My 86 Evinrude 150 (model # E150STLCDC) has the drain hole in the lower unit stripped out. I'm religious about using a torque wrench on every bolt, including the lower unit drain bolt; as I have the factory service manual. I guess after 20+ years and possible over tightening before; the threads gave up the ghost. (I truly don't feel like I'm to blame on this one.................or maybe I'm kidding myself )
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I've got a helicoil kit, with the proper size and was ready to start drilling. But, looking at the drain plug, and inside the drain hole, got me thinking. As I'm concerned with getting a perfectly perpendicular hole, for a proper seat with the helicoil kit.
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Only the outer 1/4" of the drain hole threads are stripped out. As the drain plug only has approximately 1/4" of threads. The drain plug hole still has about a half inch of solid threads left, but they're a bit deeper in the case. I ran a similar sized bolt in the gearcase to confirm, plenty of threads in there; and plenty of bite.
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This may seem a bit unorthodox, but what would be the harm, buying a stainless 3/4" long, allen head bolt, with the top of the head rounded (like the one on top in the picutre), so it would sit below the plane of the gearcase outer surface. This would give the bolt a 1/2" of threads to still bite into. And if the factory gasket on the drain bolt fits, what would the harm be?
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Yes I would lose the magnet, but that's not a huge deal. And our ACE hardware has a fantastic, bulk fastener selection; with loads of stainless pieces.
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I'm just thinking out loud here, and would feel better NOT having to drill into my gearcase if could be avoided.
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Any thoughts are greatly appreciated.
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