PS:

Tell me more about how you disconnected the trim cylinder, then the unit went down…  Did you unscrew the cylinder piston from the bracket on the swivel housing, then try it?  Or, did you remove the oil line from the trim cylinder?  Am guessing you disconnected the piston from the engine, but just making sure.

OK, I hear ya.   But, it would appear that the trim cylinder is all the way down now…  How did you get it down?  It is possible that the unit is just low on hydraulic lube…  Any signs of leaking fluid on the ground??

It’s just like you say!  That trim cylinder is only working for a limited range (the trim range), then the tilt cylinder is doing all the work the rest of the way up, the trim piston is “just along for the ride” at this point.  Same thing on the way down.  You can actually hear the tone change in the system when the tilt cylinder takes over, and tilt speed will increase.  Same theory applies on the way down, the unit will tilt down relatively quickly until the trim piston hits the top of the fluid, you will hear the tone change and tilt speed will decrease down throughout the trim range.  The downward pressure created by the tilt cylinder forces the fluid out of the bottom of the trim cylinder, which is why there is only one fluid line connected to the bottom of the trim cylinder.

OK, but now I am confused again.  You say the unit will not tilt down with the trim cylinder connected to the engine.  If the trim cylinder is to blame for this condition, the trim cylinder piston would probably be stuck all the way up, jammed.  I know it is tough, because that bracket is in the way, but can you pull the trim cylinder rod up by hand??  If so, sure doesn’t seem like it is jammed.  Usually, these trim cylinders get rusted up internally and can’t be moved at all if damaged.  So, if the trim cylinder is OK, what is the issue?  Have you checked the fluid level in the unit?  There is a large screw on the side of the pump that can be removed to check fluid level, but the unit must be tilted up completely to check fluid level.  Use dexronII tranny fluid, squirt it into that hole until overflowing (with unit tilted all the way up).   Any evidence of an external fluid leak??  The only issue that might be causing a problem is the manual tilt lock mechanism.  If not properly disabled, perhaps the the tilt lock is engaging when you tilt the unit up all the way preventing it from coming down.  Check to make sure the manual tilt lock lever in in the down position.   There is a manual release valve on the pump as well, perhaps it is not tightened all the way, this is usually located at the bottom of the pump, a screw head with a large slot.  The engine has been used in salt water so it is probably jammed, don’t force it if it won’t move.

The only other issue I can think of is that the internal shock pistons/cylinders are rusted/jammed/rusted bushings/tight tilt tube, that is binding the engine making it harder for the hydaulic unit to work.  These shock absorber cylinders/pistons (2) are hidden on the back side of the swivel housing and can only be seen from underneath when the engine is tilted up.

Finally, you are correct again, that solenoid is not a reversing solenoid indeed.  That solenoid is only used in the “UP” mode, probably because much more current/effort is needed to tilt the engine up/under power, then tilting it down.  Current for tilting down is routed all the way up the the trim/tilt switch then back to the green tilt motor lead.   The tilt/trim motor has three leads, blue/green/black.  With the black lead grounded and the blue lead connected to battery positive, the tilt motor turns in one direction tilting the engine up.  With the black lead grounded, and the green lead connected to positive, the tilt motor turns in the opposite direction bring the engine down.

Perhaps you can make a video of the tilt system misbehaving, let me know if it won’t post here, you can email me with it or put it on youtube.

I guess I should have lead with safety warnings…  PLEASE be very careful messing around with the hydraulic unit, it would be very easy to get your fingers pinched in something while working on it, especially if the engine inadvertently tilts down on its own..  Safety first!  Don

Well, that is a great old engine for sure, one of the best/most reliable/rugged/simple engines ever.   Take reasonable care of it and it will provide many more years of faithful service, you just need to find an older technician/shop that is familiar with these engines.  The power trim unit is kind of funky, especially when used in salt water, the biggest  problem now if finding parts for it.

Try to post the video here.  If it is too large to post, perhaps post a link here from youtube or some other site where it will fit.  Don