Mystery Drip

[Groovitz]

Painted the lower portion of my drives this past weekend. The boat is on a lift so the tide does affect my work schedule. As I was still working on another section of the boat, the tide started to come up so I raised my drives to buy me some time before I had to raise the entire lift. A few minutes later I noticed a drip of gear lube running down the skeg from the rear of the lower gear case just forward of the prop. I realize its a seal issue, but the boat had not moved for a week. I never saw a drip of lube coming off my drive before I tilted the drives UP. Note that in the full down or IN position the drive is actually below horizontal, prop shaft pointing down astern. My drive reservoirs are full & clear. The mystery to me is 1) why would tilting the drive UP cause the lube to start dripping. Counter intuitive to me. 2) no discolor or loss of my gear lube for that drive. Thoughts? Diagnosis?

PS: I plan to drain a little lube out of that drive as soon as I can get back out under there to examine its make up.

 

[toofast]

When is the last time you changed gear oil - is my first question.

Not sure WHY you are leaking....if oil came out, water might be in. Have no idea why tilting up would make it leak, other than it was already leaking and the tilt up caused gravity to takes its cause on the oil.

The drain screw has a seal that might be leaking a bit so for sure I would drain all the gear oil, replace and then replace the tiny seals...they are $1 each.

 

[Groovitz]

The ‘Mystery’ solved. Upon draining a bit of lube from the drive, there definitely was some water intrusion. The drive was removed and pressure tested on a bench rig. 15 psi for 24 hours. NO loss of pressure, no drip. The drive was then pressurized again and tilted to duplicate the angle of trimming UP. Pressure dropped & the drip appeared. The prop shaft was removed and indicated a ‘score’ under the oil seal. Sand, and a long gone fishing line were blamed. This condition took it’s toll over time, and I have no idea how long it may have been dripping in the trimmed up position. The oem spec for shaft play was just enough to allow the shaft to slide forward in the carrier and loose the seal. I opted for a brand new lower, instead of a rebuild. Also had the other drive bench tested in the same manner. No issues.