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Discussion Starter #1
Follow up to the below thread..........

http://www.m5board.com/vbulletin/e3...valve-covers-removed-lots-pics-long-text.html

Here's how I Re-Coiled the stripped cylinder head holes..........

Tools required for the job........
The custom tap for the re-coil states a 6.2mm drill is required, I went with a 6mm drill as the cylinder head is made from cheese figured it would be OK.



I chose the longer of the 2 coils, pictures show coils and located on collar bolt.......





The 6mm drill would nearly fit in the existing stripped hole so figured it would not be removing much material. I measured the depth of the hole at about 20mm and put a marker on the drill at 18mm so I would know when near the bottom of the hole.







Prepared the paitent for surgery, don't forget to cover your alternator as well.........





Put a bit of WD on the drill and in the hole, lined the drill up, critical part this, and gently operated the drill, as the alloy is soft the drill will want to snatch at it so you got to be careful here, small incremental rotations, plenty of lube!! As figured not much material left in the hole....





Cleaned the hole out with cotton buds and vacuum........



Aligned the tap, took some time over the this, setting it correctly on the first few threads is important. Took that long to set it up the sun had come out.......



I then started to cut the new thread, really took my time here, half turn forward, quarter turn back, removed the tap after 4 or so threads to clean up tap and hole and re-apply lube.........continued to do this until tap was fully inserted into hole.........





Removed tap, rinsed and repeated for other 2 holes, new threads looked good nice shine on them, no snags anywhere, tried to capture new thread.....



Coil on the insertion tool..........



Although I started the coil by hand to ensure it was seating correctly in the new thread.......



Drove coil until the top most thread was below seal surface on the cylinder head......









Snapped off the drive tag on the coil and vacuumed it out of the hole......



Cleaned up the new coiled holes..........



Inserted the collar bolt, threads felt great, nice and tight but no resistance whilst tightening down.............




Thats it, took me 2hours to sort all 3 holes out, it went that well I was tempted to do the other head but after inspecting the threads they seem OK so left them alone. I was ultra careful on every operation, after all its the cylinder head, not like if I mess this up just order another one.........Drei Bond 1209, new collar bolts and sealing washers turned up yesterday, plan to put the covers back on next week.....


Mike
 

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Thanks for the write up,mate!

BTW,it is the upper chain cover where you re-coiled the threads.

So even if messed up,it is not so hard to replace.Just Vanos unit and a few other bits removed and changed...
 

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Discussion Starter #3
Gotcha........even so, presusre was on.........
 

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Very good writeup and pictures. Excellent work.
 

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Discussion Starter #8
yeah I had heard that Ger and was arguing with some fella in work who was stating that its just the same, I will now show him your reply..........nice one........
 

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Helicoils to the rescue again! Nice work.
 

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Nicely done! Great pictures and write-up, thanks!
 

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Great writeup, very clear. And nice job on the coil as well.
 

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Discussion Starter #14

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Thanks for the write up. That is almost exactly how I did it, but I did not use a drill, I Just used a drill bit with the tap tool to turn it. I was to scared to screw up with a drill.
 
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Discussion Starter #17
yeah I know what you mean about the drill, fortunately the drill speed is realted to trigger squeeze, still was scared of screwing it up........

and yes thats my garage 'M' PC with the F10 as desktop background.............
 

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yeah I know what you mean about the drill, fortunately the drill speed is realted to trigger squeeze, still was scared of screwing it up........

and yes thats my garage 'M' PC with the F10 as desktop background.............

HAHA, saw that as I looked at it again, it looked like it was a reflection off your car HAHA!
 

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Respect...

Nice job.
 
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