Getting broken bolt out of engine block

wannabecraig · 26-03-2021 04:56PM #1

One of the two bolts that hold my starter motor in place on my 3trl boat engine has broken inside the engine block. This is on the underside of the engine, about 6" from the floor, so I can't get a drill at it to drill out the bolt. If I were to drill it out, I'd have to remove the engine,. This is a nightmare and I'm not up for it.

I was thinking of putting in another screw with Araldite for steel or Gorilla Glue Epoxy on the top and hoping it would catch the broken piece of the screw and bond, then I could remove the screws.

Is this likely to work? Do I have any other options?

TIA

26-03-2021 05:01PM

Could you use a flexible drill extension and the drive in bolt extractor?
https://ie.rs-online.com/web/p/drill-accessories/6685868/?cm_mmc=IE-PLA-DS3A-_-google-_-CSS_IE_EN_Power_Tools_%26_Soldering_%26_Welding_Whoop_HI-_-(IE:Whoop!)+Drill+Accessories-_-6685868&matchtype=&pla-337623657253&gclid=Cj0KCQjwjPaCBhDkARIsAISZN7SkW9_9HRurUTMvFKACMsiYpZt2xQq13pt-_3lZ6_IDrJt33FxXVgMaAg-FEALw_wcB&gclsrc=aw.ds

https://www.screwfix.ie/p/bolt-extractor-set-5-pieces/1112V?gclid=Cj0KCQjwjPaCBhDkARIsAISZN7ShU0z6bvie3HVrLhdgBbA54xnEwCGl4iIWQuia8H-ZMk8sH5PH_SYaAgABEALw_wcB&gclsrc=aw.ds

The Continental Op · 26-03-2021 05:09PM

If the bolt sheared off I wouldn't expect any form of epoxy to be strong enough.

greasepalm · 26-03-2021 05:15PM

No thinking you would make life harder if you tried to bond it,

I would ask did the bolt sheer in trying to loosen it or fail by vibration?

If the threads are clear i have got a narrow spring loaded centre punch to assist rotation anticlockwise.

If its seized in there with rust you will have a job in your hands.

The Continental Op · 26-03-2021 05:21PM

Really daft question but worth asking is this a blind hole or does the bolt thread stick out the back of it.

Sometime you can get lucky where a bolt goes all the way through a housing and out the other side so you can work on the bit that sticking out.

wannabecraig · 26-03-2021 05:23PM

The bolt sheered off due to vibration.

So are we saying, use the punch, then the tools above , flexible drill extension and bolt extractor?

I guess blind. It goes into the engine block but that hole doesn't go all the way through.

The Continental Op · 26-03-2021 06:03PM

Bolt extractor is the way to go if you can drill a hole but beware if you haven't used one before the cheap ones that are easily available are very prone to snapping so use the largest one you can and do not apply too much force. I've had your situation plus the end of a hardened steel bolt extractor snapped off in the hole. Try drilling one of them out. I had to drill around the edge of the bolt then when it was finally out redrill and retap the hole for a larger bolt.

If the end is near the surface then welding a bit of steel bar is another solution but can also cause more problems if messed up.

Curious_Case · 26-03-2021 06:11PM

Is the sheared end of the broken bolt deep enough to allow the starter motor to be held by a shorter bolt ?

phelixoflaherty · 26-03-2021 06:11PM

Any other bolts in the general area.
If so make up a steel plate ( could be angled to go around corners to get another bolt)
Bolt the plate on and mount alternator off this.
If it works u may need a slightly bigger fan belt.
Hopefully you can understand this

stratowide · 26-03-2021 06:23PM

What size thread is the bolt.?
Does the engine block have dowels that the bolts go through.

Was the bolt that came out loose all the way..?
Is the broken bolt flush with the block..?

If you can see the sheared bolt try a centre punch and hammer and gently tap it anticlockwise.
It might come out enough to get a vice grip on it.

If the bolt is 12mm or more can you see enough of it to weld something onto it and extract it that way..?

CoBo55 · 26-03-2021 06:48PM

phelixoflaherty wrote: »

Any other bolts in the general area.
If so make up a steel plate ( could be angled to go around corners to get another bolt)
Bolt the plate on and mount alternator off this.
If it works u may need a slightly bigger fan belt.
Hopefully you can understand this

It's holding the starter on...

wannabecraig · 26-03-2021 08:02PM

To answer all questions.

Bolt is sheer, maybe even a little bit inside the block, so no grip.
I'll take pics tomorrow so show how hard it is to access.
Cannot hammer punch in as there is no distance to get good swing. Gap between bolt opening and floor is about 6".
Will get auto centre punch from Amazon and try that, hopefully it'll loosen it up a little.
Right angle drill bit holder might work to get bolt extractor on it.
https://www.screwfix.ie/p/erbauer-angled-bit-holder-160mm/9929v
These bolt extractors get decent reviews, willing to pay more, not sure where else I'd get one?
https://www.screwfix.ie/p/screw-bolt-extractor-set-2-pieces/2951v

This is replacement bolt https://marineparts.ie/short-bolt-10-812509184/

This is mine currently. 1 thread left!
Sr5a1Tq.jpg?1

If there was a way just to fasten the starter motor onto the engine as before I'd be willing to do that also.
Weld, glue etc.

Also willing to hire somebody to come out and do the job for me if anybody has any suggestions on that.

stratowide · 26-03-2021 09:25PM

The splines on that bolt would suggest it is pushed/hammered in and the nut on the other side should be removed a la wheel studs.

Try to spray some wd-40 on the broken bolt and leave overnight.

A sharpened screwdriver or similar and hammer into it and try turning.
You'd be surprised how easy it might eventually come free.

greasepalm · 26-03-2021 09:30PM

If the bolt can move i would try some wd40 to help it release.

https://www.amazon.co.uk/Starrett-18A-Automatic-Centre-Adjustable/dp/B0006J4Q64/ref=asc_df_B0006J4Q64/?tag=googshopuk-21&linkCode=df0&hvadid=309815944779&hvpos=&hvnetw=g&hvrand=5038196227997087462&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007850&hvtargid=pla-521886027539&psc=1

Other thing you might have to hand is a long nail with a sharp point to try and rotate broken bolt out anticlockwise by putting nail in the hole out to the edge and hope it will grab a burr and rotate anticlockwise before matters get worse.

CoBo55 · 26-03-2021 10:34PM

What are the serrations for on the plain section, do they grip the drilled lug on the starter in any way?

greasepalm · 26-03-2021 10:50PM

Possible its to centralize the starter position as some cars starter can move slightly to adjust position.

listermint · 26-03-2021 11:14PM

With 6 inches of clearance .

You'll absolutely wrack your brain getting this out and I'd garner with f all success.

Bite the bullet and lift the engine out or up enough for clearance to drill.

I wouldn't bother any other half arsed options it will just waste time til the inevitable.

Dupont · 26-03-2021 11:22PM

Put a nut over the broken stud and weld it to it. The heat will also help a lot to free it when turning it then.

Vestiapx · 26-03-2021 11:26PM

Dupont wrote: »

Put a nut over the broken stud and weld it to it. The heat will also help a lot to free it when turning it then.

It's below flush

Del2005 · 26-03-2021 11:35PM

listermint wrote: »

With 6 inches of clearance .

You'll absolutely wrack your brain getting this out and I'd garner with f all success.

Bite the bullet and lift the engine out or up enough for clearance to drill.

I wouldn't bother any other half arsed options it will just waste time til the inevitable.

This. If you aren't up for removing the engine pay someone to do it.

greasepalm · 26-03-2021 11:40PM

I would only do that if knowing 100% its not moving.

Curious_Case · 27-03-2021 12:19AM

Could some form of extended "C" clamp be fashioned from a length of steel?

One of the returns could be drilled and secured to the starter at the bolt hole,
the other return (also drilled) could, perhaps, bolt to the engine wherever possible.

Tokyo · 27-03-2021 05:59AM

You might get lucky with a bolt extractor, but my bet given what you described is that you will need to drill it out and re-tap it, or just run the risk of doing more damage. Which means you'll need to lift the engine to some degree.

wannabecraig · 27-03-2021 12:11PM

The issue with removing the engine is not jus the cost. Marine mechanics are out the door right now, the next time I can get somebody to even look at it is mid-April. Just to give you a gauge of costs though, it'll prob cost about 800€, so avoiding that would also be nice.

If I could even get any other way of sticking the motor onto the block that wouldn't move I'd probably go for it.

I'm going to try the other methods because I have the time, I dont think I can do too much damage.

daveville30 · 27-03-2021 01:41PM

Put up a picture of whats left of the bolt.

wannabecraig · 27-03-2021 03:43PM

https://imgur.com/EOdkxH1

Circle is where missing bolt is, as you can see from video the motor doesn't move over far enough to get access to
get a shot of the bolt stuck in the engine block. The starer motor could come off easily enough, just one other bolt to remove.

Again, motor doesnt go over enough to get clean access to the hole that receives the bolt.

This is the only undershot I can get, as mentioned, starter doent move over enough to see actual hole.

Tokyo · 27-03-2021 03:47PM

Any chance of an underside shot?

The Continental Op · 27-03-2021 03:52PM

How big is that sheet metal access plate below the starter? I'd take the starter out that plate off and take a look at what's accessible on the inside.

wannabecraig · 27-03-2021 03:59PM

The Continental Op wrote: »

How big is that sheet metal access plate below the starter? I'd take the starter out that plate off and take a look at what's accessible on the inside.

Is that the thing that's blue with black spots? If so, that's the bottom of the boat and is not removable.

daveville30 · 27-03-2021 04:07PM

Could you drive a tek screw down on to the snapped of piece of bolt.and unscrew the the broken piece with the tek screw

stratowide · 27-03-2021 04:08PM

wannabecraig wrote: »

Is that the thing that's blue with black spots? If so, that's the bottom of the boat and is not removable.

No its the semi-circular plate directly under the starter.Will that come off..?

Have you had the starter actually out or is something still holding it..?

Is there any access from the other side i.e. gearbox,bell housing or drive train..?

Getting broken bolt out of engine block

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