Finding Leaks in a Boat

Not again…

In my last blog entry (Engine Outdrives: Inspect Those Bellows), I told you about “a friend of mine” who discovered a leak in a little runabout he had just bought. Soon after he fixed the U-joint bellows boot in the stern drive that was cracked from age and use, he took his family out.


In addition to the U-joint bellows boot, the shift cable boot (below and to the right of the gimbal bearing shown here) and the raw-water feed hose (upper left) also should be replaced about every six years. Stay tuned for a blog on corrosion in the gimbal bearing, also visible here.

When I, er, I mean, he opened the doghouse to check on things, he found that he still had a leak, somewhere. But he didn’t have a clue how it could still be leaking. He had fixed the leak by replacing the cracked rubber boot, right?

Well, turns out he had fixed one of the cracked rubber boots. As it turns out, there’s another boot that will spill water into the bilge: The shift cable that runs through the drive has a boot of its own. Although the shift cable boot is completely hidden and not susceptible to possible photo-aging, it can split and allow water in.

Water won’t get into the gimbal bearing unless it gets deep enough in the bilge to seep back in. The factory-recommended service interval for the shift cable boot also is six years. The leak is typically slower, but it’s still a leak and it had to be fixed.

While my friend was fixing the shift cable boot, he saw one last piece of rubber in the drive — the raw-water feed hose. This hose also has a six-year service interval, so he figured he would replace it while he was in there. The parts guy told him those hoses don’t break often, but the inside walls can separate and collapse, which will cause the engine to overheat. It’s rare, but after pulling the drive apart twice, he wasn’t taking any more chances, so he replaced that too.

Next trip out to the lake, he checked under the doghouse again and it was nice and dry. Looks like he finally fixed all the leaks. This time I’m sure. I mean, he’s sure.

- Brett Becker

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