Logo
FULL SITE MENU

Replacing tilt/trim motor on 80's Mercury 140

M

mmoncur

New member
Hi,

My Mercury 140 (1980 or 81) motor came with the old-style Tilt & Trim system that has 2 rams and a hydraulic pump with a square reservoir mounted in the boat, with hoses going to the rams from there.

It currently trims down but not up and I have the issue narrowed down to the motor -- everything else seems to work electrically, but when I try to apply power directly from +12V to the motor's "up" connection, bypassing the solenoid, it does nothing and heats my jumper wire up to the melting point within a second. So most likely the motor is shorted out.

There are various 3rd-party motors available from Arco, Prestolite, and API, they all include the motor and reservoir only and you attach them to your existing pump, valve body, etc.

Has anyone done this procedure? How hard is it to replace? I'd like to know what I'm getting into before I drop $100-200 on a new motor. I can also get a new entire pump assembly but that gets closer to $500.

Thanks!
 
It is not as difficult as it looks.Take plenty of photos of where everything before dismantling.Transfer the electrical parts over fill and bleed and you should be good to go.
Before you drop a couple of hundred,why not pull the pump motor and give it a good cleaning,check the brushes,might be as simple as that,or take it to an auto electrical shop and let them do it?
 
Thanks!

So far I have the 4 hydraulic hoses unbolted, tomorrow I will take lots of photos and remove the electrical connections.

(I know the hoses don't need to come off, but the whole unit is mounted in a hole in the back of the boat and I want to remove the whole unit so I can repair it properly.)

I have a motor on order, I will take a look at the old one first of course.
 
Motor and solenoid replaced, and my tilt/trim works! Thanks for the encouragement.

The old motor actually did turn both directions, but it seemed weak in the "up" direction. When I connected a battery to it it just buzzed, and when I connected the battery to the new motor's "up" circuit it practically jumped off the table from the torque.

The hardest part was dealing with the small hole in the back of the boat the whole unit was installed behind -- that made it hard to reconnect hydraulic hoses and wires. Also, it didn't work at first due to low oil, and I had to bleed the system by moving the motor up and down (manually) 4-5 times, topping off the SAE 30 oil each time. After a few of those the pump was able to raise the engine.

I will post some pictures of the process later. Time to go to the lake!
 
Back
Top