snapped main lower unit bolt at the threads

[Total Basshole]

I was trying to change the lower unit seals on my 1972 18hp model 18202 and the first bolt I tried to remove, the top bolt facing down, snapped off at the threads. Anyone know how I can remove this now? I am not sure what kind of sealant they used on the bolts but I would imagine I have to loosen that before I can remove the bolt. Suggestions to loosen the sealant and remove the broken bolt?

 

[1stgenbird]

Re: snapped main lower unit bolt at the threads

Drill and tap.

 

[1946Zephyr]

Re: snapped main lower unit bolt at the threads

Those are tough to remove, because they are stainless. It's not a sealer that's made it stuck in there, it's electrolysis. It's a nasty reaction that happens when stainless bolts are used in aluminum parts. They chose the lesser of two evils, when they bolted the motors together. Stainless bolts, was a little better than steel, because they won't rust out and be even harder to remove.

 

[boobie]

Re: snapped main lower unit bolt at the threads

Drill and tap it or drill the bolt out and install a heli-coil. DON'T try any E-Zee outs.

 

[Willyclay]

Re: snapped main lower unit bolt at the threads

DON'T try any E-Zee outs.

Why?

 

[boobie]

Re: snapped main lower unit bolt at the threads

If you're not used to using them and you break one off you're screwed. Can't drill them as they are very hard. Been there !!

 

[glenn property of pam]

Re: snapped main lower unit bolt at the threads

+1 with boobie unless you have experiance with a easy out its better to grind the bolt surface level then dot punch, drill and tap. i find a dremel seems to make the best pre-drill. use a cheapo easy out and you might have to buy a expensive diamond tip drill bit. been there done that......lol

 

[Willyclay]

Re: snapped main lower unit bolt at the threads

Good info, thanks!

 

[sschefer]

Re: snapped main lower unit bolt at the threads

If you want to do it right and have the money, find a machine shop with a EDM (electronic drilling machine). That will remove all traces of the old bolt and the you can re-tap it and put the original size bolt back in. Use a little zinc based anti-sieze this time and you won't have as big a problem next time.

You probably will blow this suggestion off until after you've screwed it up really bad trying to drill it out. That's cool. How do you think I learned about EDM's.

 

[glenn property of pam]

Re: snapped main lower unit bolt at the threads

a machine shop might be able to mig weld a nut on whats left of the stud. the heat is local to the bolt so the seals should be ok and it helps break the stud free. the trouble with a stainless bolt is that it can be heat hardened so if it doesnt work then its even harder to drill. edm is a great idea i just dont know of many shops that have the equipment and its costly to set up so i would request a quote first.

 

[Total Basshole]

Re: snapped main lower unit bolt at the threads

If you want to do it right and have the money, find a machine shop with a EDM (electronic drilling machine). That will remove all traces of the old bolt and the you can re-tap it and put the original size bolt back in. Use a little zinc based anti-sieze this time and you won't have as big a problem next time.

You probably will blow this suggestion off until after you've screwed it up really bad trying to drill it out. That's cool. How do you think I learned about EDM's.

LOL, a bit presumptive dont you think? I have actually done enough online research to know I would screw up the drilling/easy out. I dont know why I didnt think of it earlier but my brother in law is a welder in a machine shop and might be able to help me out for minimal expense. Thanks for the idea.

a machine shop might be able to mig weld a nut on whats left of the stud. the heat is local to the bolt so the seals should be ok and it helps break the stud free. the trouble with a stainless bolt is that it can be heat hardened so if it doesnt work then its even harder to drill. edm is a great idea i just dont know of many shops that have the equipment and its costly to set up so i would request a quote first.

Broken piece is recessed about 1.5" down the hole so I cant weld a nut on there.

Thanks for the suggestions everyone.

 

[boobie]

Re: snapped main lower unit bolt at the threads

I still have some left-handed drill bits in my tool box that I used for situations like this and they worked good.

 

[TrickyRicky]

Re: snapped main lower unit bolt at the threads

Been in a similar position with the stainless bolt broken. First get a decent set of cobalt drill bits. I recommend "Horrible Freight"They have a huge set of cobalt drill bits(like 3 sets in 1). If you catch it on sale and use there 20% coupon it is a great deal.Normally I wouldn't recommend buying tools from there but there are few good things to buy there. Just do what is already answered above. Get a sharp pointed stainless center punch and hammer a dot perfectly centered on the broken bolt. Then start with a small drill bit and carefully drill it. Some cutting fluid is a big help. When you drill through the bolt increase the drill bit size one at a time until you get close to the actual size of the hole. Then get a high quality tap and slowly cut the threads out to the original size.You will probably have to pick out threads some and keep blowing the hole out with compressed air. It will work if you take your time. I hope for you the bolt broke off straight and not angled. If it is broken crooked it will be a mother to drill straight. Be prepared to spend a good bit of time .Good luck