1979 Johnson 85TL79R tilt/trim problem

[chadbrew]

Hi,
I've been working on my late father's old boat and have run into a snag. The tilt goes up just fine. Sounds good. When I try to tilt down the motor sounds good for about one second and the motor moves down a tiny bit. Then the motor sounds like it's bogging down and no movement. The manual release lets the motor down onto the trim pistons (which stay out all the time now). I can cycle the engine up and down (power up/manual down) all day. Fluid was low and I have leveled and topped off multiple times when cycling up and down to try and make sure it is full.

I have a bypass with new switch to tilt up and down wired directly to battery so shouldn't be a problem getting juice to the motor. Fluid comes out a bit frothy but not horrible. It has cleared up considerably while trying to bleed out any air. Went through a whole bottle of fluid flushing it. I'm not sure if manual release is suppose to let trim Pistons release or just the tilt piston?? I can't get trim Pistons to move at all. Im hoping I don't have to rebuild this system. It use to work, though the motor sounded weird, about two years ago but haven't had boat in the water in about 4 years. Any thoughts please?

 

[emdsapmgr]

On that 79 system, there is supposed to be a trim control box mounted under the back deck of the boat. A single trim solenoid is in line with the "up" switch. Up power comes from that solenoid's battery current. The down power goes through the trim switch on the control handle only. In this case the trim switch bears all the "down" current. Could be a defective switch. If you wire your new bypass switch direct to the motor, it won't be long before the switch will burn out in the "up" position, as it is probably not designed for that current load. The trim pistons will retract when the tilt cylinder pulls the engine down on top of them.

 

[chadbrew]

Looks like I misspoke on the battery thing. Made an assumption. My dad had tied into the wires going to the control, thus adding a switch in parallel with that control switch so one could operate the tilt from the back of the boat. It has been that way for as long as I remember. It very well may go to a relay under the deck somewhere.
So, the tilt piston has to pull the engine down onto the trim Pistons in order for them to retract? Should they also retract when manually letting the engine down rather than staying firmly extended?

 

[chadbrew]

Should the trim pistons also retract when you manually let the engine down?

 

[chadbrew]

Anyone?

 

[interalian]

Have you tried leaving the manual release valve open then powering the motor? Might push the trim rams back?

 

[chadbrew]

Yeah. I tried. The trim switch starts getting hot if I let it run for more than a few seconds. The motor starts making different noises if I let it run a bit but nothing moves. When I first hit the button, the tilt cylinder moves just a small bit then motor bogs down and no movement. Pretty confident that trim cylinders are the issue but have never worked on this stuff before so not sure where to start. Tried tapping on them while power down and all it does is change motor sound.

 

[interalian]

I didn't mean when running the power on the trim/tilt motor, more about what you would do in a situation where the electrical parts failed. I was thinking that if the manual release valve was open and the engine down as low as it would go, sitting on the rams, that when you applied throttle the rams would be pushed in by engine thrust.

 

[chadbrew]

Ah. I haven't left the manual screw open while it was in the water for fear of getting water in the system (not to mention the screw could work itself the rest of the way out and I'd lose it). But I can say that I've stood on the back of the motor to try and give it more force to push the rams in when the manual release is loose. The rams are stuck pretty good. I even tried tapping them pretty good with a hammer while the engine is going down. Nothing.

I just don't know enough about the mechanics of that system to know if it is internal pressure holding them (like a stuck valve) or the shaft itself being seized up.

 

[chadbrew]

Problem solved. Works like new now.

I took out the trim screw valve (check valve I think it is called), then took out the spring and a plastic piece inside the unit. The I used a punch and hammer to "unstick" the check valve up inside the hole. If you ever have to do that be careful as there is pressure on the back side of that check valve. Wear glasses.

To answer my own initial question - No, the trim rods do not retract when you loosen the manual release valve in normal operation.