Johnson 6 HP - 1967- sheared bolts.

[budgey]

Despite the alternate use of heat and penetrating oil, the 42 year old bond between stainless steel bolts and aluminium casing proved to strong for four the eight 1/4" UNC bolts holding the rubber mounts to the shaft housing of my 1967 6 hp Seahorse.

I've now drilled them out and am trying to remove them with an "easyout" stud extractor. But I fear I am getting perilously close to the ultimate torsional strength of the extractor. Not wanting a sheared off extractor to spoil my day, I will now resort to re-tapping and thats where I need the advice from someone more experienced.

I have never used Helicoil inserts, but it strikes me as a good system. Then the stainless Helicoil should bond with the aluminium and the interface between the bolts and the Helicoil will be between similar metals and should prove easier to remove in 2051, the next time these bolts are likely to come off.

Or should I just drill out the old bolts to 13/64" and re-tap a 1/4" UNC thread in the housing and then use grease when re-assembling? Which brings me to the second part of my question. Would it be advisable to use grease on these bolts or could they shake themselves free - in which case Loctite would be better?

 

[jbjennings]

Re: Johnson 6 HP - 1967- sheared bolts.

I believe a little dab of gasket sealant on those bolts is best. The grease and loctite are nono's.
JBJ

 

[F_R]

Re: Johnson 6 HP - 1967- sheared bolts.

You are wise to get rid of that easy-out. There is no such thing as an "Easy-Out". It isn't easy and it won't get it out. Breaking that thing off in there will ruin your whole day. Same thing for a thread tap. DO NOT run a tap in the hole while there are any bits of the old screw in there. It will jam and you won't be able to turn it in or out, and you will break it--again ruining your whole day.

A Heli-Coil is the way to go. Grease or gasket sealer on the bolt is ok to help prevent future corrosion, but is not a magic cure-all, especially in salt water. I disagree with the previous statemant concerning locktite. The blue screw-lock grade a fine sealer to keep water (and corrosion) out of the threads. But you probably shouldn't use it on a bolt going into a Heli-Coil.

 

[budgey]

Re: Johnson 6 HP - 1967- sheared bolts.

Thanks for the advice. Looks like Helicoil is the way I'll be going.

 

[iwombat]

Re: Johnson 6 HP - 1967- sheared bolts.

When you do drill them out, use a left-hand drill bit. You'd be surprised at how often they just spin out.