Broken outboard engine bolt - what method of extraction?

[StefanYHU]

ok guys i’m hoping for the opinions of experienced engine mechanics or builders.

I was about to start changing the water pump impeller.....the bolts felt welded solid, I managed to get one out and the other I left in penetrating oil for fear of breaking it.....but when I finally got to it, it did indeed snap.

Luckily not in the worst area where a bolt could break on the engine but it has scared me now that I could break another. I don’t have much experience with outboards but do with cars/bikes....typically I’d use for blowtorch for steel in this scenario but with alloy, does anyone on heruse heat?

the impeller has never been changed, the engine is 25 years old and has been used in the salt.....

as for extracting the remains of the bolt....drill it? When I move the jacket by hand up and down, I can see the end of the bolt on the reverse side rotating.

bit of a bummer as I need to have the engine going by next Friday or my fishing trip is over!

thanks guys

 

[Caraway]

Be very helpful to say what make and model and age the outboard is.
Pics are very helpful as well.

 

[StefanYHU]

 

[StefanYHU]

25 year old Honda bf8a, I was removing the cover to get a look at the gear linkage.

There is a certain amount of movement now with the bolt out on one side...so when you move the cover up and down, I can see the bolt rotating from the back

 

[Caraway]

Is this the Honda 8 you asked about previously?

Are those large bolts the ones you need to remove? This shows the procedure. Honda BF8D-BF20D Water Pump Impeller Replacement Only 10mm bolts are mentioned.

I'd have gone for the service you mentioned in the other thread.

 

[StefanYHU]

Is this the Honda 8 you asked about previously?

Are those large bolts the ones you need to remove? This shows the procedure. Honda BF8D-BF20D Water Pump Impeller Replacement Only 10mm bolts are mentioned.

I'd have gone for the service you mentioned in the other thread.

I almost did leave it to the person who quoted me for the service....then a friend sent me a link to his previously liquidated marine company, and the large amount of people claiming he either damaged their engines or those who claimed he never actually done the work and charged them for it....

on top of that, he claimed he could do all that work with genuine Honda parts and give it back to me in the same day, sounds great....except the biggest Honda marine dealer here here in Northern Ireland doesn’t even hold stock for an engine of this age....so it’s fairly certain I was going to be shafted!

Thanks for the DIY, so I’ve removed the bolts for an area didn’t need too.........that’s not so bad, as it means I can still get this serviced in time. I can put the other bolt in and that will do rightly until I’ve free time to extract the bolt.

so how do I ensure these other bolts don’t suffer the same fate, they have never been removed..... do you guys reccomend heating bolts?

and in terms of bolt extraction, I’d be glad to hear from the pro’s.....

 

[philwebb]

Centre punch the bit of bolt left behind. Drill out the centre with the largest size drill that you can get in without getting too close to the threads.Now use the largest size stud extractor you can get into the stud and carefully ease it out. If you can get hold of an aerosol of “crack-it” that will help extraction. It is penetrating oil with freezer gas that will shrink the stud a little and help the oil get into the thread.
If you damage the soft metal casing the solution is to fit a “helicoil” to remake the thread.

 

[Caraway]

Just done an extraction of two 5/16" bolts in threaded holes in a steel plate. When I say extraction I just drilled them out to just under the tapping size and used a taper tap to remake the threads. As it was into steel the tap just wound the remains of the bolts out of the other side of the threaded plate. I've never used easy-out type extractors. They have a reputation for snapping.

With these being into alloy I would be a lot more careful. Perhaps just plan on having helicoils put in.

 

[Graham376]

If the bolt shears in such a way that you can't centre a drill, a quick grind with a Dremel often solves that, then drill out and Helicoil if necessary.

 

[William_H]

One note of caution. The bolt is almost certainly a stainless steel. So drilling the bolt out will require a good drill bit lots of pressure and lubricant. Don't let the bit run off to the side into the ali. Do not let it get hot. The SS will work harden. Fortunately the inevitable heat will tend to release the bolt. good luck ol'will

 

[TernVI]

If the bolt shears in such a way that you can't centre a drill, a quick grind with a Dremel often solves that, then drill out and Helicoil if necessary.

Yes, the dremel is useful to grind a centre mark, or to re-centre the drill.
I've had some success using left handed drills to extract small bolts.

 

[Graham376]

One note of caution. The bolt is almost certainly a stainless steel. So drilling the bolt out will require a good drill bit lots of pressure and lubricant. Don't let the bit run off to the side into the ali. Do not let it get hot. The SS will work harden. Fortunately the inevitable heat will tend to release the bolt. good luck ol'will

I expected my Tohatsu to use stainless but they weren't.

 

[RichardS]

One note of caution. The bolt is almost certainly a stainless steel. So drilling the bolt out will require a good drill bit lots of pressure and lubricant. Don't let the bit run off to the side into the ali. Do not let it get hot. The SS will work harden. Fortunately the inevitable heat will tend to release the bolt. good luck ol'will

I recently bought a tube of professional cutting compound for drilling steels. The difference it makes compared to using oil or WD40 or whatever is amazing. I've been drilling dozens of holes in steel over the last few weeks and it's been child's play.

Richard

 

[Rappey]

I've used left handed drill bits in the past as sometimes they grab the snapped stud and unwind it.