Stuck spark plugs!! How to get them out?

[JonEQuest]

I just bought a 2015 M3 that runs rough. The shop the previous owner had it at tried to change the plugs and 2 of them (#1 and #6) are stuck. They didn't go further since they said they would probably break off in the head and the head would have to be pulled. Any suggestions? Any tricks to get stuck plugs out? is this a common thing on S55 engines? I have tons of experience with E9X cars and have rebuilt an N54 and a N55 but never ran into this issue before.

 

[fmorelli]

My opinion - I would spray PB Blaster down in there and let it sit for a day or so. Next I would make sure I have a good spark plug socket (American, German, or Taiwanese made, no shit Chyna stuff that looks shiny). I would then put a solid extension on it (non-wobble) and I would hit it with an impact with a few ra-tat-tat's.

Why? This is a breakaway torque issue. You want to hit very brief high torque hits to break it loose. Your other alternative is to put a big bar on it, but then that's a last ditch for me. You want the head cold in my opinion.

In the off chance that you strip the thread, you'll need to Time-sert.

Let's go to the solution. People say anti-seize, lube, ... . The issue is that no one cleans the lands and the threads when they remove the plugs. The lands and threads are always dirty. I clean them with a grab tool, a 2"x2" torn piece of paper towel sprayed with brake clean. Tear a bunch of pieces of paper, and use them one by one until they are clean. Clean the lands and the threads. If you are a gun buff, you can use gun cleaning copper round brushes. On a plug change you'll spend 10-15 minutes cleaning everything. It's worth it. Now when the plugs go in clean and are torqued, they'll come back out.

Good luck.

 

[JonEQuest]

My opinion - I would spray PB Blaster down in there and let it sit for a day or so. Next I would make sure I have a good spark plug socket (American, German, or Taiwanese made, no shit Chyna stuff that looks shiny). I would then put a solid extension on it (non-wobble) and I would hit it with an impact with a few ra-tat-tat's.

Why? This is a breakaway torque issue. You want to hit very brief high torque hits to break it loose. Your other alternative is to put a big bar on it, but then that's a last ditch for me. You want the head cold in my opinion.

In the off chance that you strip the thread, you'll need to Time-sert.

Let's go to the solution. People say anti-seize, lube, ... . The issue is that no one cleans the lands and the threads when they remove the plugs. The lands and threads are always dirty. I clean them with a grab tool, a 2"x2" torn piece of paper towel sprayed with brake clean. Tear a bunch of pieces of paper, and use them one by one until they are clean. Clean the lands and the threads. If you are a gun buff, you can use gun cleaning copper round brushes. On a plug change you'll spend 10-15 minutes cleaning everything. It's worth it. Now when the plugs go in clean and are torqued, they'll come back out.

Good luck.

Thanks for the advice. That sounds like a good plan. I planned to do the PB Blaster because that is the best I have used for anything stuck, but I didn't think about the taps with an impact to get that initial spin started. I bought this car for about 10k because the expectation from the shop the prior owner brought it to was that it would need an engine (or head pulled) when the plugs inevitably break off during removal. I am 90% sure I will get them out without them breaking off or even pulling the head if they do break off.

 

[fmorelli]

Thanks for the advice. That sounds like a good plan. I planned to do the PB Blaster because that is the best I have used for anything stuck, but I didn't think about the taps with an impact to get that initial spin started. I bought this car for about 10k because the expectation from the shop the prior owner brought it to was that it would need an engine (or head pulled) when the plugs inevitably break off during removal. I am 90% sure I will get them out without them breaking off or even pulling the head if they do break off.

Please report back and let us know how it goes.

 

[JonEQuest]

Please report back and let us know how it goes.

I got them out!!!!
I sprayed some PB Blaster down into thr holes and ran the car a few times to warm it up and let it cool down over a day. Then the next day I figured aluminum expands more than steel when hot so I warmed the car up again and slowly unbolted them. They were tight all the way out. After that I tie wrapped a paint gun cleaning brush (cleaners won't melt them) to a long screwdriver, wrapped that in paper towel sprayed in brake cleaner to clean out the shaft. Then after a few of those I we t back in with just the brush smoked in brake cleaner and twisted it in the actual plug threads to clean them a few times. Each time I brought the brush back out I sprayed it clean with brake cleaner. After a few times the brush was clean. Then I screwed a new plug in all the way and remove dot a few times. Each time there was some tan residue on the plug threads that a dry bristle brush got off easily. You can see it in the photo showing the brush and plug. After that the plug screwed in by hand very easy. For cyl #1 the plug spins in easy and stops right when the washer makes contact. I give it a little torque to secure it. BUT #6 the plug seems to get to a kind of tight but I don't feel a distinct stopping point. So I stopped. This was at night in my driveway since my garage door spring snapped 2 days ago. I plan to take out #1 and count the turns until it bottoms out. Then re-clean #6 and screw that plug in the same turns to make sure I go far enough but not too far. I may have just been 1 turn from done but didn't want to risk turning too far. Both plugs I removed looked fine and I saw no signs of cross threading or leftover aluminum on the plug threads. I may just need to clean #6 better. It was night and cold so I probably cleaned #1 better than #6 anyway.

 

[Krampus]

Did you use a torque wrench to tighten the plugs? 23Nm +-3Nm