Gads, disaster! 2GM20 exhaust elbow bolt sheered off!

Martin_J said:
Richard


The photos that I posted links to earlier in this thread show my tool and the studs I extracted from a motorbike cylinder head. You will see my tool is identical to Vyv's tool and there was not a lot of room around the broken studs.
Click to expand...

Yes, thanks Martin I did look at your excellent bike photos. However, that broken stud is much longer than most of the broken studs or bolts that I seem to get lumbered with and you could probably have used Stilsons, although the Teng tool is clearly much better. I'm interested to see what happens with a stud or bolt which is just a few mm proud of the surface as those are the real killers because the mole wrench or Stilsons just tend to chew the end off completely.

Richard
 
Richard.. Indeed.. although in terms of cross section it was only about half a stud.

Fingers crossed for the OP, although once the pressure has been taken off the stud (by the nut shearing) the torque required to turn the remaining part 'should' be less.. :)
 
Update on mine. I must first point out that mine is a VP MD1. My winter shed project is to recondition it.
Two bolts came out easily, the third was already broken off with 1/8" protruding and the fourth, which I had assumed was just shorter than the others, is in fact broken off just below the surface of the head casting. I've now taken the head off and will drill out the two broken ones on my friends pillar drill.
Surprisingly, the head bolts came out fairly easily using a socket, tee bar and a short piece of galvanised pipe for extra welly.
I've still got to remove the fly wheel (massive chunk of cast iron),but that's a problem for another day. I've seeking a suitable puller to beg, borrow, hire or steal.
 
Okay, so there is good news and bad news. Lets start with the good, the two remaining bolts, after being soaked in PlusGas and having heat liberally applied, as well as a fair amount of bashing, came out. They are pretty corroded, so I am pleasantly surprised they came out:

hWHGgT8l.jpg


After a bit of cleaning up, the stud looks as below.

E6elpZJl.jpg


The bad news is, the M8 stud is so corroded, its diameter is more like 5mm after the extractor has compressed the threads, so the jaws of the stud extractor won't grip it and it just spins. I tried mulgrips briefly however rapidly chickened out when they started slipping for fear of making 5mms into 4mm. I retreated after reapplying heat and PlusGas to the stud to leave it to soak.

Any other ideas chaps? What about hammering a 3/16 one of these on?

http://www.axminster.co.uk/irwin-t394100-set-of-7-power-grip-screw-extractors

edit: Or one of these? http://www.ebay.co.uk/itm/like/311191226556
 
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MagicalArmchair said:
Okay, so there is good news and bad news. Lets start with the good, the two remaining bolts, after being soaked in PlusGas and having heat liberally applied, as well as a fair amount of bashing, came out. They are pretty corroded, so I am pleasantly surprised they came out:

hWHGgT8l.jpg


After a bit of cleaning up, the stud looks as below.

E6elpZJl.jpg


The bad news is, the M8 stud is so corroded, its diameter is more like 5mm after the extractor has compressed the threads, so the jaws of the stud extractor won't grip it and it just spins. I tried mulgrips briefly however rapidly chickened out when they started slipping for fear of making 5mms into 4mm. I retreated after reapplying heat and PlusGas to the stud to leave it to soak.

Any other ideas chaps? What about hammering a 3/16 one of these on?

http://www.axminster.co.uk/irwin-t394100-set-of-7-power-grip-screw-extractors

edit: Or one of these? http://www.ebay.co.uk/itm/like/311191226556
Click to expand...

Sorry to hear that the problem goes on Mark but at least it's only 1 problem and not 3!

I've used a similar extractor to the first one - a reverse spiral - to remove a stripped locking wheel nut. However, although I tried to use it with a spanner I couldn't get it to bite until I used an impact driver. I don't really like impact drivers as I'm worried that something will break and you do need good access.

The second tool looks like the Halfords one you linked to earlier but that might have been too big whereas the smaller one of the Laser set would definitely fit. The odd thing is that it calls them Impact Extractors but the photo shows an ordinary ratchet wrench being used! Probably you can use an impact driver but my first course of action is to use that as a final solution when all else fails.

My vote would be the Laser one with impact driving as an option if needed. The reverse spiral will need impact driving from the get go I'm certain.

Richard
 
Also commiserations but not entirely unexpected. If the bolt is so corroded in that the original head won't shift it, its no surprised that a mechanical gripper won't.
I'll try stillsons but expect to have to drill mine out.
 
Thanks Richard, I have ordered the set - lets hope I have more luck with the smaller extractor. My next option if this fails will be call a local engineer to see if they can get it out in situ. Hopefully the lengthy soak in plusgas will work its magic...

Ghostlymoron, well done getting your head off. You managed to source a puller yet? I would lend you mind if you were more local, its one of these:

http://www.justoffbase.co.uk/Hydraulic-Puller-Set-25pc-Sealey-PS982

Worked wonders getting my prop off: http://www.albinballad.co.uk/how-tos/fit-a-flexofold-propeller/ - a great well thought out bit of kit - not cheap though!!

IMG_7919.jpg
 
Thanks for the offer magical, but I don't think yours would get enough grip on the, slightly rounded, legs.
I've looked in the workshop manual and the puller has a 'special tool' number. Not much chance of getting one of those but all it is is a square plate with five threaded holes in it and appropriate bolts so fairly easy to make. The flywheel central boss has four threaded (m8) holes in it to which the special tool attaches. I'm hoping that applying some tension, waiting, dousing with plus gas, heating, clonking with opposing hammers will shift it.
 
I may have missed someone already offering such advice, but it may help to centre and start drilling a stud if you take a thick steel plate and drill a close fitting hole to drop onto the remains of the stud. Your drill cannot now wander off the stud and under a pillar drill it should be easy to get it central enough to drill out the core of the stud. I would never consider trying to drill out a stud without taking the head off and getting it under a pillar drill. As said above, when it goes back on you'll know that the valves are clean and nicely ground...

Rob.
 
rob2 said:
I may have missed someone already offering such advice, but it may help to centre and start drilling a stud if you take a thick steel plate and drill a close fitting hole to drop onto the remains of the stud. Your drill cannot now wander off the stud and under a pillar drill it should be easy to get it central enough to drill out the core of the stud. I would never consider trying to drill out a stud without taking the head off and getting it under a pillar drill. As said above, when it goes back on you'll know that the valves are clean and nicely ground...

Rob.
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It sounds as if you would use a drill and reverse thread extractor whilst there is still a few mm of stud proud of the surface. I would always persevere with that exposed stud as long as I could and Mark still has plenty of stud to work with. Once a stud is flush or recessed, a tap with a centre punch will normally centre the drill although I've never had a pillar drill so all my stud extractions have been with a handheld. However, I've always got it out in the end. Always with plenty of cursing though! :rolleyes:

Richard
 
You have my sympathy , as I stated earlier you are now in exactly the same position I was in last year. If you try and drill the remnants out in situ you will almost certainly stuff up the head, extractors I will just make what remains smaller. With mine same head and stud even welding on a nut didn't work it sheared flush, my 2p remove the head take to an engineering shop have them drill it out (decoke and reset the valves whilst your in there) best of luck . John
 
Tip from an Old Engineer
treat the seized bolt like a nail, Using a punch (just smaller than the bolt head) give the bolt a few hard whacks, this compresses/loosens the corrosion in the treads and helps the Plus Gas to penetrate. This does not work on all materials and should not be used on free standing cast Iron/steel parts, as you WILL break them, This method can be used on Nuts, with a hollow punch to shock the nut only and not the bolt/stud. Also hitting the nut simultaneously on opposing sides with two hammers, can work wonders - but does take practice. :)
Gas torch is good but, can heat up the stud + nut too quickly and maintain the grip, heating -cooling cycle - with patience - will normally win over seized parts.
Drilling out a broken stud is not rocket science but does take a modicum of manual dexterity and Patience and also more importantly a good quality / correctly sharpened drill bit and Quality stud extractors - Also start with a small pilot hole and use cutting / drilling paste.
Good luck - hope it goes well
 
I don't have huge experience of engine insides, but the mating surface around the stud looks terrible where I would have expected to see a nice smooth face for the exhaust-elbow gasket to seal against. Perhaps a previous owner refitted it without a proper gasket resulting in a slight leak and hence the corrosion of all the bolts?

Good luck with your continuing efforts :encouragement:

Pete
 
MagicalArmchair said:
… and PlusGas to the stud to leave it to soak. ...
Click to expand...

My commiserations, too – though pleased to hear it’s just the one. As a matter of interest, how do you (or others) ‘soak’ with the Plusgas on a vertical surface – do you make a Plasticine or similar ‘well’ for it around the bolts/stud? Or just apply heat and squirt it on – I’ve no feel for whether or not having a ‘reservoir’ of it is likely to make any difference.
 
Thanks all. I'm very much of your opinion Rob, John, that if it needs drilling, that head is coming off - and as others have said, that probably isn't a bad thing as I can then grind the valves etc. (not that I have ever done that before, however I did watch this with great interest: https://youtu.be/qp056LYvdRc). I do have a pillar drill (my late fathers, who was a shipwright/boat builder) and some very good cobalt drill bits, so I may have a try to drill it and use a stud extractor myself, that said, if I am in any doubt, I will take my PBO "I can do anything" hat off and take it into an engineering shop. I'm not as brave as you Richard for drilling in situ (or more likely, I'm just more cack handed!), I'm hanging my hopes on this Laser stud extractor...

Pete, yup, all very strange, its rusty underneath the elbow too, so clearly it has been leaking for some time from the gasget. There was a metal gasget there but in places that too was heavily corroded (and around that stud I am trying to get out it needed gentle chiselling to get it off the cylinder head)

To get a watertight seal I've been told silicon grease everywhere else (hole tails, impeller housing etc) and for very hot surfaces like this, to use copper grease on the gasget - does that sound like good advice?

edit: And talking of impact drivers for the Laser tool, if it comes to that, by jove, this air driven one kicks out 330Nm of torques http://www.axminster.co.uk/jet-jsm-4140-3-8-mini-impact-wrench for less than £70 - All the cordless ones come with a third of that power. Or I could go completely wild and get this one http://www.axminster.co.uk/jet-jsm-4343-1-2-impact-wrench which kicks out a cool 800Nm! :eagerness: ...mortgage won't be getting paid this month then... (and yes, I know, that stud will sheer off long, long before 330Nm of torque is achieved :D, the head came off with what felt like 50Nm of me gently leaning on it).

edit 2: I just sprayed it on and left it. Time to raid the office stationary cupboard then... good tip Pete...

edit 3 (cripes): Thanks raygin9. I did try a punch on it (and I attribute some of the success of getting the other two bolts out to that process), however I can't get much clout behind the hammer as access is a bit tricky on the stud. I will try some more cycles of heat/cold on it before I use the extractor.
 
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MagicalArmchair said:
edit 3 (cripes): Thanks raygin9. I did try a punch on it (and I attribute some of the success of getting the other two bolts out to that process), however I can't get much clout behind the hammer as access is a bit tricky on the stud. I will try some more cycles of heat/cold on it before I use the extractor.
Click to expand...

you can get centre punches that do not need hammering - spring loaded.

i have centre punched and hand drilled several siezed bolts - as long as the initial punch is centred well and you have decent small drill bits to start with its not so bad. esp if compression on head is fine, i would tend to leave well alone
 
MagicalArmchair said:
Quite so! Apologies, thanks for the tip too!! Now to try and find time to get down there to start said soaking process off...

Anyone have any thoughts on what to put on the exhaust elbow gasget when I finally refit? Copper grease the gollop to make it as water tight as possible?
Click to expand...

I always use silicone grease on hoses and rubber and copper grease on metal-to-metal gaskets and faces. I didn't confirm that in response to your post #56 in case it was my suggestion you were following in the first place. The last person you want to get a second opinion from is the person who gave you the first opinion! :)

The most important thing is thorough removal of all the old gasket crud from both faces.

Richard
 
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