Merc 50 HP Year ID then power trim question

[4barrel]

My buddy picked up a boat with a 50 hp merc. 3 cyl. with power trim.
The motor runs good, but the trim don't work.
The only Info on this motor he could find was the serial # 7070024
Once I know "what" I'm working on I will be able to get a book and understand this motor better.

I looked at his power trim stuff and wiring, He has a 3, switch panel on dash that has a, UP button a center button that says up and out, and a bottom button that is down.

If he piushes the bottom button the pump/res. make a noise,
If he pushes the up or the up/out alone nothing but if both are pressed then the pump again makes noise. But the motor don't even twitch.
He said the tank had fluid in it but said it was red...? The label on pump assembly says 5w 30 that is just engine oil right?
There are 2 wires running to the top of on lift cyl. I am guessing this is a limit switch? If so can we test it for continuity?
There are 2 small lines and 2 larger lines coming from pump, to what appears to be a dist. block, splits 1 big & 1 small to each lift cyl.
Do these systems need to have air bled from lines?
There are allen head "plugs" on the lift cyl. and one has a flat head just behind the allen on the top.
Or could it just be the wrong fluid.
Is that normal operation of the switch? ( to have to press 2 buttons to make go up)?
He also wants to add a trim gauge but not sure if this motor has/can have a sender.

 

[achris]

Re: Merc 50 HP Year ID then power trim question

My buddy picked up a boat with a 50 hp merc. 3 cyl. with power trim.
The motor runs good, but the trim don't work.
The only Info on this motor he could find was the serial # 7070024
Once I know "what" I'm working on I will be able to get a book and understand this motor better.

Huston, we have a problem.... That serial number is a 1975 number, but the only 3 cylinder engine in that year was a 65hp. The 50hp was a 4 cylinder...

I looked at his power trim stuff and wiring, He has a 3, switch panel on dash that has a, UP button a center button that says up and out, and a bottom button that is down.

If he piushes the bottom button the pump/res. make a noise,
If he pushes the up or the up/out alone nothing but if both are pressed then the pump again makes noise. But the motor don't even twitch.

The operation he's using is correct if the limit switch is faulty.

He said the tank had fluid in it but said it was red...? The label on pump assembly says 5w 30 that is just engine oil right?

Right, but a lot of people put ATF in them. it doesn't hurt to use either.

There are 2 wires running to the top of on lift cyl. I am guessing this is a limit switch? If so can we test it for continuity?

Yes, and yes... As you had to use both 'UP' buttons earlier, I'm guessing that you'll find it open circuit (common failure and most people just disconnect it and put a shorting wire in, that way it will work by just pressing the top 'UP' button).

There are 2 small lines and 2 larger lines coming from pump, to what appears to be a dist. block, splits 1 big & 1 small to each lift cyl.
Do these systems need to have air bled from lines?

Yes.

There are allen head "plugs" on the lift cyl. and one has a flat head just behind the allen on the top.

As long as the pump is filled with fluid (to the bottom of the threads of the fill plug, and the vent screw on the pump is open, the system should be self purging. If you do need to bleed air off them just loosen the flat blade screw, and do only one side at a time.

Or could it just be the wrong fluid.
Is that normal operation of the switch? ( to have to press 2 buttons to make go up)?
He also wants to add a trim gauge but not sure if this motor has/can have a sender.

Trim gauge not possible... No place for a sender... Why not just have him turn his head to see where the engine's trimmed at?

Hope this helps you a little,

Chris...........

 

[4barrel]

Re: Merc 50 HP Year ID then power trim question

Thanks AChris I will double check cyl. # so then if it is a 50hp 4 cyl it is a 1975?
Can we disconnect the lines or one line to see if fluid is flowing to the rams?
When he lifts motor manually it drops back down unless he lock it in.

Trim gauge not possible... No place for a sender... Why not just have him turn his head to see where the engine's trimmed at?

Thats what I said... LOL Told him its only a 14' you will learn seat of the pants real quick.

 

[4barrel]

Re: Merc 50 HP Year ID then power trim question

Ok plot thickens.
Yes it is a 4 cyl. 50hp so that must be a 1975 motor, will look for book on monday.


No we did the bypass and just like you said, now only have to press the middle button up & out, to make pump work but the up button has no function. Down still makes noise.

So had my buddy lift motor by hand while using trim switch, it got to a point where the motor would lift and lower with the power trim..
But when we stop using up button the motor slowly drops back dow to a point that the pump won't lift it, also when we had it lifting doesn't seem to lift all the way up to be able to lock in up positon.
My educated guess is the lift cyl.s are worn or leaking internally, There doesn't appear to be any leaking, and the tank is full, (with Trans fluid I'm guessing)
Now we aren't sure about the control knob on pump but, appears to simply be a valve to slow the motor from lifting out of water in reverse, with it turned one way we lift motor by hand no prob, all the other way, and seems to create a reverse pressure, making it tougher to lift motor by hand.
If it is the clys. are they rebuildable or are replacemants available? Are they big money?
We are probaly going to try on water for first time since he bought it, tommorow.
Any help to get the power trim working again, is a big step.