This is a quick repair DIY for anyone with a stripped oil pan plug. This specific article is to fix the pan threads on a 2007 Z4M but the principle can be applied to many other makes and models of cars out there. I believe a ton of BMWs have aluminum oil pans and over time, along with over tightening the bolts (higher than 25 Nm) the threads will be strained and eventually broken off.
My car has 51k miles on it and 2 weeks ago, as I went underneath the car I noticed how access cover for the oil plug was covered in oil. After I took the cover off, I saw a slow drip from the plug.
As I put the wrench to the plug to take it off, I noticed it was pretty tight. Once the bolt was removed, to my horror, I saw 3-4 threads from the pan still wrapped around the bolt.
Once the oil was drained, the plug could no longer be tightened due to missing threads. So at this point I had a few options: a) Towing the car to dealer/indie and have them put a new pan on probably a $3k+ fix or b) attempt to repair the hole.
A few hours of searching the web uncovered a few things for me. First, this is a fairly common problem and second, there are 2 major players in thread repair market. Helicoil and TimeSert. Both are recommended and debated by a ton of people on forums but personally I went with the TimeSert kit as it is a superbly designed and constructed kit.
The TimeSert kit has 4 cutting/driving tools and 5 inserts (to repair 5 stripped plugs). There is a drill bit, a counter bore, a tap and a driver. Here is a link to the exact kit from
Amazon
Jack the car up in the air with enough clearance for a person to work underneath comfortably. Make sure you are always using jack stands and wheel chocks. Remove the oil pan cover plate (plastic piece) and the oil pan plug.
Please note for the entire portion of the repair I only used a tap handle and avoided power tools. With a proper T shaped tap handle, you are in control and metal shavings will not fly up into your oil pan. I also used a heavy grease on all cutting and driving tools which helped me trap most of the shavings .
First step is to cut existing threads using the drill bit and making the opening nice and smooth. Make sure throughout the repair process, all your bits and drivers are perpendicular to the oil pan surface. Time Sert gives you a guide piece, which is no more than a hollow cylinder. However when you are on your back under the car trying to have things square and aligned, sometimes 2 hands are not enough.
Once you have the hole drilled out, it is time to counter bore it. Use the bit included and apply some grease. The counter bore bit has a stopping feature that only allows you to bore the exact depth required. Keep cutting until you feel no resistance from the pan and shavings stop.
Next step, use the tap and guide and make new threads. Remember to use grease or some driving oil to keep friction to a minimum. The trick to tapping as I discovered is after ¾ to a full turn, go back about ¼ turn. This will break up the shavings. Keep turning until the entire hole is threaded. You will know when you’re done once the resistance from the pan subsides. Take the tap out of the hole and clean up the shavings and grease as much as you can.
One of our last steps is putting in the new insert into the newly threaded hole. Put some grease or driving oil on your insertion bit and screw the insert on it gently. Use some oil resistant threadlock on the outside of the insert (which will be in contact with the pan ONLY. Stick the insert and driver in the hole and slowly start to screw them in. After a few revolutions, you will feel some resistance. Keep turning until your insert is flush with the counter lip you bored. Unscrew your driver bit. Clean up the grease from the insert.
Now that the repair is done, it is time to flush out the system and get any stray shavings that grease didn’t catch.
Screw in the oil pan plug and copper crush washer. Pour in a few quarts of 10W60 into your engine and let the oil sit in for a few minutes. Drain the oil from the oil pan plug. Put the plug (don’t forget the crush washer) back on and tighten to 25NM. Fill the engine with 5.5 quarts of fresh 10W60.