BajaNomad - removing sheard bolts from aluminum lower end?

removing sheard bolts from aluminum lower end?

Santiago - 3-20-2016 at 12:47 PM

15 HP 2 stroke Yammie from the early 1980s. The two back bolts that hold the impeller housing have sheared off causing me to say "Shoot" real loud.

Neighbor ran over to see what all the ruckus was and he said they will never come being salted in (Dad ran this in salt water a lot.)
We started wondering if they are really needed; after all, if a little water gets in the lower end gear oil is sealed.
Then another guy walks up and says to simply drill them out and JB Weld in a bolt that has the head cut off and use a nut. Hmmmm, that might work.
What say you?

[Edited on 3-20-2016 by Santiago]

rts551 - 3-20-2016 at 12:51 PM

Use an easy out. then chase the threads with a tap.

Fernweh - 3-20-2016 at 01:04 PM

Easy Out...it is only the name, it's never easy out, especially with salt water corrosion.
I would drill them out, starting in the center for sure, with a small bit first, and then go larger, step by step. If your lucky, you can peel out the remaining threads.
Re-tap the the bores again or use a thread insert if needed.

Make it as nice and precise as possible, remember, you need to have the coolant water being pushed up all the way into the hot head :yes:

larryC - 3-20-2016 at 01:09 PM

I agree with rts, but along with the easy out you will probably have to use some heat. It looks like you could get a torch in there beside the broken stud and heat the aluminum up some to help loosen the broken stud. You have to be very careful when you drill the stud to stay in the center of it. Might also have to use a cobalt drill bit and start with a center punch and center drill. Not an easy repair. Is it a 6mm bolt? 6mm is a little smaller than 1/4". Not much material to work with.
Good luck with it.

PaulW - 3-20-2016 at 01:24 PM

Use an ezout an break it off and then you have a real issue. EZouts break very easily and leave the hardened remains inside so you cannot use a drill.
Based on your using it in salt I would grind it flat and drill it out and use the next size larger tap and bolt. If you are lucky you might even save the original threads.
Irwin and Sears sell the reverse drill bit with a conical starter that probably will not break off it if the thing is really stuck. I would try that tool before drilling. Still you need a flat surface and a center punch.

larryC - 3-20-2016 at 01:39 PM

One other method might be to remove the stainless water pump plate to give you a little more clearance and then take it to a good welding fabricator and have them tig or mig weld a nut (on the inside of the nut) to the exposed broken stud and some heat and they may be able to get it out that way. Just the heat from the tig/mig weld will probably be enough heat to break the salts loose that are holding the stud in place.

Bob and Susan - 3-20-2016 at 01:40 PM

don't do it yourself...drive it over to a machine shop...bite the bullet
you ONLY get one chance not to "screw" this up

willardguy - 3-20-2016 at 01:53 PM

where's captkw when we need him?

ncampion - 3-20-2016 at 02:11 PM

If there's a little bit of the bolt protruding above the surface, which it looks like there might be, you can make a "centering jig" with a peice of 1/4" metal that bolts in place of the water pump plate. That let's you drill right down the center of the bolt. Otherwise it's very difficult to drill in the center which is necessary to do it right. You may still need a thread insert when it's all done. I always use a little Anti-seize on SS bolts that go into saltwater motors.

LancairDriver - 3-20-2016 at 02:15 PM

I own a machine shop and we do hundreds of sheared and broken bolts and taps in a year. From the picture it looks like you start with a sharp tip punch to allow you to center a spot on the broken bolt to start drilling. This method uses the most common tools you may have available. Start with a smaller drill and work up to a larger one. If you are able to open a hole large enough you will be left with a thin wall of the remainder of the bolt. This can then be carefully chipped out with a small screwdriver without damaging the threads. Running a tap to chase the threads and clean them may be necessary. An easy out would require a fairly well centered drilled hole and then an easy touch to work the easy out without breaking it and making the problem worse. A good penetrating oil applied before any of this will help a lot with the corrosion sure to be there.
Some auto repair and machine shops have portable EDM (electrical discharge machine) to burn the bolt away which works the best if you have access to this.

mtgoat666 - 3-20-2016 at 04:21 PM

Quote: Originally posted by Santiago

Take it to a machine shop!

I often amuse myself when I start a home DIY project and then break the widget, and end up taking the project to a professional to fix my mistake :lol:

dtbushpilot - 3-20-2016 at 04:32 PM

What LancairDriver said, have done it many times. If you don't have the tools or experience with them it would be best to take it to a machine shop and save yourself a lot of grief.

Oops !

captkw - 3-20-2016 at 04:35 PM

start by removing the "wear plate" that's the s/s the 4 bolts went thru..it will come with a gentel touch of a chisel...then grid the top of the bolts as flat as you can without hitting the aluminum that is a sealing area..then Center punch in the very,very center of broken bolt..using a air drill.. drill completely thru bolt if possible but not more.. get a can of areokroil, stick in red tube and start soaking from both ends...now, you can start driver larger and larger drill bits.. then decide how long you can soak and what size to drill up to.. hit the easy out in with a GooD "Whap" of a small hammer.. Say Loud prayer and give it a try and you will get the feel for it.."Wish ya luck"ps reinstall with bolt coverd in a marine grease...

55steve - 3-20-2016 at 04:50 PM

I usually just weld a nut onto the stud....the heat generated helps loosen it. This process may have to be repeated a few times but it always works for me.

Don't use never-seize when reinstalling - marine grease is best - my friend (marine mechanic) swears that moly-based grease is the way to go though.

[Edited on 3-20-2016 by 55steve]

wessongroup - 3-20-2016 at 04:51 PM

EDM (electrical discharge machine) ... they work sweet .. the true easy out ... thx LancairDriver

[Edited on 3-20-2016 by wessongroup]

Santiago - 3-21-2016 at 05:27 AM

Everyone's ignored the idea that came up to just forget about the back bolts; is that because it's stoooopid? Heh, prolly so.

larryC - 3-21-2016 at 08:58 AM

Quote: Originally posted by Santiago

Everyone's ignored the idea that came up to just forget about the back bolts; is that because it's stoooopid? Heh, prolly so.

That would be my last choice. Weld a nut to the stud and it will probably come right out.

jayme - 3-21-2016 at 09:10 AM

Ditto to the welded nut. If the bolt is broke flush, weld a washer on the broken stud, then weld a nut to the stud. That is the fastest way, and if that breaks off, the stud can be drilled

Udo - 3-22-2016 at 10:15 AM

IF the bolts are not totally frozen in place, you may center-punch the bolt at dead center and drill in incremental sizes (sorry of the big word) with a left-handed drill bit and the bolt may just come loose right away. However, in past experience, use WD40 or other penetrant (for obvious reasons the bolts have to be in upright position) for at least 24 hours prior to attempting the drill method.
You can buy left-handed drill bits (good quality) if you google the word.