[d_slice1]

Hi all,
So I must've torqued my oil plug bolt with my strong hand during my last oil change because it now feels like the threads are jacked up. It backs out about 3/4 of a turn very loosely but then immediately gets tight again. I haven't pulled it out further than that because my e90 is the only form of transportation I have at the moment and I don't want to have it with no oil and a stripped out oil pan waiting on parts. (I know I know, torque wrenches save lives and money... blah blah, I know I messed up.) My question is, has anyone experienced this before? I'm wondering if the screw is indeed stronger than the pan or if maybe I can just pull the screw and replace it. I'm looking at 1600 dollars for an indy to replace the pan. Probably half that if I do it myself and buy a used pan, (I'd need to buy a bunch of tools though, INCLUDING a nice torque wrench )

[mweisdorfer]

Originally Posted by d_slice1

Hi all,
So I must've torqued my oil plug bolt with my strong hand during my last oil change because it now feels like the threads are jacked up. It backs out about 3/4 of a turn very loosely but then immediately gets tight again. I haven't pulled it out further than that because my e90 is the only form of transportation I have at the moment and I don't want to have it with no oil and a stripped out oil pan waiting on parts. (I know I know, torque wrenches save lives and money... blah blah, I know I messed up.) My question is, has anyone experienced this before? I'm wondering if the screw is indeed stronger than the pan or if maybe I can just pull the screw and replace it. I'm looking at 1600 dollars for an indy to replace the pan. Probably half that if I do it myself and buy a used pan, (I'd need to buy a bunch of tools though, INCLUDING a nice torque wrench )

Use a tool and die kit to re-cut the threads. Irwin makes a great kit. Then use a new magnet drain plug. Dimple makes the best drain plugs money can buy. Take out the drain plug maybe after a few days. The only thing you should be out is the cost of an oil change, cost of a good/great tool and die kit, and the drain plug.

The only thing you need to figure out is the thread pitch.

[d_slice1]

I'll look into getting a set. I'll be pulling the pan anyway to do the oil pan gasket so I should be able to clean out any shavings. My wonder there would be, is my pan going to hold up to a rethreading without losing all thread strength? I think it's an aluminum pan but I may be mistaken there....

[kkasson]

I think you're lucky - if I remember correctly 2006s still had a steel oil pan while later years used aluminum. The steel pan should be able to handle rethreading but the aluminum won't.

I would buy a thread chaser instead of a tap and die kit...a tap is for cutting away material to make new threads, a thread chaser will reshape damaged threads without removing any material. If the threads aren't majorly damaged then the thread chaser should be enough. If it's too bad then you'll need to use the tap to cut new threads and get a bigger drain plug.

How much force have you tried using to remove it? I've dealt with tons of drain plugs that would get tighter after a couple threads but would still remove and install okay. I usually try to just use the head of the ratchet or just the end of the wrench to get just a little bit more leverage. If it's still tight and you really need to force it out then you'll have to do something about it. But sometimes it just takes a little bit of extra force to get them out.

[Efthreeoh]

The bolt size is M12x16 (the bolt shaft size is 12MM and it is 16MM long). Standard thread pitch (course thread) for an M12 bolt is 1.75. Fine pitch is 1.5. I'm not sure what pitch the drain bolt is. But I'd guess 1.5. A finer thread pitch allows for better surface tension (friction) on the thread face at a lower torque value. Which is why you do not need to torque the living shit out of the drain bolt to make it tight...

My advice is get a new drain bolt from BMW and then measure the thread pitch with a thread gauge. That will assure you get the correct tap to rethread the hole. You'll want a new plug anyway because my bet is the plug is stripped and not the pan. The pan is steel (black) BTW on the 325i and 330i if it is a manual transmission. It is an aluminum pan if an automatic. If you are worried about metal shavings from the rethreading, just put some grease on the tap, that will hold the shavings to the tap. If you have a steel pan then just chase the hole with a magnetic pick up tool after tapping.

Now all that said, if you've not ever tapped a tread in a hole, I'd not start with an oil drain hole in an oil pan on your only vehicle. You can easily cross thread the hole with a tap. It takes "feel" to properly tap (rethread) an existing threaded hole, so it might be better to leave it to a BMW automotive shop. If you mess up the thread, then you'll have to tow the car to a shop to fix the oil pan. The cost of the tow will be more than the cost for an automotive shop to rethread the hole for you. If you chose that route, still get the new drain bolt from BMW and give it to the shop to do the work. The drain bolt is P/N 11137535106 for either version of the pan. Now the hole may not be repairable anyway, which would require resizing the hole and tapping to a new size, or installing a heil coil insert (it may not be possible to do so because the pan may be too thin), or a new pan is needed. With any of these cases, you'll want the car at the shop anyway.

[BB_cuda]

I will offer this but I have a 335d. I can't imagine the drain bolt being different. I bought a new bolt and took it to hardware store and found M12x1.5 is the threading. I ran a chaser up the female threading and it met no resistance. I had jacked engine up by oil pan but piece of 2x4 in contact with pan. I should not have let wood contact the drain bolt though. Mine was not stripped. For follow on oil change, I loosened with box end wrench without issue but the bolt couldn't be turned by hand even though loose.

As I mentioned above, I chased the thread and changed the bolt. It helped some but still isn't like it was before engine jacking.

I have to disagree about the tap though. Unless the threads are FUBAR at the very bottom oh hole, the tap is going to follow the existing threads until it hits the damaged areas. Use cutting oil and make sure to go backwards and forewards. If you hit hard resistance, back off. It wound totally suck to break tap off in the hole. If the M12 thread is hosed, just go to one size larger. I need to get that same tap to chase threads during my next oil change. Chaser didn't free it up enough. Another idea to get metal fragments is with bent pipe cleaners with grease on the tip. Perhaps use a boroscope camera to inspect after. Good luck to you, sir

[d_slice1]

Thanks for the advice and information guys! I think I'll do a combination of you're suggestions and maybe wait to do the oil pan gasket until an oil change or 2 down the line when I know if I need a new pan or not. And I drive an 06 MT so I believe it is steel (looks black) but realoem and tischer part # says it's aluminum? I must've looked at the wrong number.

Originally Posted by kkasson

How much force have you tried using to remove it? I've dealt with tons of drain plugs that would get tighter after a couple threads but would still remove and install okay. I usually try to just use the head of the ratchet or just the end of the wrench to get just a little bit more leverage. If it's still tight and you really need to force it out then you'll have to do something about it. But sometimes it just takes a little bit of extra force to get them out.

I've put more force on it then it takes to break it loose usually. It feels like the threads are running into interference. That being said, I didn't really wrench on it for fear of losing my only daily driver. And my mechanic did the same thing too for what it's worth. I'm gonna feel real silly if it just pops out and goes back in willy nilly.

My plan of attack is:
Buy a thread chaser and 2 taps, One same as stock, one oversized. I've heard they sell over sized drain plugs, so I may look into one of those too. I'll try the chaser first since it would be the easiest fix. Then move to a greased up tap if the threads didn't take. Then I guess oversized tap if stock size doesn't work. Worst case scenario, I wedge an oversized bolt in and cover it in jb weld to hold it until I get a pan. Anyone have suggestions for worst case scenario temporary plugs? Haha. I'll probably tackle this around Christmas time.

[djh2]

M12x1.5 is slightly smaller than 1/2-20, (nominally 12.54mm) so if you find the threads are stripped, you might be able to get the inch bolt to work until you can properly repair/replace the pan. Still would be the "plan c" option though.

Usually the drain plugs feel tight initially then hand unthread after you break them loose. This makes me think your pan threads might be OK but the end of the plug threads aren't great. I think if the pan threads were crossed, it would feel consistent across the plug.

Good luck!

[PhaseP]

Originally Posted by d_slice1

I think it's an aluminum pan but I may be mistaken there....

If it is black painted then it is steel, else it is aluminum.
I think all xi's regardless of transmission type and auto-transmission RWD's have aluminum oil pan. Manual RWD's have steel oil pan.

[Efthreeoh]

OP you have the same car as I do, it is a steel oil pan. Checked into (Googled) a "thread chaser" vs. just a plain old Tap and found a oil pan drain hole repair kit here:

https://www.google.com/url?sa=t&rct=...DOrKUnQFaODmzw

But this kit has a whole bunch of stuff you don't need. All you need is a M12-1.50 Tap and a tap handle. The problem is a M12-1.50 Tap is not commonly sold at hardware stores (because M12-1.75 is the common thread pitch for an M12 bolt). You're more likely to find a M12-1.50 Tap at an auto parts store since the common oil bolt M12 thread pitch is 1.50. I don't know what an actual "thread chaser" tool is. "Chasing a thread" is a procedure that you use a Thread Tap for reestablishing the same size threads a threaded hole. A "Die" is the tool you use to reestablish threads on a bolt. Perhaps a thread chasing tool is just another name for a Tap, or perhaps a Thread Chaser is a Tap that has some other type drive end on it other than a square drive, such as a hex-head (like a bolt) so that one doesn't need to buy a Tap handle to hold the tap. Using the link above, it has a link to O'Reilly auto part, which shows the BMW drain bolt thread size for the N52 is M12-1.50. Another Poster indicates that M12-1.5 is the correct thread size as well.

BB_Cuda's advice is the procedure used if establishing a new thread in a un-threaded hole. The flutes in the Tap are meant to provide a place for the cut metal "chips" to move to as you cut the new thread. The chips don't always get into the flutes cutting forward (clockwise) so the procedure is to back the Tap out a bit to move the chips into the flutes. The depth of the hole has a lot to do with the chance of jamming the Tap; the longer the hole the more chance. But you are just chasing threads in an established hole, so you'll not need cutting oil since the pan will be dripping engine oil, which will serve as the cutting lubricant. And the force required to chase the threads is far less than cutting new threads, also the depth of the hole in the pan is very shallow probably about 5 - 8 MM deep so there is most likely no chance to get chips jammed in the Tap and completely no chance of breaking off the (12MM) Tap in the hole.

Good luck with the repair.

[KNS]

Has anyone replaced the pathetic little drain plug with a better one? The E46 drain plug is much more stout and I've thought about switching - threads are the same I believe.

[kkasson]

Originally Posted by Efthreeoh

I don't know what an actual "thread chaser" tool is. "Chasing a thread" is a procedure that you use a Thread Tap for reestablishing the same size threads a threaded hole. A "Die" is the tool you use to reestablish threads on a bolt.

Thread chaser kit here: https://www.amazon.com/Lang-Tools-25...8V0/ref=sr_1_6

It's basically a tap that isn't sharp enough to cut away material.

If you use a tap on badly damaged threads it can cut away too much of it so that there aren't enough good threads left to hold the bolt securely. The thread chaser will try to push the old threads back into shape instead of cutting.

[Efthreeoh]

Originally Posted by kkasson

Thread chaser kit here: https://www.amazon.com/Lang-Tools-25...8V0/ref=sr_1_6

It's basically a tap that isn't sharp enough to cut away material.

If you use a tap on badly damaged threads it can cut away too much of it so that there aren't enough good threads left to hold the bolt securely. The thread chaser will try to push the old threads back into shape instead of cutting.

Thanks. I've seen those, but just assumed they were taps but with a different drive head on them. All I've ever used is a tap to chase treads. And those keep you from needing a bottom tap for blind holes.

[patents]

Several years ago we bought a used Honda Odyssey with about 90k miles. I go to change the oil, start to tighten the drain plug (with a torque wrench) and without hardly any effort at all (and not close to the torque spec) the threads broke loose. After cursing and throwing the wrench as far as I could (which isn't far when you are under a car and can't get a good swing), I take a look at it. The threads on the (aluminum) pan were gone. Totally smooth. Turns out the plug was an oversize tap bolt. I had some records of the previous owner taking it to a quick lube place for oil changes. Apparently they had stripped out the threads on the pan once before, used the oversized tap bolt, and I bought it with barely any threads left.

We were leaving the next day for a road trip vacation. I coughed up $500 and had the dealer put on a new oil pan. I didn't have time to try to figure out any heroic fix. There were no threads left, it had already been tapped out, and I just wanted it fixed right anyway.

And I don't think I've changed the oil myself on any of my vehicles since. I know it wasn't my fault, but I realized that economically the labor for an oil change at the dealer is minimal, I don't have to fool with getting and disposing of the oil, I don't get dirty and injured (I somehow managed a nice scar from changing oil), and if something goes wrong it's not my problem.

[natedog7700]

Re tap, or heli coil. Or replace the oil pan if you wish. Done.

[d_slice1]

As always, you all have enlightened me
Thanks for the much appreciated details. I'll triple check thread pitch before I buy a tap/chaser. I'll definitely start with the chaser though as I'm paranoid about about shavings getting in my pan. It may very well just be that my bolt threads gave in before my pan but I won't know til I pull it. And to think, I don't go to quick lube shops to avoid this type of issue Oh well. Live and learn I guess. Guess who ordered a torque wrench though... this guy!

[Don N.]

You can always put inserts in if the threads are too far damaged as well.

[CTinline-six]

Originally Posted by patents

Several years ago we bought a used Honda Odyssey with about 90k miles. I go to change the oil, start to tighten the drain plug (with a torque wrench) and without hardly any effort at all (and not close to the torque spec) the threads broke loose. After cursing and throwing the wrench as far as I could (which isn't far when you are under a car and can't get a good swing), I take a look at it. The threads on the (aluminum) pan were gone. Totally smooth. Turns out the plug was an oversize tap bolt. I had some records of the previous owner taking it to a quick lube place for oil changes. Apparently they had stripped out the threads on the pan once before, used the oversized tap bolt, and I bought it with barely any threads left.

We were leaving the next day for a road trip vacation. I coughed up $500 and had the dealer put on a new oil pan. I didn't have time to try to figure out any heroic fix. There were no threads left, it had already been tapped out, and I just wanted it fixed right anyway.

And I don't think I've changed the oil myself on any of my vehicles since. I know it wasn't my fault, but I realized that economically the labor for an oil change at the dealer is minimal, I don't have to fool with getting and disposing of the oil, I don't get dirty and injured (I somehow managed a nice scar from changing oil), and if something goes wrong it's not my problem.

That sucks!! I actually do all my own work just for that reason. I know exactly how tight the drain bolt is. Dealers and shops aren't much better. I've seen plenty of previously shop maintained vehicles with globs of RTV sealant on the drain plug. My friend had a 2001 Ford Ranger a few years ago and I used to change his oil for him. I had a final exam for college and couldn't do the change for him last minute before a trip, so he went to a local shop for an oil change. He was driving from CT to upper state NY about 8 hours. Halfway through the trip the oil light comes on. It becomes obvious there is a leak but he isn't sure from where. Turns out the shop loosened the filter I put on but never changed it. I unscrewed it one more turn and it fell completely off. There was about half a quart of oil left in the engine.

[Efthreeoh]

Originally Posted by d_slice1

As always, you all have enlightened me
Thanks for the much appreciated details. I'll triple check thread pitch before I buy a tap/chaser. I'll definitely start with the chaser though as I'm paranoid about about shavings getting in my pan. It may very well just be that my bolt threads gave in before my pan but I won't know til I pull it. And to think, I don't go to quick lube shops to avoid this type of issue Oh well. Live and learn I guess. Guess who ordered a torque wrench though... this guy!

OP and to anyone reading this thread. It is absolutely ridiculous to need a torque wrench to tighten a drain plug. As I explained earlier, most oil drain plugs use a fine-pitch thread (vs. course-pitch) so that you do not need to use a high torque value to tighten the plug and have it stay put. Fine pitch thread has more threads per inch (or millimeters if metric) that provides more surface area of threadface, which means there is more friction between the face of the thread on the bolt and the face of thread on the bolt hole for the same amount of torque applied to it vs. a course-pitch thread. Being there is more friction over the length of the thread for a fine-pitch thread, less torque is required to hold the drain plug in place.

Just properly thread the bolt into the hole; resistance means you are cross-threading it (i.e. the bolt is not perpendicular in the hole). Hand screw the drain plug into the hole until it fully seats and stops. Then take a ratchet wrench or a box-end wrench and lightly tap the end of the wrench with the side of your fist to set the torque; or, once the drain bolt seats, turn it another 20 to 35 deg. It's not rocket science (they build rockets with torque wenches BTW). I've probably done over 200 oil changes in the past 40 years or so and never once used a torque wrench, and I've never stripped a drain plug.

OP, getting a torque wrench doesn't mean you are out of the woods. What type of torque wrench did you buy? If you got a 1/2-drive click-type wrench then that's the wrong type because the torque value for an N52 drain plug is 18 pound-foot or 25 Nm (metric), and that big torque wrench does not have a small enough low-torque value to accurately set the torque at 18 ft-lb. The correct type of wrench is a 3/8-drive beam-style. Beam-style torque wrenches are accurate at low torque values; they are also the best to use when setting spark plug torque as well. A 3/8-drive click-type wrench is not correct either because most have a minimum setting of 10 - 20 ft-lb, which is not low enough. When using a torque wrench they are most accurate in the middle of their torque range, which means they are not accurate at 18 ft-lb. Most good mechanics know when a bolt is reaching an over-torque setting by feel.

If you are really up tight about this, because the BMW drain bolt uses a copper crush washer and you think you need to torque the living shit out of the bolt to get the copper washer to "crush" and seal properly (this really is the issue with most people...), O'Reilly's sells a M12-1.50 drain bolt with a rubber seal. BMW uses copper because it won't react to the steel oil pan and get stuck on the pan from galvanic reaction. You can use an aluminum crush washer if you want, if you change the oil a few times a year.

[patents]

Originally Posted by Efthreeoh

It's not rocket science (they build rockets with torque wenches BTW).

I can attest to that... and the torque wrenches must be regularly calibrated, certified, and a quality inspector has to verify the calibration certification and often has to re-torque behind the operator for verification. And log it all on the paperwork...

[d_slice1]

Originally Posted by Efthreeoh

OP and to anyone reading this thread. It is absolutely ridiculous to need a torque wrench to tighten a drain plug. As I explained earlier, most oil drain plugs use a fine-pitch thread (vs. course-pitch) so that you do not need to use a high torque value to tighten the plug and have it stay put. Fine pitch thread has more threads per inch (or millimeters if metric) that provides more surface area of threadface, which means there is more friction between the face of the thread on the bolt and the face of thread on the bolt hole for the same amount of torque applied to it vs. a course-pitch thread. Being there is more friction over the length of the thread for a fine-pitch thread, less torque is required to hold the drain plug in place.

Just properly thread the bolt into the hole; resistance means you are cross-threading it (i.e. the bolt is not perpendicular in the hole). Hand screw the drain plug into the hole until it fully seats and stops. Then take a ratchet wrench or a box-end wrench and lightly tap the end of the wrench with the side of your fist to set the torque; or, once the drain bolt seats, turn it another 20 to 35 deg. It's not rocket science (they build rockets with torque wenches BTW). I've probably done over 200 oil changes in the past 40 years or so and never once used a torque wrench, and I've never stripped a drain plug.

OP, getting a torque wrench doesn't mean you are out of the woods. What type of torque wrench did you buy? If you got a 1/2-drive click-type wrench then that's the wrong type because the torque value for an N52 drain plug is 18 pound-foot or 25 Nm (metric), and that big torque wrench does not have a small enough low-torque value to accurately set the torque at 18 ft-lb. The correct type of wrench is a 3/8-drive beam-style. Beam-style torque wrenches are accurate at low torque values; they are also the best to use when setting spark plug torque as well. A 3/8-drive click-type wrench is not correct either because most have a minimum setting of 10 - 20 ft-lb, which is not low enough. When using a torque wrench they are most accurate in the middle of their torque range, which means they are not accurate at 18 ft-lb. Most good mechanics know when a bolt is reaching an over-torque setting by feel.

If you are really up tight about this, because the BMW drain bolt uses a copper crush washer and you think you need to torque the living shit out of the bolt to get the copper washer to "crush" and seal properly (this really is the issue with most people...), O'Reilly's sells a M12-1.50 drain bolt with a rubber seal. BMW uses copper because it won't react to the steel oil pan and get stuck on the pan from galvanic reaction. You can use an aluminum crush washer if you want, if you change the oil a few times a year.

I was kinda just being an ass. I was considering a torque wrench but upon looking found exactly what you mentioned above. 3/8" clickers aren't sensitive enough because they shouldn't be relied on in the lower or upper 10%-ish of their range. I did order one though to have in my toolbox though - a precision instruments split beam, seemed to have the most praise around the web without the outrageous price of a snap on. And I plan on a getting a 1/4" soon. I've got to do the oil pan gasket eventually, (leak isn't terrible yet surprisingly -> 170k miles) and I'll need it for that. I've probably done 30-40 oil changes and never had a problem.
I was in a rush last time though... in a hurry to meet my lady... maybe didn't exactly have my head in the game. Haha. I also don't quite have the feel I used to have. I'm by no means a mechanic but I used to wrench on cars all the time. Rarely do more than oil changes now though. Just need to redevelop that feel.

Thanks efthreeoh. I had never heard of the galvanic reaction you wrote about. That's pretty interesting. I wouldn't trust any plastic washers on the oiled pan personally. I understand as long as the bolt itself is tight it's doing the bulk of the plugging but I don't trust plastic if it's heat cycled a ton. I like the copper crush washer. Just need to not literally try to crush it. Haha.

[Efthreeoh]

Originally Posted by d_slice1

I was kinda just being an ass. I was considering a torque wrench but upon looking found exactly what you mentioned above. 3/8" clickers aren't sensitive enough because they shouldn't be relied on in the lower or upper 10%-ish of their range. I did order one though to have in my toolbox though - a precision instruments split beam, seemed to have the most praise around the web without the outrageous price of a snap on. And I plan on a getting a 1/4" soon. I've got to do the oil pan gasket eventually, (leak isn't terrible yet surprisingly -> 170k miles) and I'll need it for that. I've probably done 30-40 oil changes and never had a problem.
I was in a rush last time though... in a hurry to meet my lady... maybe didn't exactly have my head in the game. Haha. I also don't quite have the feel I used to have. I'm by no means a mechanic but I used to wrench on cars all the time. Rarely do more than oil changes now though. Just need to redevelop that feel.

Thanks efthreeoh. I had never heard of the galvanic reaction you wrote about. That's pretty interesting. I wouldn't trust any plastic washers on the oiled pan personally. I understand as long as the bolt itself is tight it's doing the bulk of the plugging but I don't trust plastic if it's heat cycled a ton. I like the copper crush washer. Just need to not literally try to crush it. Haha.

If you screwed up because you had pussy on your mind, then we'll not cite you for a violation.

Simple as that.