SOS, SNAPPED HEADBOLT

[MillesimeEnjoyer]

Hello, i am in a bit of a pickle.

So, i was changing my headgasket because the old one desintegrated. And whilst i was loosening the headbolts 1 became suspiciously hard to remove, so with a terrible gut feeling i applied more pressure. Then a loud bang and the bolt jumped out of the block, with the thread still inside.

Now, i made an attempt at drilling it out but the drill keeps wandering to the side.

My solution: turn a guide bushing of 14 mm (size of hole in block) with an inner diameter of 10mm (diameter of the core of the bolt) for the drill to go through. This will hopefully make the drill drill straight and thus drill out the bolt.

The engine is the 1.6 litre BDY 8 valve from a 1992 BX


Are there ANY other ways to do this, welding a nut is not possible since the thread starts approx 40mm deep from the top of the block.

Thanks in advance!


(Its always the last bolt that goes )

[thorter]

Spark erosion is effective, if slow. Unfortunately, though possible, it is a lot of work to rig up a means to do it yourself for this sort of case. You could check if anyone offers such a service.

[thorter]

Another comment. If trying to remove the broken threaded section by drilling, I would suggest starting with a small drill (say 4mm, and buy a good quality make like Dormer), and make a close fitting guide bush to centre things in the bore. It must contact the broken bit and locate on the diameter there. Once you have a well centred 4mm hole, it is relatively easy to enlarge it in stages. Do be careful though - a broken drill in the block would convert a difficult situation into a disaster.

[panky]

Yes go up in steps with the drills and use a centre drill to start things off if possible.

[thorter]

I wouldn’t use a Slocombe centre drill. While it provides the best centring, it is all too easy for the pip to break off, leaving it embedded. A spotting drill would be best, but the 40mm depth suggest it will take an ordinary drill to reach in far enough.

[MillesimeEnjoyer]

Hello, i have good news.

Drilled out the broken bolt and rethreaded the thread.

engine seems fine and working better then before!

[panky]

Thank goodness and well done