I have a 1975 MERCRUISER 120 hp with an alpha drive. I have the MC-1 style trim cylinders with the full screw on cap.
It used to drift down all the time, so last winter I had strapped it in the up position for storage. Bad choice! It now does not drift down, nor does it trim down. When I trim it in, the cylinders only collapse 3”. I tried standing on it for weight, but that didn’t move it any more. Trimming up works great.
I disconnected the cylinders from the lower unit, and was able to move the lower unit up and down no problem. So that wasn’t stuck.
I then tried to push in the trim cylinders. The left side pushed all the way in no problem. But when I pushed it in, the right side extended out. I assume it should do that? I then tried the right side, and it also pushed all the way down, but about an inch less then the other side would. But both cylinders seemed to move freely enough.
I then took the lines off the right side cylinder, and collapsed both cylinders. I removed the right cylinder and took the inside shaft out from the cylinder, and swapped it with a good used shaft assembly. Just to see if it would work. I reinstalled it, filled the pump. Then trimmed it all the way up. It then just did the same when I went to trim it in, it only moved 3” or so down.
Not sure what to check next. Is it the cylinder or the pump? I feel the cylinders work good, unless, the transfer of fluid from the one to the other when I pushed one in was not normal, then they would be questionable.
Could it be a stuck check ball in the valve not letting the fluid back to the tank?
Should I remove a line and see if fluid is coming out when I push on the trim in button?
It used to drift down all the time, so last winter I had strapped it in the up position for storage. Bad choice! It now does not drift down, nor does it trim down. When I trim it in, the cylinders only collapse 3”. I tried standing on it for weight, but that didn’t move it any more. Trimming up works great.
I disconnected the cylinders from the lower unit, and was able to move the lower unit up and down no problem. So that wasn’t stuck.
I then tried to push in the trim cylinders. The left side pushed all the way in no problem. But when I pushed it in, the right side extended out. I assume it should do that? I then tried the right side, and it also pushed all the way down, but about an inch less then the other side would. But both cylinders seemed to move freely enough.
I then took the lines off the right side cylinder, and collapsed both cylinders. I removed the right cylinder and took the inside shaft out from the cylinder, and swapped it with a good used shaft assembly. Just to see if it would work. I reinstalled it, filled the pump. Then trimmed it all the way up. It then just did the same when I went to trim it in, it only moved 3” or so down.
Not sure what to check next. Is it the cylinder or the pump? I feel the cylinders work good, unless, the transfer of fluid from the one to the other when I pushed one in was not normal, then they would be questionable.
Could it be a stuck check ball in the valve not letting the fluid back to the tank?
Should I remove a line and see if fluid is coming out when I push on the trim in button?
