runabout with Mercury inline 6 outboard.

The first problem I decided to tackle is the trim and tilt system. Both up and down trim/tilt function correctly with trim motor whining away in both modes and outdrive moving up and down as expected. Although I?m not entirely sure if the down motion is simply due to the gravity or if the down circuit is actually working. The major problem in the trim/tilt system is the outdrive would not stay down if the motor is shift into reverse. Needless to say, this poses a bit of problem when it comes to close quarter maneuver. Oh, yes, in case if you are wondering, I did turn the reverse lock knob all the way left. :)

Today, I decided to remove the trim pump/motor unit and get a good look at the unit on the work bench. While testing the pump/motor unit, I noticed if I energized the blue wire to the pump motor, two steady streams of fluid would pump out of the two ports mean for the up trim hydraulic hoses. Naturally, I assume if I energized the green wire, fluid would come out of the two ports mean for the down trim hydraulic hoses. To my surprise, oil did not come out of the down trim ports. It did spit a few drop but, nothing else comes out with motor running faster and faster. It?s as if motor is not loaded due lack of hydraulic fluid. I did confirm there are more fluid in the reservoir.

After hours searching on Google and iBoats, I found a few pictures of disassembled pump pictures. Based on what I observed in the pictures, it would appears the up trim takes fluid from the reservoir while down trim may(?) take fluid from the return fluid in the up trim hose. After all, there is only one intake screen.

I could be completely wrong. So, any one here that may have experience working those legacy mercury parts, I would appreciate your input . Just to recap, if the green wire is energized, should the fluid come out of the down trim ports on the control valve body?

Attached are a picture of my pump and a picture of the pump body from another picture I found on iBoats.

Thanks
 

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aussieflash

Lieutenant Junior Grade
Joined
Feb 5, 2011
Messages
1,004
Sounds like you could have air in the system.Or bad seals.If there are no leaks I would try bleeding system.No expert with outdrives though most mercury systems are self bleeeding.
In full up position,check fluid and fill then up down 3 or 4 times and repeat till it takes no more.Mine is an outboard so possibly different procedure.A mercury manual for your model would be needed for stripping down pump etc.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Yes, PTT fluid should come out of the "down" ports when the PTT motor operates. The trim pump is self-bleeding, but the cylinders need to be bled.

I have no idea why you do not get PTT fluid out of the pump, when running the motor in the down direction. Are you checking it downstream of the control valve? Is the control valve good? Remember, the control valve needs to hold the motor against full forward and reverse thrust, but still trim up, if you hit something.
 
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