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
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