Sheared bolt supporting alternator

[GH29]

The lower bolt/screw supporting my alternator has sheared off the engine block and Volvo advise that it is obsolete (photo attached). Two marine chandleries showed stock, but none available in reality. Screw part number: 3580014. I have trawled the internet to find one to no avail. I am in the process of extracting the sheared off end. It is almost certainly a metric thread M8 or M10 course pitch. I would very much appreciate suggestions and/or advice. Engine is a Volvo Penta MD 2030B 1998. Many thanks.

 

[Ink]

I would guess that Volvo don't make alternators.

I don't have a Volvo but someone here will have and know the make.

That widens your search and I'm sure a suitable bolt length and thickness will be found.

Ink

 

[Caraway]

Identify the thread and get a suitable bolt from a fixings supplier. There is nothing special about manufacturer's own bolts. If you fancy a shouldered bolt as is often fitted nip down to a scrap yard and get one from any number of car engines.

It isn't actually a shoulder bolt, but that's what it has been described as by the supplier of this one.

 

[pvb]

Yes, it should be easy enough to find a part-threaded hex bolt once you know what the thread is.

 

[paulajayne]

Do not use stainlees steel and it should be a t least 8.8 tensile strength.

 

[anoccasionalyachtsman]

You may already have discovered, bur sheared bolts often unscrew really easily now that the tension is off them. Try tapping it round with something sharp and a hammer.

 

[GH29]

Many thanks. I have also got an 'easy out' kit from Screwfix.

 

[anoccasionalyachtsman]

Many thanks. I have also got an 'easy out' kit from Screwfix.

Be very very careful - once an EasyOut has snapped you're in deep trouble.... Try everything else first. Heat, penetrating oil soaking for hours etc..

 

[jimi]

I had a similar issue with a stud bolt on the md2040. Drill snapped and I ended up spending 2 days drilling it out as a through bolt rather than stud bolt, which was a better solution anyway. Would have been easy if there wasn’t a bit of hardened carbon steel from the broken bit in the way!

 

[AntarcticPilot]

Don't use a stainless bolt. Mild steel is fine, but stainless ones will shear sooner or later. I found that out by using stainless bolts and having two shear before realizing that stainless is less resistant to shear stresses and more susceptible to metal fatigue than mild steel.

 

[Quandary]

I had one go on a VP 2003, not knowing any better I used a stainless steel one from the chandlers, it outlasted my ownership. I don't recall any difficulty with removing the old stub.

 

[AntarcticPilot]

I had one go on a VP 2003, not knowing any better I used a stainless steel one from the chandlers, it outlasted my ownership. I don't recall any difficulty with removing the old stub.

Mine was on a VP 2003, too, and they lasted less than a year each. Maybe it was a bad batch of bolts, but the replacement steel bolt has lasted many times as long. I did have fun removing one where the bolt snapped below the surface of the block... Fortunately, I had a set of Easy-Out bits!

 

[mainsail1]

Many thanks. I have also got an 'easy out' kit from Screwfix.

I would add to the words of warning about solutions such as easy out kits. They really are the nuclear option as if they go wrong, you are stuffed. I have very real experience of this!

 

[pvb]

Lots of people seem to be warning about the "easy out" method. Might it be worth using a Dremel to cut a slot in the stud first, then try using a screwdriver?

 

[AntarcticPilot]

Lots of people seem to be warning about the "easy out" method. Might it be worth using a Dremel to cut a slot in the stud first, then try using a screwdriver?

In the only case where I used an easy-out, the bolt had sheared below the surface of the block, and cutting a slot would have been more fraught with danger than drilling a small hole in the stub and using the easy-out. The bolt wasn't stuck; once I could rotate it, it came out easily.

 

[GH29]

Be very very careful - once an EasyOut has snapped you're in deep trouble.... Try everything else first. Heat, penetrating oil soaking for hours etc..

Very many thanks for this advice. An engineering friend will do the job and has already mentioned using heat etc. I shall pass this on.

 

[Daydream believer]

Drill down in to it with a couple of left handed drill bits first. Small then larger. You might find that it comes out whilst drilling. Then use an easy out if you must.
LH drill bit

 

[rib]

I'm not a argument guy. Nor am I a mechanic. Nor a metal expert... But..... I had two alternator m/s bolts shear on me 18 months apart. My custom made s/s bolt has lasted 3years thus far.. I am a liveaboard and generally (pre cov) thousand s of miles a year ?

 

[GH29]

Drill down in to it with a couple of left handed drill bits first. Small then larger. You might find that it comes out whilst drilling. Then use an easy out if you must.
LH drill bit

Great advice thank you. I have ordered the drill bits from the link. Many thanks.

 

[GH29]

Do not use stainlees steel and it should be a t least 8.8 tensile strength.

Could you explain why not to use stainless steel please. Thanks.