[queensfield]

My 2006 330i, E90 started showing up rough idle and slight shaking. Read the codes and it seems like cylinder #2 was misfiring. Changed the spark plug and coil today. But I tightened to about 25 N-m. Then, someone told me it should be 30 N-m. Should I open up again and tighten to 30 N-m? Thanks.

[GetSomeE92]

Google the spark plug torque specs of your specific model to be sure, but I know the plugs for the 335i are supposed to be tightened to 17ft-lbs (23 nm)

[1QuikWS6]

Bentley lists Spark Plug torque for all following models as 23 +/-3 Nm (18 +/-2 ft-lb)

2006-2009
325i, 325xi, 328i, 328xi, 330i, 330xi, 335i, 335xi

So your torque of 25 Nm is within the spec...

You should also use a light coating of copper based anti-seize on the plug threads

[jacobsed]

Are you sure about that copper anit seize? I thought you were supposed to put them in dry to get the correct torque spec.

Originally Posted by 1QuikWS6

Bentley lists Spark Plug torque for all following models as 23 +/-3 Nm (18 +/-2 ft-lb)

2006-2009
325i, 325xi, 328i, 328xi, 330i, 330xi, 335i, 335xi

So your torque of 25 Nm is within the spec...

You should also use a light coating of copper based anti-seize on the plug threads

[GetSomeE92]

Originally Posted by jacobsed

Are you sure about that copper anit seize? I thought you were supposed to put them in dry to get the correct torque spec.

I don't believe you are supposed to use any anti-seize. I haven't used any and I didn't see any on the plugs the dealer just installed for me under warranty.

[1QuikWS6]

Originally Posted by jacobsed

Are you sure about that copper anit seize? I thought you were supposed to put them in dry to get the correct torque spec.

The Service Manual specifically states to use a light coating of copper based anti-seize on the plug threads, or I wouldn't have included it in my statement. But I'm sure there will be replies by the usual 'internet' mechanics/engineers that feel they know better than the BMW engineers that designed the car


I've worked as a Mechanical Design Engineer in several industries (including automotive) since 1982. For what it's worth, based on my experience:

There are no absolute rules where thread lubricant is concerned. When a lubricant is required it is usually specified in the shop manual (as in this case). As a general rule head bolts engaging cast iron should be lubricated with oil, and ANY thread engaging aluminum should be lubricated with an anti-seize compound - typically because there is a corrosion or galling issue-as is the case with spark plugs with their fine thread pitch and dissimilar metals in intimate contact .

• When you tighten a fastener to a torque value the engineer providing the torque value was trying to achieve a specified stretch of the bolt to deliver the calculated clamping force needed to overcome operating loads without subjecting the fastener to fatigue. If the clamping torque is insufficient to prevent the fastener from being cycled while the machine is in operation (by cycled I mean being loaded then unloaded to the point where the fastener relaxes over and over), the material will experience conditions similar to a wire clothes hanger when you bend it back and forth. It breaks.
  
• The target for most fastener designs is to have the bolt or stud preloaded to 65% to 80% of its yield strength. If you need more clamping force you use a larger fastener. The clamping force is transferred to the joint member(s) by a washer under the moving member of the fastener during assembly. In some cases there can be a through bolt or stud with a potentially moving member on each side, in which case there is a washer on both sides of the joint. The washer is really intended to provide a replacement bearing surface, usually of a material that is not as hard as the fastener, so that at the next assembly the joint bearing surface can be replaced (or, for those of us without a box of new washers for every job, resurfaced using a sanding block to remove grooves and galled washer material) without much trouble. In most cases the washer is of a larger diameter than the fastener, which can also serve to spread the load somewhat under the fastener, however, unless the washer is unusually thick, this is not likely a significant aspect of the joint design.
  
• The amount of axial load that is generated by torque on the fastener is controlled by the coefficient of friction between the various moving surfaces of the fasteners, which is controlled by too many aspects of the fastener system to be reasonably accurately known, even in new conditions. Thus you see many newer assembly bolt torque specifications based on bolt or nut turning degrees after a joint seating step based on torque (where the coefficient of friction has a limited effect on the fasteners as there is no real axial load jamming the surfaces together). This is because the telling feature, the actual coefficient of friction between the moving surfaces ranges by nearly an order of magnitude in new fasteners (actual surface finish in the load bearing areas, how the lubricant was applied, how clean the parts and lubricant are, any coatings and their actual dimensions, the perpendicularity of the joint flanges and fastener, etc.). Setting fastener preload by turns is more accurate because the thread dimensions (threads per unit of length) can accurately determine axial stretch.
  
• Using a lubricant, and how it is applied, is a critical aspect establishing a coefficient of friction, and therefore of how torque is turned into axial stretch. If the lubricant is not used when it is called for, the coefficient of friction will increase to the point where the fastener is likely not sufficiently preloaded - you will reach the torque value before the fastener is stretched because you are consuming the torque overcoming the friction.
  
  -Conversly-
  
  If the fastener is lubricated when it was not supposed to be lubricated, the specified torque will likely cause yielding, or even snap the stud or bolt as more turns will be achieved due to the lower coefficient of friction. Reusing washers that are buggered up is another way to jeopardize the integrity of the joint design. At the very least, turn the washer over to present the better condition surface to the bolt head or nut. I typically sand off the washer face marks and any galled material with sand paper wrapped around a block with flat surfaces.

Don't gob the stuff on, a very small ribbon down the length of the threads is sufficient...

[David1]

Originally Posted by GetSomeE92

I don't believe you are supposed to use any anti-seize. I haven't used any and I didn't see any on the plugs the dealer just installed for me under warranty.

Correct, no anti-seize is to be used. The threads are coated (anodized )from the plug manufacturer.

[David1]

Originally Posted by ndog14

OEM plugs? This winter I will be replacing mine but I'm going to go with NGK's.

Either one.

[Bamaben]

As a general standard I hand thread until it stops then using socket wrench I turn 1/4 turn. Done this my whole life and never had a problem.

[335BBS]

Originally Posted by Bamaben

As a general standard I hand thread until it stops then using socket wrench I turn 1/4 turn. Done this my whole life and never had a problem.

Funny...exactly what I've done for 35 yrs too. Never a problem.

[David1]

If you fart while torqing it, it is to tight!

[NoTempoLimitN54]

Originally Posted by David1

Correct, no anti-seize is to be used. The threads are coated (anodized )from the plug manufacturer.

You can't anodize steel, only aluminum and titanium. Most spark plugs I've seen have an iridite coating, or they may be aluminized (thin Al coating on the steel).

The head isn't anodized either, at least not in the spark plug holes, because the anodize coating does not conduct electricity (its made up of hard aluminum oxide). Also, the aluminum head cannot be hardened AFAIK.

I think the benefits of a thin coating of copper anti-sieze on spark plugs on our aluminum heads far outweigh the downside. Or to put it another way, the downside of getting a plug stuck and damaging the thread in the aluminum is a far worse outcome than anything that could potentially happen because you used anti-sieze.

Some people think the torque should be increased if you use anti-sieze, others do not. I use the same torque spec.

[queensfield]

The outside is normally plated with Zinc, which peels off from the spark plug when removing. Some plugs are also plated with nickel, which has a greyish appearance. I used NGK, which were whitish and are probably zinc plated. Here is a link to NGK's recommendation regarding use of anti-sieze.
http://www.ngksparkplugs.com/pdf/TB-...1antisieze.pdf

[1QuikWS6]

Originally Posted by queensfield

The outside is normally plated with Zinc, which peels off from the spark plug when removing. Some plugs are also plated with nickel, which has a greyish appearance. I used NGK, which were whitish and are probably zinc plated. Here is a link to NGK's recommendation regarding use of anti-sieze.
http://www.ngksparkplugs.com/pdf/TB-...1antisieze.pdf

Good information - and true. If plug already has anti-seize coating applied from mfg. - then no additional is needed.

Apparently, the Bentley Service manual was written when typical plugs used did not have this thread coating...

[jacobsed]

haha....you must have a small penis to author a reply this long and show off how smart you think you are

Originally Posted by 1QuikWS6

The Service Manual specifically states to use a light coating of copper based anti-seize on the plug threads, or I wouldn't have included it in my statement. But I'm sure there will be replies by the usual 'internet' mechanics/engineers that feel they know better than the BMW engineers that designed the car


I've worked as a Mechanical Design Engineer in several industries (including automotive) since 1982. For what it's worth, based on my experience:

There are no absolute rules where thread lubricant is concerned. When a lubricant is required it is usually specified in the shop manual (as in this case). As a general rule head bolts engaging cast iron should be lubricated with oil, and ANY thread engaging aluminum should be lubricated with an anti-seize compound - typically because there is a corrosion or galling issue-as is the case with spark plugs with their fine thread pitch and dissimilar metals in intimate contact .

• When you tighten a fastener to a torque value the engineer providing the torque value was trying to achieve a specified stretch of the bolt to deliver the calculated clamping force needed to overcome operating loads without subjecting the fastener to fatigue. If the clamping torque is insufficient to prevent the fastener from being cycled while the machine is in operation (by cycled I mean being loaded then unloaded to the point where the fastener relaxes over and over), the material will experience conditions similar to a wire clothes hanger when you bend it back and forth. It breaks.
  
• The target for most fastener designs is to have the bolt or stud preloaded to 65% to 80% of its yield strength. If you need more clamping force you use a larger fastener. The clamping force is transferred to the joint member(s) by a washer under the moving member of the fastener during assembly. In some cases there can be a through bolt or stud with a potentially moving member on each side, in which case there is a washer on both sides of the joint. The washer is really intended to provide a replacement bearing surface, usually of a material that is not as hard as the fastener, so that at the next assembly the joint bearing surface can be replaced (or, for those of us without a box of new washers for every job, resurfaced using a sanding block to remove grooves and galled washer material) without much trouble. In most cases the washer is of a larger diameter than the fastener, which can also serve to spread the load somewhat under the fastener, however, unless the washer is unusually thick, this is not likely a significant aspect of the joint design.
  
• The amount of axial load that is generated by torque on the fastener is controlled by the coefficient of friction between the various moving surfaces of the fasteners, which is controlled by too many aspects of the fastener system to be reasonably accurately known, even in new conditions. Thus you see many newer assembly bolt torque specifications based on bolt or nut turning degrees after a joint seating step based on torque (where the coefficient of friction has a limited effect on the fasteners as there is no real axial load jamming the surfaces together). This is because the telling feature, the actual coefficient of friction between the moving surfaces ranges by nearly an order of magnitude in new fasteners (actual surface finish in the load bearing areas, how the lubricant was applied, how clean the parts and lubricant are, any coatings and their actual dimensions, the perpendicularity of the joint flanges and fastener, etc.). Setting fastener preload by turns is more accurate because the thread dimensions (threads per unit of length) can accurately determine axial stretch.
  
• Using a lubricant, and how it is applied, is a critical aspect establishing a coefficient of friction, and therefore of how torque is turned into axial stretch. If the lubricant is not used when it is called for, the coefficient of friction will increase to the point where the fastener is likely not sufficiently preloaded - you will reach the torque value before the fastener is stretched because you are consuming the torque overcoming the friction.
  
  -Conversly-
  
  If the fastener is lubricated when it was not supposed to be lubricated, the specified torque will likely cause yielding, or even snap the stud or bolt as more turns will be achieved due to the lower coefficient of friction. Reusing washers that are buggered up is another way to jeopardize the integrity of the joint design. At the very least, turn the washer over to present the better condition surface to the bolt head or nut. I typically sand off the washer face marks and any galled material with sand paper wrapped around a block with flat surfaces.

Don't gob the stuff on, a very small ribbon down the length of the threads is sufficient...

[1QuikWS6]

Ya - just another internet punk...

Sorry I tried to give an intelligent answer instead of the 3 word sentences you're used to being able to comprehend

So you can kiss my

[N8N]

Originally Posted by 1QuikWS6

The Service Manual specifically states to use a light coating of copper based anti-seize on the plug threads, or I wouldn't have included it in my statement.

Does it actually say "copper based anti-seize"?

Where does one buy such stuff?

I've been using the Permatex aluminum anti-seize for years; I dimly recall having seen a copper based anti-seize but I just stopped in two parts stores and called two more and they only have the Permatex aluminum stuff.

I will be using the factory Bosch spark plugs as soon as they show up (I couldn't get them at any local parts stores either, not even NAPA or Carquest which are usually the best ones) and normally I would just use the products I've used my whole life, but I would really hate to have to helicoil a BMW head because I did and it turned out to be the wrong thing to do. Is there any real downside to using the Permatex product?

And before you ask, yes, I did order the Bentley manual, but it hasn't shown up yet either...

[1QuikWS6]

Yup, Section 020, page 44 @ bottom of page along with torque specs.

You would think it would be relatively up to date as it was published in 2009

There are several mfg. of Copper based A-S

• FelPro/Loctite Hi Temp C5-A #51007
• Bostik Never-Seez
• Permatex Copper Based #09128

I would have thought the Permatex would be the easiest to find in an auto parts store. I have the FelPro/Loctite

[jacobsed]

That is super interesting.

Originally Posted by 1QuikWS6

Yup, Section 020, page 44 @ bottom of page along with torque specs.

You would think it would be relatively up to date as it was published in 2009

There are several mfg. of Copper based A-S

• FelPro/Loctite Hi Temp C5-A #51007
• Bostik Never-Seez
• Permatex Copper Based #09128

I would have thought the Permatex would be the easiest to find in an auto parts store. I have the FelPro/Loctite

[NoTempoLimitN54]

Originally Posted by queensfield

Here is a link to NGK's recommendation regarding use of anti-sieze.
http://www.ngksparkplugs.com/pdf/TB-...1antisieze.pdf

Great info from NGK. I didn't know the zinc plating would shed like that. Most zinc plating on steel is just sacrificial to prevent corrosion.

All that said, I personally would still use a very light coating of copper anti-sieze. I'm talking a super-thin see-thru coating applied with a small brush, not a big glob like some people do. Just a little bit at the thread start, it will distribute as you thread the plug in. Think of it more as assembly lube.

Use of a good quality torque wrench is essential. I followed the above procedure with my E39. Plugs were in and out quite a few times. Never had any problems -except- for one plug that got stuck (it was installed before I bought the car).

[David1]

Originally Posted by queensfield

The outside is normally plated with Zinc, which peels off from the spark plug when removing. Some plugs are also plated with nickel, which has a greyish appearance. I used NGK, which were whitish and are probably zinc plated. Here is a link to NGK's recommendation regarding use of anti-sieze.
http://www.ngksparkplugs.com/pdf/TB-...1antisieze.pdf

That is what I meant.