[RNByrd3]

Hi all,
I am the owner of a 2006 330i. I went to do a routine oil change and found that the oil plug just keeps turning and turning. From looking at this forum, it seems this is not an uncommon occurrence. The problem I'm having is what the mechanic at a local import shop is telling me. He is telling me that the pan itself is not threaded and that there is a "bolt" inside the pan that the plug threads into, and this is what broke away causing the plug to keep turning.
I was under the impression that the pan was threaded and the plug simply threads into this. Can someone confirm or deny what the mechanic is telling me is accurate? If it's just the threads on the plug, I have a new plug to replace it. If it's the threads on the pan, I was told that this can potentially be repaired with a heli-coil insert. I'm just trying to avoid a $1,200 bill if possible.
Thanks in advance.

[BKV122]

To my understanding and experience the pan is Female threaded and the plug is male threaded.

But from what your mechanic is saying it would seem to make more sense if there is a "nut" and the plug, acting like a bolt, would thread into the nut. This "Bolt" inside the pan theory makes no sense.

Now, what are you trying to do remove or reinstall the plug?

[Efthreeoh]

Either your mechanic is stupid, or he didn't explain it well, or you misunderstood him. Have the same engine as your car and I've DIY'd the oil pan gasket. You don't say whether your car is a manual or automatic, but it makes a difference because the automatic trans version of the N52 (engine designation) uses an aluminum oil pan. The manual trans version uses a steel oil pan. The steel oil pan is painted black.

That said, there is no "bolt" in the oil pan that the drain bolt threads into. On either version of the oil pan, the material of the pan (the casting for the aluminum pan, or the stamping of the steel pan) is thick enough to be threaded (similar to a nut). There is no "nut" built into the oil pan, it is just the hole is threaded (as you suspected).

Before you go to the extent of replacing the oil pan, I would get the next largest size oil pan drain bolt and ream out the oil drain hole in the oil pan and re-tap the hole to the next larger sized oil drain bolt. The original equipment drain bolt is a M12x1.5 (1.5 is the metric tread pitch - M12 means the bolt is 12MM in diameter). The next size up would be a M14x1.5 drain bolt. You can go several ways with this procedure (1) ream the hole and re-tap using a M14x1.5 threading tap, or use a self-tapping oil drain bolt. Below are two links to such products.

https://www.oreillyauto.com/detail/d...090197/4177528

https://www.lawsonproducts.com/lawso...lug/KT11804.lp


If it were my car I'd ream the hole and re-tap a clean set of threads using a threading tap, but I own such tools and know how to use them. A good auto mechanic should know how to re-tap for an over-sized drain hole.

All that said, if your oil pan gasket is leaking, you may just want to replace the pan anyway (they are not cheap... $400) while the oil pan gasket is being replaced. Or re-tap the oil drain hole with the pan out of the car to an M14.

Good luck with it.

[David0ff]

I had this problem and its a pain in the ass to pull it out if its stripped.
This magically happened after the last time I took it to BMW for a pre end of warranty inspection + oil change.

When I did the following oil change, SURPRISE!!! stripped and turning.

You have to pry it with something while turning it or pull on it with a vice while turning it or a combination. After several hours of fuking with it, it will come out. At the coming out point you may not want to be directly under it.

Then you visit an auto parts store and get a plug + tap kit and remake the threads.

Total out of pocket will be around 10$ American but you will swear lots for several hours.

Good luck

[AngelFarelli]

Originally Posted by Efthreeoh

There is no "nut" built into the oil pan, it is just the hole is threaded (as you suspected).

That would be genius if there was a nut on the inside you could replace instead of the entire pan. :