Getting broken bolt out of engine block

wannabecraig

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

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

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

greasepalm

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

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

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

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

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

phelixoflaherty

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

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

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

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!


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

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

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

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

greasepalm

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

listermint

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

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

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

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

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

Curious_Case

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

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

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

Put up a picture of whats left of the bolt.

wannabecraig

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

Any chance of an underside shot?

The Continental Op

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

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

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

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..?

BorneTobyWilde

Could you not drill straight through, from top, put a bolt and nut on it then

BorneTobyWilde

I'd drill it from top, put a stainless 10mm bolt and nut on it.

The Continental Op

OK so I think I understand this now?

The bolt goes in vertically from underneath and the threaded hole is inside the big chunk of cast iron on the side of the engine.

The Continental Op

BorneTobyWilde wrote: »

Could you not drill straight through, from top, put a bolt and nut on it then

Good idea but I think it needs a good bit of preparation and thought?

I'd consider grinding a flat where you have put the arrow first to get the drill started and then perhaps grind a curve back when finished for stress relief.

Its going to need careful centering and I would start off with a small pilot hole. Long drills are going to be needed to drill a straight hole.

Also as you suggest no need to thread the hole as a nut on a long bolt will secure it.

stratowide

The Continental Op wrote: »

OK so I think I understand this now?

The bolt goes in vertically from underneath and the threaded hole is inside the big chunk of cast iron on the side of the engine.

Ah yes thats it I think.Bolt and nut so if he doesn't mind drilling that plate.

Tokyo

BorneTobyWilde wrote: »

I'd drill it from top, put a stainless 10mm bolt and nut on it.

Looks like it will have to be drilled at an angle though, through what looks like a couple of inches of cast iron, plus presumably through the remnants of the bolt stuck in the block, and hopefully all will line up.

Best case scenario, it will be an awful bodge of a job, and not one easily undone in future should he lift the engine out and want to set it right.

Not my engine, but if it were, I'd be looking at making some kind of bracket using other existing bolts or bolt holes on the engine block, or possibly welding a tab onto the starter motor and bolting op the starter for now until opportunity to lift the engine out. Though if an engine hoist could be borrowed, I'd probably just bite the bullet now. Engine doesn't have to be lifted out completely, just enough clearance to get access.

The Continental Op

Certainly not a job to be undertaken lightly.

The Continental Op

OK so here is how I'd go at it Plan A, B and C.

Assumptions: The bolt broke off in service therefore the piece that still needs to be removed isn't rusted in place. Looking at the bit of the bolt that came out that isn't too much of a stretch.

Plan A drill out minimal size hole in the bolt from below and use a small extractor using very little torque. If that fails go to Plan B

Plan B drill out a the original hole making it larger so you can use the max size extractor and apply a lot more torque, but still not over doing it.

Plan C is to go down from the top.

So for Plan A or B you need to be able to get a right angle drill in under neath something like https://www.amazon.co.uk/DeWalt-Lithium-Ion-Cordless-2-Speed-Batteries/dp/B0051HE3XC/ . Now if you have only an inch to spare then you can grind the shank of a drill down to shorten it so you can get a start. The key to this is to use a guide in the hole to make sure the drill is drilling into the center of the bolt. As an illustration this is something like you need https://www.amazon.co.uk/Woodworking-Drilling-Oblique-Positioner-Locator/dp/B07D9LSWPH/ a round section with a hole in the middle a little bigger than the drill bit you are using. The guide needs to fit nicely into the hole. I'd start with a 2mm hole and be very very careful not to break the drill bit off in the hole (nightmare!!) go in no more than 15mm then try gently with an extractor. If that doesn't get any movement now you have a pilot hole you can drill out to say 5mm or even bigger. The size of drill you use will probably be dependant on the size of guide you can find. Best not to try this without a guide!

Plan C is as already mentioned from the top.

Some good info here

wannabecraig

stratowide wrote: »

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..?

I cant take taht plate off no, part of the engine.

I can take the start off, it's currently being held by the other nut, long nut on the other side.

There is no access from the back.

The Continental Op

wannabecraig wrote: »

I cant take taht plate off no, part of the engine.

I can take the start off, it's currently being held by the other nut, long nut on the other side.

There is no access from the back.

Think we are passed that now anyway provided we have got the position of the bolt right. Its all down to how much access you have to it under there.

wannabecraig

I don't want to drill into the engine, happy to take it out, or get it taken out, I just can't get anybody to do it soon.
I really want to try to get the screw out, so I'm going to go with plans above.
Spoke to a mechanic today and he warned me about drilling blind into that screw, said Really want to make sure
it doesn't go into the block itself. But I might just take a shot!

Instead of buying an angle drill, would this do? https://www.screwfix.ie/p/erbauer-angled-bit-holder-160mm/9929v

Will go through video above and see if I can get it done that way.

Really grateful for all advise so far, lots to work on.

wannabecraig

The Continental Op wrote: »

OK so I think I understand this now?

The bolt goes in vertically from underneath and the threaded hole is inside the big chunk of cast iron on the side of the engine.

Yes, this is exactly it, sorry for lack of clarity.

wannabecraig

BorneTobyWilde wrote: »

I'd drill it from top, put a stainless 10mm bolt and nut on it.

It that not a little extreme? It's fixable, I just want to give it a small pop myself before I have to pay to get the engine taken out.

The Continental Op

wannabecraig wrote: »

I don't want to drill into the engine, happy to take it out, or get it taken out, I just can't get anybody to do it soon.
I really want to try to get the screw out, so I'm going to go with plans above.
Spoke to a mechanic today and he warned me about drilling blind into that screw, said Really want to make sure
it doesn't go into the block itself. But I might just take a shot!

Instead of buying an angle drill, would this do? https://www.screwfix.ie/p/erbauer-angled-bit-holder-160mm/9929v

Will go through video above and see if I can get it done that way.

Really grateful for all advise so far, lots to work on.

The problem with that is where is the chuck to hold a drill? You'll need to get some suitable size drills with a hex head on them an example https://www.amazon.co.uk/LESOLEIL-13pcs-1-5-6-5mm-Titanium-Coated/dp/B01D30D2IA/. The downside is you can't sorten the shank on them.

However you do it you need some form of guide, because you can't see what you are doing but I suspect you can check if you are drilling squarely into the bolt.

BorneTobyWilde

wannabecraig wrote: »

It that not a little extreme? It's fixable, I just want to give it a small pop myself before I have to pay to get the engine taken out.

No harm in drilling it from top, it's just steel. Grind it more flat, and a tad wider. Use small bit and drill straight through, use bigger bit as you go to widen it until it can take a bolt.

It's not the correct fix, but done right it's a solid one. Need pro cobalt bits.


Best to try everything else first. Who knows it might come out easy.

greasepalm

Have you tried the easy way yet with starter motor removed?

wannabecraig

greasepalm wrote: »

Have you tried the easy way yet with starter motor removed?

NO, I'll be trying this on Monday. I've never done this before so being cautious.

wannabecraig

The Continental Op wrote: »

The problem with that is where is the chuck to hold a drill? You'll need to get some suitable size drills with a hex head on them an example https://www.amazon.co.uk/LESOLEIL-13pcs-1-5-6-5mm-Titanium-Coated/dp/B01D30D2IA/. The downside is you can't sorten the shank on them.

However you do it you need some form of guide, because you can't see what you are doing but I suspect you can check if you are drilling squarely into the bolt.

I have a drill set with HEX heads but I can go an buy a decent metal on too.
https://www.screwfix.ie/p/dewalt-hex-shank-cobalt-hss-drill-bits-8-x-117mm/3713v
It's a M10 bolt in there so not sure this is the correct size

gutteruu

Might be a bit rough, but can you just put a few spot welds on the side the bolt is broke, holding the new starter to block (being careful not to crack block with heat). Could always just grind them off next time the engines out or you want to change it. Hard to see how you'll get it out if its lodged well in there and you've only 6 inches to play with.

listermint

Surely hoisting it out a foot or so is the smartest option. You should get to grips with your engine back to front as there's no marine mechanics with you out on the water. Taking off the drive unit and other bits and lifting it will get you more acquainted with the workings.