1978 115 johnson tilt n trim

wavrider

Chief Petty Officer
Joined
Nov 26, 2007
Messages
543
It will go up, but it wont go down

Worked fine three months ago. Was stored in vertical position.

Went to start the engine today. Tilted it up and it would not go down.

Could not get the release screw to open so disconnected the hydraulic line on bottom of unit to allow fluid to drain and motor slowly came back to vertical position.

Refilled reservior, tried again, it will go up but not go down.

Motor is running in both directions, can hear motor strain in trying to get unit to go down but it only moves about a half inch then stops.

Manual says trim check valve plugged: pump control piston failing to open check valve or several other parts.

Any suggestions on what I should check first, order of sequence?
 

walleyehed

Admiral
Joined
Jun 29, 2003
Messages
6,767
Re: 1978 115 johnson tilt n trim

Does the electric motor spin when you hit down? If it doesn't, it's a trim relay in the black box usually mounted under the splashwell about 6"X8".
 

wavrider

Chief Petty Officer
Joined
Nov 26, 2007
Messages
543
Re: 1978 115 johnson tilt n trim

I hear the motor spin prettty good rpm then it is like it just hits pressure and goes under a load trying to tilt down.

Motor wil move downward maybe a half inch and then just stop any movement at all.
 

wavrider

Chief Petty Officer
Joined
Nov 26, 2007
Messages
543
Re: 1978 115 johnson tilt n trim

Update

I lowered engine, drained the fluid. Shot a can of Pb blaster into the reservoir.


Tilted it up, had a helper try to tilt down and was able with the assistance of me pushing on it to get it to go down to the trim rods. cycled this way three times then left it on the trim bars, called it a night.

Had to make a run to the airport so got home late tonight, went to the boat, threw the battery switch to on and it tilted up fine, then tilted down and even pushed the trim bars all the way in.

PB blaster got the valve unstuck and seems to be working fine.

I will let it soak another day and then cycle it a few more times, fill it with atf and cycle it, drain it so I get all the residue out of the pb blaster and fill it up. See what happens.

I do not know if this is a "FIX" but it worked, I figured had nothing to loose with the TNT being stuck so I tried it.
 

powertrim 1

Recruit
Joined
May 11, 2010
Messages
1
Re: 1978 115 johnson tilt n trim

not a reply ineed a anwser. im new to this so any help will anwser my problems. i have a 1976 135hp johnson outboard. when the boat is on plain the trim unit will not raise the motor. it will go down but not up. please help me if possible. thanks for all of everybodys time and efforts.
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: 1978 115 johnson tilt n trim

Check the trim switch when in the up position. Also, the trim solenoid is energized when the switch is in the up position. That solenoid could be bad.
 

hippchip

Recruit
Joined
Feb 18, 2010
Messages
5
Re: 1978 115 johnson tilt n trim

Sounds like I have the same problem. Where is the check valve that you sprayed the pb blaster? I love that stuff.
 

hippchip

Recruit
Joined
Feb 18, 2010
Messages
5
Re: 1978 115 johnson tilt n trim

I got the release screw off. Is the fluid supposed to come out? Is the release screw on the pump on the right and the motor is on the left correct. release screw is midway on the pump?
 

matt lewis

Recruit
Joined
Aug 11, 2011
Messages
4
Re: 1978 115 johnson tilt n trim

is there anyone who knows the workings of a 1978 115 johnson tilt/trim system?
 

matt lewis

Recruit
Joined
Aug 11, 2011
Messages
4
Re: 1978 115 johnson tilt n trim

Ihave messed with it for a while now and can't figure it out.
The pump is working and the trim rods move but the piston shaft doesn't. I have drained it, filled it, extended the trim rods, filled the resevoir, worked it manually up and down even while running the pump, and nothing. I noticed that when running it down, pressure builds up and pushes the trim rod out when I shut off the pump.
 
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