Gearcase Guru's step forward-- Stripped LU drain hole thoughts (crazy?) -- pix

[motomania]

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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[stratos284]

If it was me I would use the longer bolt before I would use the heli-coil, If you drill and tap crooked the washer would not seat good and you know what would happen then.
I would also drill the end of the new bolt deep enough to slip the magnet in there a little below the surface, then loctite the mag in there and peen the end to help it from coming out. Then you'll still have somewhat of a magnet bolt.

Also since I have a machine shop 50 feet from where I'm sitting if you want the bolt fitted with the mag, IM me for my address and you can mail the bolts here and I'll take care of the fix for ya. Phil

[noelm]

just use the bolt that fits the washer the best and forget the magnet, it is nice to be there, but if you have a gear failure, a small magnet is not going to stop/catch anything, just change the oil regularly

[motomania]

Thanks for the info guys! I went ahead and got a 3/4" stainless, allen head domed bolt (like the top one in the pic), and a socket cap allen bolt (like the one in the bottom pic). The socket cap one fit perfect, but of course, the head was not flush with the gearcase, by about an 1/8". Not a huge deal, but not very clean looking, or hydrodynamic. No dice.
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The one with the domed top, did not want to seat flush into the recessed pocket for the drain bolt; the head/shoulder was a pinch too broad. But, that's nothing my angle grinder could not take care of. Several minutes later, after grinding evenly around the head of the domed bolt, it fit flawlessly. Nice and recessed, like the factory drain bolt.
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The great thing is, that now the drain bolt is actually biting with about 7 threads, vs. the 3-4 from the factory. Nice tight seal. Now to leave it sit overnight and see what becomes of it; but I anticipate no problems.
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I would like to pressure test the lower unit, but I'm not sure how or where to get the fittings to thread into the drain/fill holes? Any thoughts?
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Dang Phil, that's a very tempting offer to have that magnet seated into the drain bolt. I may take you up on that. Although, the weather is still tolerable enough to fish around here, so I'll be using the bolt for a while.
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But, like noelm mentioned, if something lets loose; the magnet won't save me.

[gearcaseman]

Excellent idea. Should work just fine. Magnet not all that important anyway.

[motomania]

Thanks again Eddie, you're the best!
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And just out of curiosity. Where do you guys get the necessary fittings to pressure test the lower units?
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Fabricate them yourselves?

[gearcaseman]

Well, that's what I did anyway. My Dad was a machinist for 60 years, and he made me one out of brass @ 20 years ago. Has @ 1" of barbed end on it for hose retention and @ 1/8" hole in the center. Has worked great since. We "O" ringed the threaded end for sealing, much like the ring that is on a drain plug.

[motomania]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gearcaseman &raquo;</TD></TR><TR><TD CLASS="quote">Well, that's what I did anyway. My Dad was a machinist for 60 years, and he made me one out of brass @ 20 years ago. Has @ 1" of barbed end on it for hose retention and @ 1/8" hole in the center. Has worked great since. We "O" ringed the threaded end for sealing, much like the ring that is on a drain plug. </TD></TR></TABLE>
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I see, thanks Eddie. That's kinda what I was thinking it would look like.

[gearcaseman]

No problem, hope things work out for you!