Tilt up, no down

[Aviator19]

Mercruiser Alpha one (I think) sterndrive with 140 HP engine I/O:

I recently replaced the hydraulic pump/reservoir since the last motor stopped spinning. I guess it was as old as the boat. Engines runs great though!

Anyways, after installing the new hydraulic pump I took the hydraulic cylinders apart to replace the O-rings as there was a leak comming from the cylinders somehow. New ones costs more than the o-ring kit so I wanted to see if I could fix it myself.

I put the cylinders back together, filled the pump with fluid, connected the battery and spun the motor in up direction. Stern drive went up quickly with no problem.

Then I pushed the switch in the down position...motor spins the opposite direction but the sterndrive stayed in the up position. With some curiosity I walked over and tryed pushing the drive down by hand and with little force it moved.

A few more times spinning the pump in the down position and visiting the sterndrive I eventually got the sterndrive down.

A couple more times of that (I was thinking there might have been air in the system) and unscrewing the reservoir vent to bleed air it still dosen't want to come down on its own.

Another thing I noticed...when I got the drive all the way down I can lift it by hand all the way up. But when it's pumped all the way up it stayes up.

So I'm thinking maybee the piston inside those hydraulic cylinders where moving, but the push rods where not retracting along with the pistons???

Did I put them back together incorrectly?

Thanks.

 

[Don S]

Re: Tilt up, no down

Did I put them back together incorrectly?

Since I can't see inside it from here, I really can't say if you did or not.

The piston is supposed to be attached to the piston rod, was it? You had it apart?

Are you sure you aren't out of oil in the pump?

Does the motor run when you try to put it down

 

[Aviator19]

Re: Tilt up, no down

When taking it apart, I unscrewed the end with a pipe wrench, then pulled out that push rod which extends/retracts inside a cylinder tube (Which also came in that O-ring kit to replace the old one).

After pulling out the rod from the cylinder tube there was a solid cylinder block screwed on the end of that push rod. And still inside that tube there was a piston (I'm calling it a piston). So I guess that rod rests against the piston which I think causes the rod to extend when the pressure moved the piston out.

I put it back together the same way I took it apart after putting new o-rings on the parts.

I was thinking, was I supposed to put some fluid in the cylinder tube before putting the rod back in somehow?

 

[wcsparky05]

Re: Tilt up, no down

yeah, great engine. got the same on my invader. so, where is hemet, ca?

 

[Aviator19]

Re: Tilt up, no down

The engine seems to be running great. Just can't aim the prop to actually use it lol.

Hemet is in southern California on the west side of the mountain from Palm Springs.

 

[Aviator19]

Re: Tilt up, no down

Tryed messing with the boat again.

First thing I did was to unbolt the hydraulic cylindars from the stern drive to see how the two operate individually with the hydraulic pump running and discovered they do both extend together but when pumping to the down position one cylinder keeps extending, but the other does retract.

So right side extends in both pump directions and the left extends and retracts. Any new ideas to my failure?

I also disconnected the hoses from the cylindars to see what happens when I pushed/pulled the piston rods by hand and noticed the fluid squirting out of both holes in the right cylindar (the one appearing to be working correctly). On that left cylinder, fluid squerted out of one hole in both piston rod directions and none out of the other hole.

Again I'll try taking it apart again tomorrow after checking back here.