Evinrude lower unit bearing housing retaining bolt stuck

The lower unit oil on my 1970 60 HP was showing water so I replaced the drain & vent screw gaskets as well as the water pump & seals since the impeller was original.....and added a "pisser".
To complete the job I ordered the shaft seals, bearing housing O ring and retaining bolt O rings. While disassembling 3 of the hex bolts came out but the head on the last bolt stripped (rounded corners). I tried a metric Allen wrench but it was too big and I did not have a grinder available. Next I tried drilling the head off but have only managed to dull the $18 hardened bit I purchased. I've resharpened and tempered it several times but the hex head remains. With hinsight I should have tried grinding the bigger Allen wrench instead of drilling. I also tried a Dremel grinding wheel which promptly sacrificed itself.
Any thoughts from the experts ? I know there comes a time to "let go" but that would be painful since I overhauled the top end last year.

Thanks,
Bumpa 53

Re: Evinrude lower unit bearing housing retaining bolt stuck

It sound like you're speaking of the top driveshaft Bearing/Seal/Housing assembly that is located directly under the water pump assy and is attached to the lower unit with four (4) 7/16" hex head bolts. However, I am at a complete loss to understand how a allen wrench could possibly be used to loosen or tighten any of those bolts.

In the future, if a hex head bolt rounds off, beat it with a hammer and punch so that it is necessary to pound/force a socket back on it, then heat the aluminum surrounding the threaded shaft to help loosen it.

For now.... use the propane torch to heat that aluminum, then use a chisel to tap the side of whatever remains of the hex head in a counter clockwise direction.

Last resort.... take it to a machine shop.

Re: Evinrude lower unit bearing housing retaining bolt stuck

If possible, I like to use a little 18V impact driver (not impact wrench) for removing stubborn bolts...going Forward/Reverse until it budges...use with heat and penetrating oil. Start with a 1/4" adapter (minimal amount of torque). Increasing the socket adapter size increases torque however also increases the possibility of shearing the bolt head.

If it breaks, I've had alot of success with left-hand bits...well centered and drilling very slow + liberal application of cutting fluid.

Re: Evinrude lower unit bearing housing retaining bolt stuck

Guys,

Thanks for quick response.
My apologies for non-specific wording. The bolts in question hold the prop shaft bearing housing just forward of the prop into a retainer under snap rings. The bolts are "Allen" heads. Coincidentally, I did break one of the water pump housing screws and successfully drilled/tapped it.

Re: Evinrude lower unit bearing housing retaining bolt stuck

Bumpa53 said:

Guys,

Thanks for quick response.
My apologies for non-specific wording. The bolts in question hold the prop shaft bearing housing just forward of the prop into a retainer under snap rings. The bolts are "Allen" heads. Coincidentally, I did break one of the water pump housing screws and successfully drilled/tapped it.

Click to expand...

oooh, that's a tough one...and looking at the parts diagram, indeed looks like an allen-head (0313291). Practically zero working room there. :facepalm:

I wonder if you can just remove the bolt head entirely (EDIT: Duh...you tried that!) and deal with extracting the broken bolt once you get the retaining plate out. Keep in mind that the surface under that bolt head is a sealing surface (O-ring). So you'd either need a machine shop to clean-it-up -or- buy a new bearing housing (0384122 ~ $75). When drilling, you want to go very slow and use alot of cutting fluid to avoid getting frying/dulling the bit.