90 hp evinrude tilt/trim issues

[misery]

Hi all. My 86 90 hp evinrude has a funny problem with the tilt/trim feature. Whenever I tilt the motor up to the trailer position, the trim rams are fully extended, which I assume is normal. The problem occurs when I try to lower the motor after launching when i press the trim down button one trim ram will go down then the other, then finally the tilt ram starts to go down but when it reaches about the mid way point it basically goes into free fall. I just put this motor on this boat this summer and the wiring was disconnected from the the trim control box on the back of the motor so is it possible I fudged it up or am I just fretting about nothing?

 

[Haffiman]

Re: 90 hp evinrude tilt/trim issues

Most likely air in the system. Remove the fill screw, run the trim up and down, refill oil if needed. Try to have the boat 'bow down' to keep the trim unit vertical.

 

[misery]

Re: 90 hp evinrude tilt/trim issues

Thanks for the reply Haffiman, I did check the fluid level and it seems to be right. Would it not make more sense for the trim rams to remain in the extended position until the tilt cylinder can lower the engine down on to the trim rams?

 

[boobie]

Re: 90 hp evinrude tilt/trim issues

Sounds like you have a valve leaking in the unit itself. As long as it's working, keep on using it. Did you check the fluid level in the full up position ??

 

[Haffiman]

Re: 90 hp evinrude tilt/trim issues

How the rams move and engine moves when going down has a lot to do with balance and friction.
If the tilr ram need to pull down the engine (powerhead end heavier than gearcase end), normally the trim rams will go down before enough pressure on top of the tilt ram to start pushing down the engine. A slightly difference in friction, normally in upper rod bushing, in the trim rams, they may not be in synch. The force needed to tilt down the engine then depends on weight ballance powerhead - gearcase, and weight will shift to gearcase as engine is trimmed down. What might make it a bit more difficult is if the upper bushing for the tilt rod is beginning to seize up, which is quite normal!! In your case I believe it is a combination of several ov above mentioned, but when it comes to the free-fall part, an air bubble under the tilt piston gets compressed when the gearcase end reaches a certain downforce overpowering the friction in the upper tilt cylinder bolt.
Be sure to get all air out of the system, and remove, lubricate, change bushings for upper tilt cylinder bolt before it seizes up totally.

 

[willamettejeff]

Re: 90 hp evinrude tilt/trim issues

Normally trim rams will stay extended when tilting down and catch the motor during the last portion of travel. The motor tilts down by relieving the pressure on the tilt ram and allowing gravity alone to lower the motor. There is no hydraulic pressure applied to push the motor down. If there is excessive binding in the tilt tube as Haffiman has said then the trim rams will pull in first as yours are doing before the motor tilts down. Eventually if enough binding occurs then the motor will not go down at all without being manually assisted. The free-fall you are experiencing is simply that all of the hydraulic pressure is being removed from the tilt tube before your motor is down and there is then none to resist against the motor free-falling as happens normally, only the binding in the tilt tube.

You need to lubricate your tilt tube (where the motor hinges up and down and most-often where the steering cable goes through). You'll find 2 grease fittings in front of the tilt tube, one on each side. Adding grease may be enough or you may have to disassemble and clean if rusted.

-- Jeff