This is my first time posting, though I've read through a lot of older threads in search of information that could help me troubleshoot this problem.
I have a 1979 Johnson 70 HP with a manual tilt / trim mechanism and I salvaged a power tilt and trim assembly from an early 80's Johnson 115 HP motor (not sure the exact year) with the intention of repairing and installing it on the 70 HP. The problem is that the tilt ram (the larger center hydraulic ram of three) does not come down when the unit is trimmed down. I have topped off fluid, and subsequently drained and re-filled with new fluid. All electronics appear to work fine -- I can get the motor to spin both ways. The trim rams (two smaller rams on the outside) move up and down fine, and the tilt ram does go up. In fact, the tilt ram goes up even when I'm trimming down and the other rams are going down.
I've never worked on hydraulic systems before, but from the other posts that I've read I believe this might indicate a leak somewhere in the system. I have noticed that the fluid looks frothy with tiny bubbles after trimming up and down. The only way to get the trim ram to go down is to completely remove the manual release valve and apply quite a bit of pressure on the ram. It will come down in spurts and spits out a lot of air and fluid out of the release valve. All of this testing has been on the bench... I've never had it installed on the boat with motor weight on it.
I have a low resolution exploded diagram of this assembly from a marine parts supplier website, but I'm hoping to avoid replacing every o-ring and seal in hopes of finding the leak. It looks like buying rebuild kits for the entire assembly would be costly and since the unit "mostly works" I'm thinking that the problem might be localized. Can anyone help me narrow in on what the most likely problem areas are?
I have been able to remove the shuttle valves for inspection (I had to make a special screwdriver out of flat iron because the slots were so chewed up) but I have not been able to loosen the cap on the tilt ram yet. If my problem is likely to be in the tilt ram, then I'll need to look at buying or making a tool for that.
I have a 1979 Johnson 70 HP with a manual tilt / trim mechanism and I salvaged a power tilt and trim assembly from an early 80's Johnson 115 HP motor (not sure the exact year) with the intention of repairing and installing it on the 70 HP. The problem is that the tilt ram (the larger center hydraulic ram of three) does not come down when the unit is trimmed down. I have topped off fluid, and subsequently drained and re-filled with new fluid. All electronics appear to work fine -- I can get the motor to spin both ways. The trim rams (two smaller rams on the outside) move up and down fine, and the tilt ram does go up. In fact, the tilt ram goes up even when I'm trimming down and the other rams are going down.
I've never worked on hydraulic systems before, but from the other posts that I've read I believe this might indicate a leak somewhere in the system. I have noticed that the fluid looks frothy with tiny bubbles after trimming up and down. The only way to get the trim ram to go down is to completely remove the manual release valve and apply quite a bit of pressure on the ram. It will come down in spurts and spits out a lot of air and fluid out of the release valve. All of this testing has been on the bench... I've never had it installed on the boat with motor weight on it.
I have a low resolution exploded diagram of this assembly from a marine parts supplier website, but I'm hoping to avoid replacing every o-ring and seal in hopes of finding the leak. It looks like buying rebuild kits for the entire assembly would be costly and since the unit "mostly works" I'm thinking that the problem might be localized. Can anyone help me narrow in on what the most likely problem areas are?
I have been able to remove the shuttle valves for inspection (I had to make a special screwdriver out of flat iron because the slots were so chewed up) but I have not been able to loosen the cap on the tilt ram yet. If my problem is likely to be in the tilt ram, then I'll need to look at buying or making a tool for that.
