1978 Johnson 175 trim and tilt

[hippchip]

My trim and tilt only goes up. When trying to go down it makes the sound like its going to work but doesnt go down. It is so far up that I can not take the motor cover off to get to the relays. Can I get it to go down manually? Does anyone know where I can get a diagram of the trim and tilt? Any other ideas?

 

[emdsapmgr]

Re: 1978 Johnson 175 trim and tilt

Not sure why you want to take the cowling off. That 1978 model had a separate power trim relay box which mounted under the rear splashwell of the boat. Yours should have a trim solenoid for the up movement only. The down is wired direct through the switch on the control box handle. The later models had the trim box under the cowling. The original factory service manual has a color coded wiring diagram in the back. You can get an original from Ken Cook Co., in Milwaukee, or from: outboard books.com on the web. If you look at the side of the starboard transom bracket, you will see a large screw head that is recessed in the bracket. That is a pressure relief valve for the trim system. If you slightly unscrew it (it is not meant to be removed) the pressure in the system will bleed internally and you should be able to move the trim unit without any electricity.

 

[hippchip]

Re: 1978 Johnson 175 trim and tilt

Ok, I was able to lower the outboard by internally bleeding off the pressure. I found the electrical box and switched the relays. It still does the same thing. It sounds like power is getting to the pump but it doesn't move. It sounds like the relief valve is relieving. I am not sure what the two silver bars that the motor rests on when it is completely lowered, but they look fully extended(almost 3 inches). Even when I lower the unit manually. It comes to a rest on the silver rods. I was looking at a picture of the trim and tilt on the web and the rods looked shorter.

 

[emdsapmgr]

Re: 1978 Johnson 175 trim and tilt

You can further test the trim motor by temporarily connecting it direct to the battery. You can further lower the engine on those two trim rams when the pressure relief valve is open. You may have to put some muscle into it, but you should be able to get them to retract, albeit very slowly.

 

[hippchip]

Re: 1978 Johnson 175 trim and tilt

If the relief valve is stuck closed would that prevent downward movement? Also, everything that I have seen shows a solenoid for up only. In the box I do not see a solenoid. I have two relays. I swapped them with no change.

 

[emdsapmgr]

Re: 1978 Johnson 175 trim and tilt

Sure your engine is a 78? The 1978 models had a single relay for the up movement. These early trim motors were a 3-wire motor. In midyear 1981, OMC changed to a pair of interchangeable relays and began using a 2-wire motor.. Maybe someone changed your trim system over.

 

[RRitt]

Re: 1978 Johnson 175 trim and tilt

look to see if trim rams are retracting and only tilt ram is stuck.
if whole thing is stuck then it is a pump issue.
if trim rams are moving then it could be either pump or tilt ram.