Console mounting bolt broken in block...yikes!

[ErrorMargin]

Edit: I believe this is an M10 bolt
Edit 2: Success! https://forums.pelicanparts.com/porsche-911-technical-forum/1159041-console-mounting-bolt-broken-block-yikes.html#post12219775

I have the engine out of my 84 Targa and I've just now noticed that one of the console bolts has broken off in the block. See the picture below. I suspect that it has been like this since I purchased the car.

How hard is this going to be to extract?

[Ian Comerford]

This is straightforward as the access is good. If you have the tools you can do it yourself. With a centre punch get a nice central start pint. A pilot drill of say 3mm and once this is done check it is central. If it has veered off slightly you can correct with the next drill, say a 6mm, by leaning it in the right direction for a short while and then levelling up. Drill out to the core diameter which I can’t confirm for you as I don’t know the bolt size? You then need a set of taps for that size. Using a starter tap and wrench very gently start to wind it into the hole. The tap will gradually pick out the remaining threads of the old bolt and you may hear a crack as it breaks the first one which can be a bit disconcerting. Gradually, gently wind the tap in and out of the hole picking out the broken threads as you progress. It’s very satisfying and doable at home. Other methods are available of course.

[mepstein]

We usually weld a nut to the broken bolt and remove.

[Dpmulvan]

Guy is asking for help I doubt he has the tools or can weld for that matter. Take it to any job shop or machine shop they should be able to remove it for next to nothing. Or if a buddy has a welder better yet. Not a big deal.

[wazzz]

ErrorMargin's been able to drop his engine and service it so far. I'm sure he can use Ian's procedure above. Only needs good drill bits and a set of taps.
As for the welding, since nothing is sticking out (bolt sheered flush), I don't think a nut can be welded here.

[911obgyn]

I have used left handed drills to remove broken bolts, you must get the first pilot hole centered and use larger bits. The left handed bit needs to be smaller than the threads and as it drills sometimes the broken bolt will back out. Welding a nut to it will heat up the bolt and release it also.

[mepstein]

Originally Posted by wazzz

ErrorMargin's been able to drop his engine and service it so far. I'm sure he can use Ian's procedure above. Only needs good drill bits and a set of taps.
As for the welding, since nothing is sticking out (bolt sheered flush), I don't think a nut can be welded here.

A decent welder can usually build it up into the nut.

[wildcat077]

You're luckky the access is nice and it's not an exaust bolt that snapped ...
Good comments above !

[speeds5]

I’ve used something like this extractor kit multiple times in similar situations. Works well.

https://www.amazon.com/XEWEA-Extractor-extractors-Multi-spline-Extractors/dp/B08L93G1RG/ref=mp_s_a_1_4?crid=AOJ5SGSQ5O99&dib=eyJ2IjoiMSJ9._EjnFpScpuzw1T_X60zaLBuoS2fnRuvuG bGLMK8gm4PmGRY59leVnLmrNKGA8ALJ9uozhXL-exwxQUUTQcqw8mq5iercMpsD48EEF9Mcdt6ZoS-Z2NUECVqUidnJaKXutLzsWqywD-TqcZzhzAFYsKb-NeqGGDcrxlBJZE4DxBIX9FO-bFnrypc6LGpFpSk5sdgRzZanIwZJkmXC0mg-EQ.JMLOB0PO77PAIFSpAKEagmhFNnDRhw8ps8wD1UQTVGo&dib_tag=se&keywords=extractor+kit&qid=1710788225&sprefix=extractor+kit%2Caps%2C181&sr=8-4

[john walker's workshop]

Yup, those things rock. I'd try that first.

[ErrorMargin]

I'll get a set of extractors and give this a try in a few weeks.

Thanks everyone for the great ideas!

[porsche930dude]

I never use extractors anymore. If they break off you are screwed they cant be drilled. So you are stuck with the welding method and that is 50/50 at best. The drill and tap method works every time. You might end up with slightly buggered threads but that is almost entirely within your control.

[john walker's workshop]

If you know when to quit with an extractor, you won't break one. Those short spiral ones usually work fine, in my 60+ years of fixing stuff. Hammer it in well. If you're going to drill, use a timesert kit, don't try to use a tap to remove remaining threads. JMHO

[Jonny042]

Double check the purpose of that bolt, it might be redundant? The console mounting bolt is the one to the right of it in the picture IIRC.

[john walker's workshop]

3.2 console takes the outer hole, the broken one. Shouldn't be too tight, probably come out with little effort.

[Dr J]

Get a punch, put it close to the edge of the stub tangentially and hit the punch with a hammer so as to induce CCW rotation. If that doesn’t work then you can get more aggressive as suggested above.

[ErrorMargin]

Does anyone know the depth of that bolt hole? How far in can I safely drill?

[john walker's workshop]

Probably about an inch left in there.

[stownsen914]

I'd be doing the extractor first (noting advice above). If that doesn't work out, welding a nut is a perfectly good way, I've done that many times and hasn't failed me yet.

[ErrorMargin]

Originally Posted by john walker's workshop

...Shouldn't be too tight, probably come out with little effort.

John, you were right! The bolt came out easily.

I spent the previous week spaying it with PB Blaster and tapping on it help it penetrate.

I bought some expensive Matco left hand cobalt drill bits (1/8, 3/16 and 1/4), and some Irwin extractors, but the bolt came out easily with the left hand drill bits alone.

I started with the 1/8 drill bit and used a McMaster Carr drill bit guide to help get started square to the bolt. I then stepped up to the 3/16 bit and that did the trick.

Thanks to all for the suggestions and encouragement!



I posted the full extraction video here:

https://www.youtube.com/watch?v=xN6vKYQ9xi4