1978 evinrude 115hp power trim won't go down

[octanerocks]

I have a 1978 evinrude 115 that has been sitting for a long time. The power tilt and trim operates going up but when I press the down button, the motor moves a few inches, bogs down and starts making a whining noise. I've tried filling the reservoir, which was low, and tried bleeding the air out but now fluid is slowly leaking out around the manual release valve. There is one solinoid for the power trim, I was told that it uses power directly from the switch for going down. I have not tried going directly to the battery, I'm not sure which wires are for up and down. I have a clymer manual that should be in the mail within a couple of days but I don't know if it covers the tilt system. Any help would be appreciated.

 

[MaPaHa]

Re: 1978 evinrude 115hp power trim won't go down

If it's like my '77 140 Evinrude, there are 3 wires that run the motor. Up, down and negative. It sounds like the electrical is working ok if it tries both ways. You adjust the fluid level with it all the way up. There's a fill screw on the back of the trim cylinder where you fill it. I use an old differential fluid cap with point on it to fill it. (cap used on a quart of the right fluid. use lift fluid or Dextron III fluid). The system is self priming with 3 to 4 cycles up and down. Then re-check level. It should dribble out when full up. If not, then add.

I had a problem one time with some of the hydrolics sticking and wouldn't go one way ( I forgot which way) and a boat mechanic had to pull the motor to get to the valve, so try to fill it and work with it. Otherwise you have to pull the motor off the boat to get into the control valve. I remember something about the manual release only needing to be turned a small amount and any more messed things up. I'm pretty sure I turned it more than it needed and caused it to leak so they fixed that too.

 

[octanerocks]

Re: 1978 evinrude 115hp power trim won't go down

I believe it is the three wire system, I will try jumping the down wire to the battery directly after filling and bleeding it again, I'll try tightening the manual valve more, try to stop it from seeping, but I'm afraid I'm going to have to pull the motor if all of that don't work. Which color wire is the down wire?

 

[octanerocks]

Re: 1978 evinrude 115hp power trim won't go down

When I put the green wire to the positive, the hydraulic ran much faster than using the switch on the throttle, but someone had to be standing on the motor for it to move down. The up button quit working all together, had to manually energize the solinoid to raise the motor. I tried tightening the manual release, I still cannot get it to stop leaking, I'll probably gave to fork out another 75 bucks for the manual release valve. Could the leaking manual release valve cause the motor to not go down?

 

[RRitt]

Re: 1978 evinrude 115hp power trim won't go down

open the manual release. If engine does not fall from gravity then one of your rams or pivot axis is seizing.

 

[octanerocks]

Re: 1978 evinrude 115hp power trim won't go down

The motor does go down when the manual release is opened, now it's leaking, tried to tighten it with a wrench, won't stop leaking fluid. Can the o ring be replaced in there?

 

[RRitt]

Re: 1978 evinrude 115hp power trim won't go down

let the engine fall onto blocks to relieve pressure then tighten MRV. MRV does not need to be torqued. You can damage it or valve body by using torque. If it leaks down after firm seating then the valve body needs rebuilding. The oring on tip of mrv can be replaced but it is not easy. I turn them on a lathe to cut out old rubber cleanly without scratching aluminum. if very careful, you can do same with jewelers screwdriver. briggs and stratton carb rebuild kit should be same size oring although i'm not sure. I buy my seals in industrial bulk and have never actually tried the briggs. people say it works though.

 

[Bob_VT]

Re: 1978 evinrude 115hp power trim won't go down

The release valve is normally opened and closed using a large flat tip screwdriver. My V-4 acted a bit funny at the beginning of the season and it was low on fluid. I added fluid and opened the release valve. I had to manually lift and push the motor 5 times...... all the way up and all the way down. That will normally clear any air bubbles, checked the fuil and it was working fine again.

 

[octanerocks]

Re: 1978 evinrude 115hp power trim won't go down

I took the manual release valve out, it looked like a metal shaving on the outer o ring, put it back in and the leak is gone so that problem is fixed. I've topped the fluid off, raise and lowered the motor several times but won't go down on it's own. I have to put all of my weight on the motor and it goes down. I removed a check valve from the port side of the unit under the pump and cleaned it, engine still won't go down. I would use the manual release but I'm pretty sure it's under the water line and the motor started to scrape the ground when launching with the engine down. I don't know how well the engine would perform being trimmed all the way up either.

 

[RRitt]

Re: 1978 evinrude 115hp power trim won't go down

The engine definitely sinks on it's own when MRV is open?
AND the trim motor is definitely spinning when you press down?
AND it still doesn't work?

then you need a valve body rebuild. check ebay. you can send it off and have it rebuilt for about $90. takes a couple weeks so you may want to make do for now and send it off when fishing is over.

 

[octanerocks]

Re: 1978 evinrude 115hp power trim won't go down

Yes that's how I get it down is the mrv.. if I'm using the button, when I put my weight on the motor, u can hear the trim motor working faster as it goes down. I'll check out ebay

 

[Joe Reeves]

Re: 1978 evinrude 115hp power trim won't go down

This problem is normally caused by the two nuts (one on each side) retaining the steering tube either being too tight OR corrosion has set up in the transom brackets surrounding the tube. If so, the cure is to loosen one of the nuts a couple turns, then using a 2x4 or wood of your choosing, press it against the swivel bracket (as close to the steering tube as possible) and belt it with the biggest hammer you have to loosen the corrosive grip on the steering tube.

The engine actually goes down due to gravity, that is the oil pump is simply draining away the fluid from the tilt cylinder. After that fluid is drained away, hydraulic power is then applied to the fluid pertaining to the trim rams which will then pull the engine down.

The fact that you can make the engine go down with your weight leans to the possibility of the tight steering tube scenario.

 

[octanerocks]

Re: 1978 evinrude 115hp power trim won't go down

Ok I can try that Friday when I go to work on it, working 16 hr shifts today and tomorrow, It will go down on own weight with the manual release though. Since the hydraulic motor sounds like it's running faster when power is taken to the green wire straight from the battery, I might try also putting another switch at the rear of the boat and seeing if that works any better as well

 

[Joe Reeves]

Re: 1978 evinrude 115hp power trim won't go down

It will go down on own weight with the manual release though.

Well, that sort of kills the corroded steering tube theory, however it was worth mentioning.

 

[octanerocks]

Re: 1978 evinrude 115hp power trim won't go down

I'll try to put that switch in, and keep working with it, I might try a different battery just to rule that out, although I had mine tested when I thought it was bad earlier this year, turned out to be the starter solinoid was bad

 

[octanerocks]

Re: 1978 evinrude 115hp power trim won't go down

Fixed incase anybody else has this same problem, it was the shuttle valve behind the valve under the hydraulic motor on the port side. I pulled the trim unit off of the boat but the valve came out the front of the unit, didn't actually have to pull the unit off. I sanded it down with 220, cleaned it, put it back in, works perfectly now. Thanks for all of your help, it's nice to have a functioning power tilt and trim