1979 mercury 900 90hp 2 stroke trim problem

[smokeyblaze]

I'm finally getting everything back together and now I've gotten to the tilt /trim. It makes noises when trying to trim up and down but the motor is not moving at all. I looked at the trim reservoir where the hydraulic lines run to and I can't seem to find where to add the oil , there is knob that says unscrew to engage and screw in to disengage and I tried removing it with no luck. It recommends 5w-30 synthetic oil and I was thinking maybe it just needs oil in it before it will trim up and down but now here I am stuck looking like a jackass when I don't know where to add the oil. The motor has been off of the boat for about 8 months so maybe all the hydraulic fluid drained out? How would I go about adding that also. Please help me

 

[Laddies]

Re: 1979 mercury 900 90hp 2 stroke trim problem

Over the years Mercury has recommended any oil that is liquid just about we use dextron in them all

 

[smokeyblaze]

Re: 1979 mercury 900 90hp 2 stroke trim problem

That tells me alot that I didn't know but I still do not understand Where to add the oil. Thanks for your patience.

 

[Laddies]

Re: 1979 mercury 900 90hp 2 stroke trim problem

In F and it's full then level with the top of the hole

 

[smokeyblaze]

Re: 1979 mercury 900 90hp 2 stroke trim problem

thanks man. you guys here never fail. I owe everything to this forum. I'm just about ready to get on the water. Thanks bud

 

[smokeyblaze]

Re: 1979 mercury 900 90hp 2 stroke trim problem

so where do i add the hydraulic fluid?

 

[Laddies]

Re: 1979 mercury 900 90hp 2 stroke trim problem

With a squirt can or a pump at the fill hole, the same hole that you check the level with item F.

 

[smokeyblaze]

Re: 1979 mercury 900 90hp 2 stroke trim problem

I put 5w30 motor oil in item F

 

[Laddies]

Re: 1979 mercury 900 90hp 2 stroke trim problem

That's fine the 5W30 is your hydraulic oil.

 

[smokeyblaze]

Re: 1979 mercury 900 90hp 2 stroke trim problem

I'm having a problem with it now cutting in and out ,It's just making noise and the motors not moving only solenoids clicking.I took it out on the water and it stopped working about 10 minutes later it was working off and on a couple more times but more off than on until i gave up and decided to troll back to the ramp . I'm thinking that its just a bad connection somewhere. I picked it up and hook it a few times and it started working for a minute or so I also found a loose ground that was just hanging around not even going to anything I know it was previously hooked up before i pulled the motor off about 8 months ago , I'm sure it goes somewhere on the trim reservoir but not sure where. Would a kink in the hydraulic lines cause this? Does anyone know where all the grounding points are?

 

[Chris1956]

Re: 1979 mercury 900 90hp 2 stroke trim problem

That motor has three connections. Black is ground for both up and down. Blue is up, Green is down and one of them receives +12V to operate motor, in that direction. You should have one solenoid.

The motor has a bimetal overheat breaker inside of the casing. Sometimes a bit of rust messes them up.

Bypass the solenoid to test up circuit. BTW - the three prong PTT control socket looks corroded. You might clean it up or risk a bad connection.

 

[smokeyblaze]

Re: 1979 mercury 900 90hp 2 stroke trim problem

- the three prong PTT control socket looks corroded. You might clean it up or risk a bad connection.

What plugs in that socket?? Nothings ever been plgged in there to my knowledge. Could a kink in the lines cause this?

 

[Chris1956]

Re: 1979 mercury 900 90hp 2 stroke trim problem

That three pronged socket accepts three wires, that run to the three PTT control buttons and teh trim limit switch. The horizontal slot is +12V, and the other two slots are to power the pump either up (blue) or down (green).

 

[smokeyblaze]

Re: 1979 mercury 900 90hp 2 stroke trim problem

what is the purple wire coming from the main harness?

 

[Chris1956]

Re: 1979 mercury 900 90hp 2 stroke trim problem

I believe the purple wire goes to the trim limit switch.

 

[Laddies]

Re: 1979 mercury 900 90hp 2 stroke trim problem

 

[smokeyblaze]

Re: 1979 mercury 900 90hp 2 stroke trim problem

If the solenoid is bad would it make a clicking noise?

 

[Laddies]

Re: 1979 mercury 900 90hp 2 stroke trim problem

Thats very possible

 

[smokeyblaze]

Re: 1979 mercury 900 90hp 2 stroke trim problem

I tightened a few loose connections up and it started working fine , I thought everything was fixed , then it started clicking again , I noticed if I just grab the solenoid and shake the pump a little bit It will start working again then stop in a couple minutes. Any ideas what this could be?

 

[Chris1956]

Re: 1979 mercury 900 90hp 2 stroke trim problem

Could be a bad solenoid or dirt or rust in the motor. You can bypass the solenoid for testing purposes. This will tell you if the solenoid is bad. You must use the solenoid when operating the motor, or you will burn up the wiring harness.