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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Risk of breaking spark plug in cylinder head?



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      03-24-2014, 10:36 PM   #1
nukezero
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Risk of breaking spark plug in cylinder head?

It's going to be time soon to replace the spark plugs the 2nd time, 1st time by dealer.

I be reading some horror stories that some people have broken off the ceramic and snapped the spark plug inside the cylinder. This would undoubtedly cost thousands to fix.

I'm trying to understand and weigh in the risk and cost of doing it myself to save money, versus paying the premium to have the dealer do it and let the dealer assume all this risk.

I understand this isn't like when I change the oil, brake pads, oil filter housing gasket, or the water pump, those I did all myself and the risk is low. But this simple spark plug change could catastrophically set me back thousands if something goes awry.

Now does anyone know, what causes the spark plug to just snap off like that? Is it during the install or is it during the removal? I can't seem to fathom why it would snap off so easily.
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      03-24-2014, 11:13 PM   #2
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Install by hand never use more than a small 3/8 ratchet and medium force close to the head. Also FYI if you screw up any of your other DIY jobs and it leads to an accident i.e. loss of breaks. If your insurance can prove you failed to do the job correctly you are liable. If your asking these questions go to a good Indy mechanic for your maintenance.
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      03-25-2014, 09:37 AM   #3
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IMO this is not a BMW/N54 thing. This is a bosch thing.
I'm willing to bet you won't find a thread out there with this happening with our cars and NGK plugs.
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      03-25-2014, 10:16 AM   #4
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The recent thread you mention is the first time in 7 years that I've seen someone post about this in the n54 forum. Not saying it doesn't happen, just a reminder (possibly to myself!) to keep perspective.

The last time I snapped a bolt was a rear brake rotor bolt 8 years ago - at more than 50 ft pounds! I misread the torque settings and didn't realize the rears were supposed to be torqued different than the fronts.

This is a truly simple DIY, just make sure you have the right tools, correct metrics, and know how much to tighten, or what the torque specs feel like (practice on another bolt).
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      03-25-2014, 10:19 AM   #5
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Agreed with the above. I did mine not long ago and no issues. The past thread was also the first time I had seen anything like that. Just take your time and pay attention to what you're doing.
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      03-25-2014, 10:24 AM   #6
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I just did mine 2 weekends ago. I used Bosch plugs along with the spark plug tool off ECS. I hand tightened and didn't torque them. I figured if something went wrong tightening them I would get a misfire and they are easy to get at so I would just fix it. I also did not use any anti seize because from what I researched you didn't need to with these plugs.
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      03-25-2014, 11:04 AM   #7
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I used ngk plugs and torque wrench, no problem here. Just becareful
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      03-25-2014, 11:50 AM   #8
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Quote:
Originally Posted by nukezero View Post
I be reading some horror stories that some people have broken off the ceramic and snapped the spark plug inside the cylinder.
lol@ "some" stories...by which you refer to the ONE thread, which is still on the front page of this forum.

If you're that paranoid about it, just take it to the dealer. Either that or trade the car in for a Camry, which only requires you change the plugs every ~100k miles
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      03-25-2014, 01:08 PM   #9
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I've removed and installed NGK and back to Bosch and back to NGK over 4 times on this car. It's really not that risky. Just use the advice above, don't use a torque wrench. Go finger tight and I usually get 1/4 turn to taut is all after that with a 3/8 drive. You do not need to torque these suckers down, they are also held in place by the coils as well so they don't have a lot of opportunity to unscrew.

I'm a fan of torque wrenches in the right setting, but I've also cracked a few bolts with them...
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      03-25-2014, 01:12 PM   #10
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suck it up and do it. Once you do it knowing you have applied anti-seize to the threads and haven't over tightened the plugs you will feel more relieved about it. There is nothing you can do about a defective spark plug but every N54 on the planet uses these spark plugs and of every spark plug change on every N54 you have heard of this happening how many times? I'm pissed that I discovered by valve cover gasket is leaking but I'm also glad I didn't have to rely on the dealers word (I'll likely tackle that myself too cause I'll be damn if I'm paying a grand to have it done).
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      03-25-2014, 01:27 PM   #11
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Does everyone put anti sieze on their plugs? I didn't know people did this.
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      03-25-2014, 01:30 PM   #12
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Yeah, good questions:

1. Everyone says don't use anti-seize. But in all other cars, I'm told to use anti-seize like Hondas.

I remember when using anti-seize on my honda, it acted like a lubricant and made torquing down harder because it kept turning more and more.

2. I think NGK plugs are better right? But Bosch is OEM. However, if I buy NGK, I have to gap them myself? But if I buy Bosch, it's already pre-gapped?
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      03-25-2014, 01:32 PM   #13
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I've done it several times with no problems but always followed these rules:
* NEVER remove plugs when the engine is hot or even warm
* always use a BMW specific plug tool
* spray in a very small shot of PB Blaster, which helps break down the corrosion caused by two dissimilar metals touching (head to sparkplug threads)
* use shorter length 3/8th socket wrench
Hope this helps!
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      03-25-2014, 02:08 PM   #14
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Quote:
Originally Posted by stanlalee View Post
Once you do it knowing you have applied anti-seize to the threads
That's exactly how you can snap the plug... If you torque down a lubricated bolt, it takes much less force to snap it than if it were dry.

1) DO NOT APPLY ANTI-SEIZE ON THESE PLUGS!!!
2) DO NOT USE A SOCKET EXTENSION WHEN USING A TORQUE WRENCH.
3) WHEN USING A TORQUE WRENCH, TIGHTEN SLOWLY UNTIL IT CLICKS.
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      03-25-2014, 02:16 PM   #15
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Quote:
Originally Posted by nukezero View Post
I be reading some horror stories that some people have broken off the ceramic and snapped the spark plug inside the cylinder.
Can you please provide the links to the aforementioned "stories" you have read here?
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      03-25-2014, 02:30 PM   #16
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Quote:
Originally Posted by Gizm0 View Post
2) DO NOT USE A SOCKET EXTENSION WHEN USING A TORQUE WRENCH.
At the risk of spreading misinformation, can you please provide a link to your statement?

I have read the opposite.

http://home.jtan.com/~joe/KIAT/kiat_3.htm

Torque Wrenches and Accessories

From time to time people have asked me if it is OK to use an extension with a torque wrench. The answer is yes. Using an extension or reducer with a torque wrench does not affect the accuracy. Others have asked if it is OK to use a universal joint with a torque wrench. The answer is NO. Universal joints change the torque as the drive angle increases. I checked this out with my torque tester. The results are shown in Figure 8c. Don’t use universal joints with torque wrenches.
.
.
If you were to increase the length of the torque wrench handle, that's another story, and there's a formula to calculate the resulting force.

http://www.freeinfostuff.com/TorqueE...eExtension.htm
.
.
.

Last edited by Lotus99; 03-25-2014 at 02:43 PM..
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      03-25-2014, 02:40 PM   #17
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Quote:
Originally Posted by Lotus99 View Post
At the risk of spreading misinformation, can you please provide a link to your statement?

I have read the opposite.
I stand corrected. I have always been told not to use a socket extension while using a torque wrench because it would false the torque applied. It didn't really make much sense from me, but still I took it for granted without questioning if it was right or wrong because I was told from older, seemingly wiser folks with mechanical knowledge.

Thanks for teaching me something today.
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      03-25-2014, 02:46 PM   #18
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Quote:
Originally Posted by Gizm0 View Post
That's exactly how you can snap the plug... If you torque down a lubricated bolt, it takes much less force to snap it than if it were dry.
Key word is IF you over tighten them. I can't possibly over tighten them unless my hand has the power and leverage of a socket tool. Once hand tight I tighten them with the socket just enough to ensure they don't back out. I concede technically your right but I'm not concerned about breaking them during install (I'm pretty confident I tighten them less my way than the correct way with a torque wrench), I'm concerned about removal
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      03-25-2014, 03:29 PM   #19
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no anti-seize. no torque wrench.
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      03-25-2014, 03:46 PM   #20
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Sounds good guys, I will give this a shot soon. It is confusing when you say torque wrench socket extension because how can you not use a socket extension to get down into the spark plug hole?

I think you meant to say torque wrench handle extension?
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      03-25-2014, 03:51 PM   #21
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Quote:
Originally Posted by nukezero View Post
Yeah, good questions:

1. Everyone says don't use anti-seize. But in all other cars, I'm told to use anti-seize like Hondas.

I remember when using anti-seize on my honda, it acted like a lubricant and made torquing down harder because it kept turning more and more.

2. I think NGK plugs are better right? But Bosch is OEM. However, if I buy NGK, I have to gap them myself? But if I buy Bosch, it's already pre-gapped?
1) No anti-seize
2) Can't speak to the NGK plugs, but Bosch is OEM and is gapped, no need to gap yourself.

FYI - if you go to Bosch's website:
http://www.boschautoparts.com/Vehicl...artFinder.aspx

Enter your information and select 'spark plugs', you will see Bosch's part number is ZGR6STE2

If you click on the 'Support' tab for that plug, there is a PDF detailing generic information about Bosch plugs. In that PDF is a section marked 'Important, Please Read' where they claim:

Quote:
Bosch Spark Plug threads are rolled and nickelplated eliminating the need to use anti-seize compound (if anti- seize material is used, reduce the torque recommendations by 30%)
FYI - BMW's torque specification for the Bosch plug is 23 Nm (16.9 ft-lbs).

This is not a difficult job, but I personally feel either the BMW spark plug socket or a comparable spark plug socket purchased from a reputable vendor (e.g. Turner, ECS, etc.) is essential for the job.
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      03-25-2014, 03:54 PM   #22
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FYI antiseize will actually change the torque applied to a bolt or stud. Any of the aluminum fastners and spark plugs etc. Should all be assembled dry.
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