Drilling out a hardened steel 'roll pin'

[brucemillar]

Friends

My Pajero decided that now is a good time for the Crankshaft Pulley to part company with the Crankshaft. The Pulley is held on by a large bolt (new bolt & pulley on order). The pulley locates onto a 'Steel Roll Pin'. As is common the roll pin has snapped in the actual crank end (life is just not fair).

Now the good news. The broken end of the roll pin is visible and will be able to be drilled out. I have tried an 'easyout' but there is just not enough meat for it to bite into.

Back to the question:

What is the best possible drill bit in a 5mm / 6mm size that I can get to drill this out?

I will probably only get one shot at this and if I fail, then it is not good news for the truck, as it will inevitably be a write-off. I am not going to remove the crankshaft.

So a best quality drill bit for a hardened steel 5 or 6mm roll pin please and where can I get them?

 

[gaz_l]

If the pin is hardened you'l be wasting your time using an HSS drill bit, you'll need to use a carbide one. These are available from your friendly local engineering suppliers, although they're not cheap.

The bad news is, although carbide is very hard it's also brittle, and carbide drills don't take kindly to off-axis loads. Unless you're very careful when using a hand drill, you can quite easily end up with a broken drill bit, and you'll be worse off than when you started.

I don't know how big the journal on the crankshaft is, but if you can get away with using a stub drill (DIN 6539) you'll be in with a better chance as a stub drill will be more rigid than a jobber.

Good luck!

Gaz

 

[brucemillar]

Gaz

Excellent reply. Thank you. We do not have much space as the engine is in situ, with the viscose, etc removed. The plan is to use a 90 degree chuck. The broken end of the pin is about 0.25". I think that providing we can get the drill bit into the end of the broken pin? We will be home & dry, as it is not quiet flush with the crank sprocket.

Drilling is only one option. I am happy to consider other ideas to get it out but suspect that I may have only the one chance, so do not want to knacker it.

 

[KennyN]

You can get drills that will drill out taps and eazy-outs , they dont look like conventional drills and i used them last week to remove a broken tap that was wedged into a pushbike crank.

http://omegadrill.com/images/4_Omegadrills-L_to_R.jpg

Before you try the above then is it not possible to screw a bolt into the centre of the roll pin and use a slide hammer to draw it out that way.

I managed to break the fancy 6mm drill i was using so i ordered another half dozen before i went off shift last week , if they have arrived then i can send you down one tomorrow morning as i am on nights tonight.

Kenny

 

[WOODYTHEWISE]

This forum, and the people in it are 1st class. How helpful is the above....

 

[brucemillar]

You can get drills that will drill out taps and eazy-outs , they dont look like conventional drills and i used them last week to remove a broken tap that was wedged into a pushbike crank.

http://omegadrill.com/images/4_Omegadrills-L_to_R.jpg

Before you try the above then is it not possible to screw a bolt into the centre of the roll pin and use a slide hammer to draw it out that way.

I managed to break the fancy 6mm drill i was using so i ordered another half dozen before i went off shift last week , if they have arrived then i can send you down one tomorrow morning as i am on nights tonight.

Kenny

Kenny

Like Gaz, what a fantastic reply.

So this is where we are at: With a standard 18v Makita cordless drill and a 90 degree swivel chuck, I have just enough room to get onto the end of the broken roll pin. We are working in the gap between engine block front and Radiator. Space is cozy.

There is not enough room to tap the pin through and I would worry where the broken end would end up?

It will not allow enough room for a slide hammer - But I like your thinking. It will take an "easyout" but that feels like it may damage the remains of the pin, to the point where I lose the chance of drilling it out?

My preferred route (given the above) will be to drill it. Your drill bits look excellent and I will happily take you up on your offer. I shall PM you may details.

I am feeling somewhat lucky here right now. As I had been told that it was a woodruff key and hat the crank nose would be damaged. To find a broken pin with an end still visible is indeed good luck (if you get my gist). It does look like the Crank Bolt stretched allowing the pulley to flutter and break the pin. The pulley has been well ground with a large pile of filings lying on the bash plates. No other damage is visible.

On the Pajero site. Some say drill out a big hole in the Crank Plate (roll pin hole) and the pulley hole then fit a larger diameter steel pin. For now I will stick with Stock unless the drilling creates a bigger hole.

My plan is to Loctite the new Crank Bolt and correctly Torque it using a homemade pulley tool to jam the engine. That should outlast me. It is such a great little truck, it is worth the fight.

 

[Ted]

I can't quite envisage what you have there, Bruce, but the way we used to get woodruff keys out was to grip them with a pair of cutters and use the leverage of the cutters to pull it out.
I know the roll pin is hardened rather than a soft woodruff key, and you will need something left to grab onto, but it may be a thought.

Or I might just be talking bollox

 

[Trickythemerc]

Bruce
If the roll pin is hollow, you could try running a tap into it and use a bolt with a combination of nuts, washers, wife's knicker elastic or anything else you may think of to wind the roll pin out. I once extracted a steel bush out of a blind drilling using the aforementioned bits of kit. At least with a bolt down it you have something to work with.

 

[optimusprime]

Yes good idea tricky Good luck bruce .Wish i could help you more ..

 

[brucemillar]

Well. Thank you all so much for the great replies and really practical help. Kenny has offered a drill bit and I have accepted. I am stopped new as I have to await the new parts to arrive on Friday.

I will replace the:

Crank Pulley / Harmonic Balancer
Crank Pulley Bolt
Roll PIn
Idlers and belts.

One of the idlers is a 'six week' special order from Japan with zero showing in the UK. I use Agrimec Pajero, who just around the corner from me and are great for sourcing obscure Pajero parts. They have drawn a blank on this. But do have another V6 for breaking with what they believe is a newer idler than my 'grumbling' one. I will go with their one as I can't really wait another six weeks for an idler. If it is noisy, It is easily replaced.

Realistically it will be next week now before we get any real progress. I shall update then. Many thanks to all who read and took time to jump in with help.

One thing else: Has anybody any experience of locking the crankshaft pulley, while torquing up the bolt? Some say that you can wedge a breaker bar against the chassis and flick the ignition. Others say use a chain wrench or make up a tool. Making up a tool is probably out as I have no welding gear. I do have wrenches and breaker bars and loads of hammers!!

 

[Smart320]

As usual Bruce your threads have plenty of content to keep me enthralled! Cannot wait to read the next instalment, or should I say un- instalment!

 

[optimusprime]

Tricky above as it bruce Try and thread the roll pin first . Then use a bolt the same as the thread you have put inside the roll pin , screw it right inside the roll pin and with washers larger than the roll pin and a nut , lock it up , till it pulls out. Just looking at the Mitsubishi web site that the pojero is on with the same problem. But he was lucky the engine was out on the back yard ..

 

[Druk]

Proper crank locking tools usually involve removing the starter motor and bolting a special plate across the hole which has teeth which engage with the ring gear. A lever/pinch jammed in the tooth nearest the bottom of the starter hole works pretty good.

Edit. Found this on Google.

The Mitsubishi Pajero Owners Club® :: View topic - Tightening Crankshaft Bolt



.

 

[optimusprime]

Dont think an easyout will be of use .The roll pin hole will have no thread inside it You must thread it it first .The easyout needs a thread to withdraw the roll pin , or bolts that are broken inside a blind hole like this one .

 

[brucemillar]

Proper crank locking tools usually involve removing the starter motor and bolting a special plate across the hole which has teeth which engage with the ring gear. A lever/pinch jammed in the tooth nearest the bottom of the starter hole works pretty good.

Edit. Found this on Google.

The Mitsubishi Pajero Owners Club® :: View topic - Tightening Crankshaft Bolt



.

Derek

Saw that. Thank you. I am a member on there. You will note that there is no definitive answer. Rather a "this works for me" as is often the case. As my bolt clearly came loose, I want to avoid a repeat. There are holes in the Crank Pulley for a tool to be used. We may just try and get something onto them or lock it via the flywheel if we can get access.

 

[Stratman]

Is it possible to drill a hole through the crank nose diametrically opposite the pin, then use a punch to knock it out from behind?

 

[GordonTarling]

If the crank nose is drilled all the way through, could you not tap the pin through just a little way and that might give you enough to be able to get a grip on. If you can't get a hammer and pin punch in there, try using a short bolt that's slightly smaller diameter than the pin and 'squeezing' it through with the aid of a G clamp or something like water pump pliers.

 

[brucemillar]

Gents thank you. Not easy to explain here. But with the Pulley off and looking directly at the crank nose! All you have is a flat metal six inch non removable disc, with the roll pin end, pointing out towards you. You cannot get behind the pin/plate without stripping down the timing case and that is a big job on these beasties. Lkewise to punch the pin straight through is not on, as the hole does not extend all the way through the plate.

So it is:

Pull it out - not enough pin to get a grip on.
Drill it out - Favourite at the moment.
Tap and extract with bolts etc - It is a very small pin and I think it will shatter or make things worse.

Now. We could just grind off the remaining pin and drill and fit a new one. But space is really tight and we are probably spending a tenner to save a fiver ;^)

On the Pajero forums this does appear to be a fairly common failure - AFTER - people have removed the pulley for whatever reason. The bolt stretches!! It requires 180+Nm on a new bolt, so is a beast.

Most have succeeded in drilling out with some leaving an oversized hole and using an oversized steel pin. It is primarily a locating pin. Any torque should be absorbed by the bolt being correctly torqued . That is the theory. We could go all out for true bodge. Grind the old pin and araldite the new pulley & Loctite the new bolt. Fun to do, no so much fun to undo. But it may well outlast me ;^)

Nope. I want to go down the drill route with a new bolt and Loctite.

 

[optimusprime]

We are all with you Bruce .

 

[pmcgsmurf]

Very interesting, I do like reading your posts Bruce, keep us informed.