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

[RichardS]

New stud extractor arrived, and no luck. It requires the stud to be longer in order to be effective at 5mm on the 1mm to 6mm stud extractor.

To add to the fortunes spent already on trying to remove this, next up we have these: http://www.axminster.co.uk/irwin-t394100-set-of-7-power-grip-screw-extractors (the 3/16s one being the only one I am interested in of course).

I will be consulting http://www.kentmarineservices.com/ tomorrow also as I am somewhat losing hope and succumbing to despair! How hard is it to get the head off the engine if I do go for this nuclear option? Any decent guides that can be suggested?

I'm really sorry to hear that Mark. Is it like a drill chuck where the gripper jaws extend outwards as you close the distance between the jaws as I guess that would mean that the more open the jaws are, the further they are inside the body of the extractor.

How long would the stud have to be to be grippable in the smaller extractor?

Would the larger extractor extend it's jaws sufficiently to grip the stud, assuming that the stud was a bit thicker and that it could grip it at all?

If the answer to the second question is yes then you need a way to widen up the stud so that the larger extractor, or perhaps even the first one you bought, can get a grip.

The obvious answer is to weld some welding rod onto the side of the stud to build it up a bit but I realise that you're not going to be able to do that. What you might be able to do is take something like a very small size rat-tail or flat file - for example - I have one which is only 2 or 3 mm square, and cut some short lengths which you can insert into the jaws of the extractor before clamping it onto the stud. Try with one piece of file first.

A file sounds ideal because it is hard and rough but you might even try with a single flat nail or similar which you just slot down one side of the jaws so the teeth on the other side are still biting into the stud at least on one side because the smooth nail will not grip the stud.

It's worth a try as it's very low cost!

Richard

 

[nemodreams]

You could have the head off in an hour or so !
Use the opportunity to properly decoke the exhaust port - grind the exhaust valves - only expense is a new head gasket.

Any local motorcylce repairer will whip the old stud out in five mins - with the head on the bench.

 

[MagicalArmchair]

As Richard says Bikedaft, as I can only get access to the stud from the side, I wouldn't be confident drilling the little sucker out without taking the head off. The compression is awesome on the engine, so I am very reluctant to take the head off apart from as a very last resort.

I used the blue tack well idea (thanks chaps) and left it for a few hours (I have left the well in place now too so it can soak for a week).

Richard, yes, it works exactly like a drill chuck and the jaws of the smaller one are too far inside when working at its upper limits.

I did try something like your shim idea, by wrapping monel wire (it was all I had to hand) around the stud with a view to compressing it onto the stud - clearly this didn't work, the monel wire being too smooth and too hard to compress. I will give it a go with some other shim.

So, lets presume these Irwin extractors don't work - I'll seek advice from Kent Marine Services to see what they suggest - I can only think they will advise taking the head off. So that would involve:

Taken from page 105 of here: http://www.albinballad.co.uk/wp-content/uploads/2013/04/YanmarGMHMWorkshopManual.pdf. It doesn't look like rocket science if it comes to this nuclear option... I will get a quote from the chaps at KMS though... although I do love learning this stuff and doing it for myself as it all adds to my understanding of the engine, which is a benefit when at sea.

 

[ghostlymoron]

What length of stud is showing? I had about 5-6mm showing on mine after removing the flange and it came out easily using 8" stillsons. Stillsons much better than Mole grips as they tighten the more force you use.
I decided to try the cheap option first before buying expensive special tools and was glad I did.
Taking the head off is not difficult but you'll have to replace the head gasket which is expensive.

 

[RichardS]

As Richard says Bikedaft, as I can only get access to the stud from the side, I wouldn't be confident drilling the little sucker out without taking the head off. The compression is awesome on the engine, so I am very reluctant to take the head off apart from as a very last resort.

I used the blue tack well idea (thanks chaps) and left it for a few hours (I have left the well in place now too so it can soak for a week).

Richard, yes, it works exactly like a drill chuck and the jaws of the smaller one are too far inside when working at its upper limits.

I did try something like your shim idea, by wrapping monel wire (it was all I had to hand) around the stud with a view to compressing it onto the stud - clearly this didn't work, the monel wire being too smooth and too hard to compress. I will give it a go with some other shim.

So, lets presume these Irwin extractors don't work - I'll seek advice from Kent Marine Services to see what they suggest - I can only think they will advise taking the head off. So that would involve:

Taken from page 105 of here. It doesn't look like rocket science if it comes to this nuclear option... I will get a quote from the chaps at KMS though... although I do love learning this stuff and doing it for myself as it all adds to my understanding of the engine, which is a benefit when at sea.

Yes, the monel wire is the same concept but you need something rough. Using a "vertical" shim rather than a radial one might allow the extractor jaws to grip the stud at least on one side.

but, if that doesn't work, here's another idea which might be better than head removal. This is the kind of thing I've done many times but it's rather a one-way street. If the extractor really is like a drill chuck, then you can adjust it to the right size to grip the stud and then hold the extractor against a grinding wheel and grind off the body until the jaws are more or less flush. It will get hot so take care. I use my grinding wheel to "modify" tools every now and then but it always hurts as the tool is then more limited for future use of course. If you don't have a grinding wheel I'm sure any decent garage will do it for you in two minutes as a favour.

Richard

 

[Hydrozoan]

... I used the blue tack well idea (thanks chaps) and left it for a few hours (I have left the well in place now too so it can soak for a week). ...

:encouragement: You seem to be doing a good job of avoiding Pirsig's 'gumption traps' and keeping the level of that important fluid well topped up, too. All the very best!

 

[MagicalArmchair]

The Irwin toys are here!

The trouble is the size is either 3/16 inch (4.8mm doh, probably slightly too small) or 1/4 inch (6.4mm way too big then). I am counting on being able to hammer the 3/16ths grip onto the stud - at least it will be a snug fit (if I can get the sucker on there). Else, Richard, indeed, I'll augment the laser tool - although at the rate I'm going, if the Irwin tool doesn't work, I might have worn enough off the stud to make that latch on...

I awaiting a response from the engineers too, their first response was doubtful they would be able to get it off with the head in place but they would be happy to have a go .

 

[ghostlymoron]

Mark, I've looked at your pics again on my laptop this time and, in my opinion, you've got plenty of stud showing to remove it with Stillsons, provided you've got room sideways to swing them with a tube over them. As I've said elsewhere, Molegrips won't work as they don't tighten up as you apply force.

 

[MagicalArmchair]

Mark, I've looked at your pics again on my laptop this time and, in my opinion, you've got plenty of stud showing to remove it with Stillsons, provided you've got room sideways to swing them with a tube over them. As I've said elsewhere, Molegrips won't work as they don't tighten up as you apply force.

One notable gap in my arsenal is Stillsons Sevenoaks (where my office is) has a cracking hardware shop, I'll go and grab one on lunch as a plan B! Thanks Ghostly, hopefully this weekend I'll get the blighter off one way or another... (depths of despair last weekend when the 1mm-6mm extract didn't come up trumps )

 

[ghostlymoron]

For that particular application, I should get a modest 8" or maybe 10" if there's room for it. I used to have a USA made one that I got at our local antique centre. Unfortunately, it must have fallen overboard so I'm on the look out for another one.

 

[ghostlymoron]

At least there are other uses for Stillies.

 

[MagicalArmchair]

At least there are other uses for Stillies.

Roger that, I'll sort myself out with some, it'll give me something else to wail on that studding with if the extractors fail. Thanks Ghostly,

 

[vyv_cox]

I've lost track of this saga somewhat. When you posted about 'the extractor' was that the Teng type? I see that you felt it was rounding the stud too much, so that it would no longer grip. Have you tried wrapping a bit of sheet steel either all or partly around it? It will still grip well using this method.

 

[MagicalArmchair]

I've lost track of this saga somewhat. When you posted about 'the extractor' was that the Teng type? I see that you felt it was rounding the stud too much, so that it would no longer grip. Have you tried wrapping a bit of sheet steel either all or partly around it? It will still grip well using this method.

Saga is the right word - yup, I am at the Tengs lower operating diameter of <5.5mm of the stud (which is going some considering its an M8 bolt). I did try wrapping some monel wire around the stud to get purchase with the other tool, however that made little difference. Richard came up with the suggestion of shimming it with a nail next to the stud, so will try that too. :nonchalance:

 

[MagicalArmchair]

Finally, after a rather bleak conversation with a mechanic who said the head would probably have to come off, the bolt is out!!! I went down armed with the bolt extractor and a shim made from a chopped up nail, some Stillsons that I found in my late fathers stocks and the Irwin extractors.

I thought I'd try these first and offered the the 1/4" up to the stud and it was a tight fit closer to the head (which is odd as 1/4" converts to 6.35mm... which should have been do-able with the stud extractor?). I had to hammer it on mind you, which had the effect of shocking the stud and driving the extractor hard onto the stud.

I loaded it up with torque very slowly and gently - until the end of the Irwin extractor sheered off ! I moved my socket up the extractor, and continued. With a crack, it started to come! Note the threads look dry, meaning the Plusgas never managed to penetrate the threads - perhaps I didn't add enough heat to it?

You can see how deeply the extractor cut to get a hold on the stud - talk about touch and go. And Ghostly, the Stillies did come it handy anyway for removing the stud from the extractor!!

Thus ends the saga.... phew :encouragement:

 

[bikedaft]

Finally, after a rather bleak conversation with a mechanic who said the head would probably have to come off, the bolt is out!!! I went down armed with the bolt extractor and a shim made from a chopped up nail, some Stillsons that I found in my late fathers stocks and the Irwin extractors.

I thought I'd try these first and offered the the 1/4" up to the stud and it was a tight fit closer to the head (which is odd as 1/4" converts to 6.35mm... which should have been do-able with the stud extractor?). I had to hammer it on mind you, which had the effect of shocking the stud and driving the extractor hard onto the stud.

I loaded it up with torque very slowly and gently - until the end of the Irwin extractor sheered off ! I moved my socket up the extractor, and continued. With a crack, it started to come! Note the threads look dry, meaning the Plusgas never managed to penetrate the threads - perhaps I didn't add enough heat to it?

You can see how deeply the extractor cut to get a hold on the stud - talk about touch and go. And Ghostly, the Stillies did come it handy anyway for removing the stud from the extractor!!

Thus ends the saga.... phew :encouragement:

well done

 

[ghostlymoron]

I was wondering how you were getting on with it. Well done.

 

[RichardS]

Brilliant. I'm delighted for you. And although it must have cost quite a bit I would still rather go through all that then break a perfectly sound head gasket.

Just don't forget to smear plenty of copper grease on the outer end of the stud before you put the nut on and you, or a future owner, will never have to go through that again!

Richard

 

[bikedaft]

Just don't forget to smear plenty of copper grease on the outer end of the stud before you put the nut on and you, or a future owner, will never have to go through that again!

Richard

I was wondering whether to mention that or not..

i do it, but not sure if you are supposed to? another dissimilar metal. works a treat on car wheel bolts tho

but lubricant on the thread can lead to over torqueing even with a torque wrench so watch that...

 

[RichardS]

I was wondering whether to mention that or not..

i do it, but not sure if you are supposed to? another dissimilar metal. works a treat on car wheel bolts tho

but lubricant on the thread can lead to over torqueing even with a torque wrench so watch that...

On that issue I just ignore what manufacturers say. Every single nut, bolt and stud on all my bikes and cars are plastered with copper grease, and that includes wheel studs and brake caliper bolts which are not supposed to be greased. I would also copper grease the manifold end of the stud but I didn't suggest that as you need to know how to use a locknut to tighten it. I can strip any part of any of my vehicles down without any of the stress suffered by Mark.

I only ever use my torque wrenches for bearing cap bolts. All others I do up as tight as is necessary, which is nearly always about 25% less than the manufacturer recommends, and about 50% of the torque in the case of wheel nuts. And no, after 45 years I've never had a nut fall off!

Richard