Quote:
Originally Posted by electricbrew
I just helicoiled mine a few weeks ago. I agree that you don't need a vacuum or anything like that. I just used grease on the drill bit and went very slowly and cleaned out the drill bit often. The metal shavings want to walk down the drill bit, not up into the oil pan. My advice is that if there's any way that you can do this on a lift, it will be A LOT easier to keep the drill bit straight than doing it on your back with the car at an angle on jack stands. It's important to keep the drill very straight because otherwise your mating surface between the bolt and pan won't be completely flat. I'm not sure what the right torque for a helicoil would be, but for me it seemed like the stock 18nm was not enough. It was leaking enough to have a frequent drip. I slowly tightened it an umph more (not sure on the umph to nm conversion) and it still felt solid and the drip slowed significantly. I wasn't able to eliminate it fully, but that could be for a number of reasons. I didn't have a new drain bolt and didn't want to leave the oil out of my car for long enough to get one and I might have scored the mating surface while trying to get the old bolt out, which was seriously challenging in my case. I also used a crap copper washer and might have been better off using a rubber or other gasket. Anyway, the bolt is holding in the helicoil and i was viewing this as a temporary fix until I can get it to bmw for their permanent fix that fits the M14 bolt.
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Ok first off there's a few things I noticed that I would like to address:
1) torque spec is 25 NM not 18nm.
2) you need to use a brand new copper crush washer. If you reuse an old one it won't be able to crush down any further and seal properly. You will also risk stripping the threads again if you keep sinching the bolt tighter to stop the leak. This is a major cause of stripped bolts in the first place - reusing washers or using crap washers.
3) you should replace the old bolt, the threads on that could be damaged from stripping the pan - unlikely because it's steel and much stronger than the aluminum pan. But it's possible.
4) a helicoil is technically a permanent fix, not a temporary one. Especially if you do it right.
I personally don't like the idea of tapping up to m14 because you'll be removing a lot of material from an already thin side wall. Also the side wall has a notch in it making it even weaker.