Taps and “ez outs” are so brittle that I’ve learned (the hard way) to not even consider using them in situations like you are facing . It takes a very educated hand to know how much pressure to use on a tap or ez out. Getting the educated hand is a painful process.

Drilling is slow, but safer.

In the OP’s shoes I’d be buying the best magnetic induction tool I could afford. As previously mentioned, they seem like the best way to proceed.

Z

 

I just wanted to confirm that your crank is induction hardened and tempered but only on the bearing journal surfaces (4xPins and 5xMains) to 1mm depth. The rest of the crank is untreated base material for higher strength. The area that you are working on is called 'the Post End' and this is definitely NOT hardened.

 

I've been following this thread with interest and horror, as I have removed and replaced my harmonic balancer a couple of times with dread on every turn of the wrench.

Were I in this position:

The magnetic induction cure sounds promising.

Turning the project over to a machine shop - possibly with magnetic induction capability - would likely be my go to as anything more complex than a heli-coil is out of my skill set.

And, I have a suggestion that involves thinking out of the box (my box anyway) but may have some merit...If the end of the crank is not hardened, as PKWise suggests, would it be possible to weld a threaded stud to the end of the crankshaft and attach the harmonic balancer with a big nut and washer. Hopefully, I'm not a big nut, but why not? If this is possible, it's still a project that I would turn over to a machine shop, but would seem to be a relatively straightforward job for a shop with the right tools and skill.

Hopefully this helps or at least provides some amusement.

Happy New Year and wishing everyone much success in 2022 !

 

The bolt turned and came out nearly all the way, I think there is about 1/2 of the bolt stuck inside. Will try again this weekend with the suggested small blow torch flame. many thanks

 

I think there is about 1/2 inch of the bolt left flush with the crank?

 

Thank you so much!!
Does that mean that I can try to drill out the bolt and if the original threads get damaged I can still re tap the end of the crank and fit a new bolt????

 

I looked at induction heating but cannot see how you would be able to get the conduction coil around the bolt which is broken off at the end of the crank?
Also our idea of drilling a hole say 3/8 into the broken bolt and securing the harmonic balancer that way would this work?
Would a 3/8 holding on to 1/2 thread in the crank be enough to hold ?? or would the torque from the engine take out the 3/8 bolt??

 

I was hoping to sell the car after fitting a new front seal and I am nervous about passing the car onto someone if the job when completed is not safe?? Thoughts??

 

I am looking for the bolt size the invoice only gives me 1 AJ89909 Bolt I have looked all over the internet but cannot find the size details, the bolt head says CM 10.9 is this a metric bolt and thread?
If so what size drill and tap would I need for this bolt?

 

​​​​​Super interested... Can you say a little bit more about how this would work in this situation?

 

The balancer needs to end up on a certain plain that considers the ride of the serpentine belt and all the other pulley wheels. Welding a bolt to the end of the crank, or working things in a way that would leave the balancer out of it's original position might create some problems...

 

oldmots should answer that, as he has more experience with them that I do.

Z

 

I believe so, yes... But, the remaining 1/2 of bolt material has to come out of that hole. That's the only thing I can see working for a permanent solution... Brotha, I don't envy your situation here. Keep at it, you'll get it - or not 😖

I really think that if y'all can go to the hardware store and find several very short sections of copper tubing that slide inside one another,,, for a CENTER section that will land on that bolt head,,, and y'all can start pooling some steel on that bolt head,,, the heat of the welding, burning that GD stupid thread locker, to a point where you can weld a short bolt head to the new steel MIGHT allow ya to back it out the rest of the way.

 

When I worked for 2 consecutive printing press manufacturers we would clean and prep many machined parts for assembly. Chasing threads ("taping" holes already threaded) an oops would happen sometimes. The machine shop department had an EDM thing (not sure what that stood for) that burned out the broken tap/drill/bolt without damaging the original threads. Must have been magic!!
So assuming that is the same as the induction thing mentioned above I wouldn't go any other way. Welding something to the crank is not a safe proposition. And if you use a 3/8 bolt (if you can get the tap remains out) then you are only threading into the remains of the original bolt, not strong enough. You have to get that out of there and clean up the threads in the crank.
I found lefthand metric taps on line in the event it is left-handed. Glad I'm not in you shoes but it can be fixed. TM

 

I've been watching this with horror as well as I am going to replace my Uncle's XK8 timing chains/tensioners. Was that crank bolt original? Do you know if it ever was removed and replaced?

I know in the FSM it states to never re-use one but I wonder how many mechanics at other shops just put it back in? So scary.

 

If you re-use the bolt, just use some 'tread-lock' compound to duplicate the factory prepped bolt.

If the bolt starts 'galling' on the way out, STOP and use penetrating oil and move the bolt in and out like you would a tap.
Heat might also help loosen the thread lock compound?

 

I was under the impression you were NEVER supposed to re-use the bolt due to the insane torque specs and the stress of the bolt?

I ordered two OEM ones from Jag as I didn't trust any other manufacturers to get the stress characteristics of that bolt correct. $20 vs a nightmare.

 

Induction tools come with a variety of probes. One of them just looks like a rod. You touch this against the broken bolt, fire it up and wait for it to vaporize what ever is stuck in there. It will burn out taps and other hardened things that get shoved in there trying to remove the broken part. As far as I know this is the only practical method of removing this piece. Drilling out a broken tap is as hard as it gets, I have never had success doing it.

 

I meant to add, induction tools will also work on cast iron. Whenever I had a head bolt broken off in the block, I could take the tool and press it against the block and it would heat the block around the bolt to red hot and the bolt would come out easily. This would only take seconds. These tool do seem like magic. Be careful though, a good one is expensive, best to find a shop that has one.

 

this is why I’m loathe to use ez-outs (essentially a LH tap) and taps in general on broken bolts. Those types of tools are both very hard and very brittle.

The drill bits that can drill out a tap are just as brittle, maybe more so. I was warned not to drop one of these bits because they will shatter.

You might try this product :


https://www.wiseautotools.com/blog/remove-broken-ez-outs-and-more-rescue-bit/

https://www.wiseautotools.com/brands/Rescue-Bit.html

I haven’t used them but sounds interesting. But overall, the induction tool is hard to argue against.

Z