Boomyal
Supreme Mariner
- Joined
- Aug 16, 2003
- Messages
- 12,072
Last season I noticed water in my lower drive. I drained it, refilled it and took the boat out on a crab trip (5 or so hours in the bay). When I got back I drained the drive again and got water.
I once again drained the drive and pressure tested it. The guage dropped pretty quickly. I checked all around the prop shaft and prop shaft carrier and nothing was evident. I pumped it up again and could hear it distinctly gurgling between the lower and upper gear cases.
Fast forward to May. I finally got around to pulling the drive and taking it down to my local OMC mechanic. He graciously allowed me to take the drive apart in his shop, with his expert guidance. Once I got the drive torn down, with all the possible areas of leakage exposed, a pressure test would not pinpoint the leakage but it was still happening. No bubbles, no noises.
Finally, I got a rope, tied it around the lower gearcase, pumped up the pressure tester and lowered the drive over the dock into the Mighty Columbia River. Guage continued to drop but no bubbles. Finally I pushed the shift cable under water and bubbles started to stream out.
Turns out the outer cable sheath was cracked about 8" past where the cable comes out of the shift housing. This is where the water was entering the lower gear case. All other points of possible entry proved to be sound. The remedy was going to be to use heat shrink tubing to re-cover the $500 cable. It took me about 6 hours of effort to find and retrieve 3/4"-3:1 adhesive lined shrink tubing. Many stores had the plain 3/4" but finally I found one that carried the adhesive variety.
Bottom line, it's all sealed up and back together. Now all I have to do is re-install it. That shrink tubing made a nice solid casing and it appears to be pretty tough stuff.
This was also a note to state that it is difficult to pressure test an OMC hydro or full mechanical lower unit. Even without cracks in the cable, you will have air leaking out of the drive at the end of the cable, inside the shift converter box.
I once again drained the drive and pressure tested it. The guage dropped pretty quickly. I checked all around the prop shaft and prop shaft carrier and nothing was evident. I pumped it up again and could hear it distinctly gurgling between the lower and upper gear cases.
Fast forward to May. I finally got around to pulling the drive and taking it down to my local OMC mechanic. He graciously allowed me to take the drive apart in his shop, with his expert guidance. Once I got the drive torn down, with all the possible areas of leakage exposed, a pressure test would not pinpoint the leakage but it was still happening. No bubbles, no noises.
Finally, I got a rope, tied it around the lower gearcase, pumped up the pressure tester and lowered the drive over the dock into the Mighty Columbia River. Guage continued to drop but no bubbles. Finally I pushed the shift cable under water and bubbles started to stream out.
Turns out the outer cable sheath was cracked about 8" past where the cable comes out of the shift housing. This is where the water was entering the lower gear case. All other points of possible entry proved to be sound. The remedy was going to be to use heat shrink tubing to re-cover the $500 cable. It took me about 6 hours of effort to find and retrieve 3/4"-3:1 adhesive lined shrink tubing. Many stores had the plain 3/4" but finally I found one that carried the adhesive variety.
Bottom line, it's all sealed up and back together. Now all I have to do is re-install it. That shrink tubing made a nice solid casing and it appears to be pretty tough stuff.
This was also a note to state that it is difficult to pressure test an OMC hydro or full mechanical lower unit. Even without cracks in the cable, you will have air leaking out of the drive at the end of the cable, inside the shift converter box.
