Just repeating this suggestion from my original posting...once you got the right (left-H) drill bit sorted out, this will be a very helpful tool(s). You can get them from numerous US sources, and the really are extremely high quality tool.

https://www.rennsteig.com/en/product...l/4719043.html

 

Steve, now you're on the right track! I would start with smaller size drill. Here is the thought:

• Take M6 bolt.
• Take a 2mm drill and drill hole through center of the bolt.
• Cut head ot he bolt off, so the length of the remaining body is close to thickness of WP flange.
• Now you have yourself an imporovised drill bushing good enough to drill 2mm pilot hole in your broken screw.

Here is how math works out: M6 bolt has solid body about 6mm, typical close clearance hole is about 6.4mm normal fit is 6.6 loose fit 6.8. So, at worse you're going to have +/-0.4mm endplay on diameter. Drills up to M4 will guarantee not to damage threads!
Now you can use this drill busing will guide your drill bit.
Small size but will be much easier to put a pilot hole, than trying to drill M5 hole from getgo.
You can open pilot hole to something like 3-4mm not larger in a second go at it.
Now you can use a square bolt extractor.
If you manage to drill hole all the way through the bolt, squart plent of penetrating oil inside, all the way inside! let it sit over some time, like overnite.
Heat is your friend! thermal expanson of aluminum is 0.000023/degreeC; steel is about 0.000012/degreeC so for every 10C T rise there is 0.7micron clearance for 6mm bolt. For 100C T rise it will be 7 micron clearance. Too bad it is all filled with gunk!
Good Luck!
BTW that welder, that refused to weld, he is a good man. I knew in my time plenty would take the job, charge arm and leg for it and run away after got paid and damage is done!

 

Thanks Chris & Big Koshka,

Can drilling the 2mm hole down the center of the length of the bolt be done without a drill press. I've been wanting to get one for awhile, maybe this is the time?

 

So, once I use the bushing to make the 2mm hole through the bolt to be extracted, since the Rennsteig tool #1 for extracting a 5mm bolt requires a hole 3.2 – 4.8 mm, I would drill the bolt with a 4mm bit using the 2mm hole as the guide. Before drilling the 4mm hole, I could remove the water pump and let the 2mm be the pilot hole & I would not need any kind of bushing either? & the only reason for using a LH thread would be in case the force from the drilling should be enough to start the extraction?

Thanks and best,

Steve S.

 

You've got it!
Just try to avoid these:
https://locostbuilders.co.uk/upload/a841252-4bolts.jpg

 

After using a drill bushing made with a 1/8" bit from a bolt, I tried each of the above. The extractors in a group of three have a "collar" which precludes them from burrowing below the mounting surface; it is too large. The spear-like one also would require burowing into the mounting surface; the steel bolt just powdered at the first go. The third one could have worked, but didn't. If I had to do again, I would have drilled and tapped to begin with. PAINLESS & FLAWLESS!!
Also, I was able to find a pack of 10.9 strength identical bolts for under $10.00. New water pump is all primed and ready to go. Since I have also gotten the cam covers back on, I'm ready to start the reassembly.

 

Hi Steve,

congratulations to a job well done! It is always such a rewading feeling when things finally turn out well!

Best regards,

Thomas

 

Amen, brother!!