I've had my car ('04 MC) for a couple weeks now, and I can't seem to leave it well enough alone. I was a little disappointed with the performance and mileage, so I've been poking around a little bit. Tires were underinflated, so I fixed that. But I also took a look at my spark plugs. 52,000 miles on the car. The ignition wires are stamped "2003" so I'm guessing they're original. Not sure about the plugs, as they're NGKs.

The picture on the left is the spark plug from my #1 cylinder. The picture on the right is what a NGK BKR6EQUP looks like new.



As far as I can tell, it looks like my engine is running well (all the other plugs looked just like that one). But I don't know if they're worn out enough to justify replacing them. Perhaps someone with a more experienced eye could weigh in...

Thanks!

 

What does the owner's manual recommend? If I am not mistaken that is a copper core plug and probably wouldn't hurt to replace. I just replaced the plugs on my Silverado this weekend...they had platinum core and I figured at 122K miles it was time .

 

I am not sold on life time plugs or those which are "supposed" to be left in for 100K.

First off, good luck removing them after being in that long......secondly, there are parts to the plug not visible, and potential damage which can go unseen.

I have a MCS so I change mine about once a year. I would think in a MC, you can go bit longer. 52K miles may be too long though.

Torque them down to specs btw. So good call, and check the air filter while your in there too, that will lower MPG's as well.

 

They are about $24, easy DIY..... so why not? You already have 1/8 of the job done by pulling out one plug.

 

Nothing is "life time" - plug, wires or oil; they all degrade over time. I replaced plugs at 30k on an '04 just-a-Mini and noticed a difference . I'd replace them if I were you. Same with the wires. This is just like the "recommended" oil changes that BMW states for the car. There are a lot of post about how bad that is for your engine. While you are at it, throw in an air filter. Wait a minute, that was gRayrAvEn's line . You want your car to last, take care of it the old fashion way.

On these engines the spark plugs should be loosened and retorqued about every 20k miles otherwise you run the risk of the plug seizing on the head and ripping the threads out when you do get around to changing them.

 

Also, take care removing the plugs. Unscrew them a little and then screw them back in a little. Working them out slowly that way will help to keep the theads from binding up.

 

+1 ^

FWIW I changed mine out at 50,000. They didn't look bad, but for the cost & 15 minutes of time it was worth it. Leaving a plug in for 100,000 worries me a bit. Like what if they do not want to come out.

At your mileage I'd also recommend a set of plug wires. Another easy cheap thing to do.

 

Thanks guys. I think I'll probably just change 'em, since it's easy and it's not terribly expensive and it'll make me feel better, if nothing else. I guess the car will be due for the "Inspection II" soon, which calls for changing out all that stuff anyway, right?

I got all 4 plugs out, no problems. Couple of 'em were torqued to about 30 ft.-lbs, but nothing more than that, and they all came out easy. The engine compartment is very, very clean and everything's in great shape. Will definitely use anti-seize when I put the new plugs in, and I'll probably check the torques every once in a while just based on what I've read here about MINIs throwing out spark plugs that loosen up!

I'll check out the air filter, too. All the ones they had listed on the Autozone website were washable and cost about $45, which seems a little excessive for me. Maybe BAP-GEON (where I'm going for the plugs) will have something a little more reasonable.

The wires look fine, but they're original, so maybe I should do those, too. On my very first car ('85 VW Cabrio, in 2002) I replaced the wires and plugs when one cylinder stopped firing. If you touched the wires with the engine running, you could feel the spark each time it tried to fire. I'm not there yet with the MINI, but I don't want to ever get to that point again, either.

Not many things more satisfying than making your car run better. I've just done plugs, wires, caps, and rotors on my other two cars currently in my driveway, which have 250,000 miles between the two of them. Sure makes a difference sometimes. I'll let you know how it goes with the MINI...

 

Change the plugs, it can't hurt and may even help. Make sure to use a little anti-seize on the treads and dielectric grease at the wire connection. Check the manual, but I believe the spec is 20 ft lbs of TQ.

Your wires are likely still good, if you are concerned though measure the resistance of each one, and look for something outta whack. Likely they will all be below 5K and that means they are plenty good. However, if you want to change them to get a color (i.e. red, blue, etc) then go for it.

Do check the wire connection to the coil. Clean/sand/wire brush if any corrosion and then use dielectric grease here as well.

 

Just a reminder, if you use anti-seize the torque spec changes. Unfortunately, I don't know what the conversion would be.

 

Guys guys guys, Anti seize compound on your spark plug threads is a BIG NO, it creates a thermal barrier reducing the spark plugs ability to do what it should be and needs to be doing, and that is thermal transfer between itself and the cylinder head!

It may make removal easier for you in the future, however it is NOT a good idea, and besides of which, you have now introduced a slipping compound to the threads, and if you've got a lean running cylinder, this can and does create heat harmonic vibrations, and these are the reason we sometimes get spark plugs loosening or blowing out of the cylinder altogether, aided by your application of Anti seize slipping compound!

Ok some simple basics first, whenever you decide to remove re-install your existing spark plug (removed for checking/cleaning or diagnostic work) or a new set, you should be aware of the spark plug tightening torque, in this case 20-25nm (15-20 lb/ft for the old school) this is VERY important to the compression of the sealing gasket (washer) a new spark plug has a sealing gasket thickness between 2.34-2.8mm when the correct amount of torque 20-25nm (15-20 lb/ft) is applied to your spark plug, then you will have reduced the sealing gasket to between 1.8-1.96mm this is the optimum compression for the sealing gasket, as you over tighten then you further reduce the sealing gasket, and when the sealing gasket is reduced to below 1mm then you are running into a whole world of trouble, much easier for the spark plug to become loose, from reduced heat expansion of the sealing gasket (washer) and possible heat harmonic vibrations.

As you continue to over tighten the spark plug, yes you can appear to get the spark plug very tight, however all you have done is to stretch the spark plug (yes stretch) and open the spark electrode gap as well as break the contact seal with the ceramic, the joint between the steel and ceramic is a interference seal fit not a adhesive bond for obvious reasons.

At this point you now have a heat vibration issue, as the seal between the steel body and ceramic centre has been broken, the spark plug has lost it's ability to transfer heat and is now subject to vibration harmonics, and yes you've guessed it, the harmonic vibration will and does undo the spark plug, hence why sometimes you check and find a loose spark plug not long after you have checked it!

And in a worse case scenario the spark plug can unwind sufficiently to damage the threads and be blown out of the cylinder head.

Now I have touched on the heat harmonic vibrations, here is a little bit more, as you increase power or have a lean running cylinder in your engine you in turn increase cylinder temperatures, this puts the stock spark plug into a situation where it can't control the raised temperature and begins to overheat, this then has the effect creating a heat harmonic vibration, and as stated before, can loosen itself over time!

The term spark plug heat range refers to the speed with which the plug can transfer heat from the combustion chamber to the engine cylinder head, via the threads of the spark plug, DO NOT USE Anti seize compound, it has been found the optimum combustion chamber temperature for petrol engines is between 500 degrees C – 850 degrees C when it is within this range it is cool enough to avoid pre-ignition and plug tip overheating which can cause engine damage, (remember thermal transfer and heat harmonic vibrations) while still being hot enough to burn off combustion deposits which cause fouling.

The spark plug can help maintain the optimum combustion chamber temperature, via thermal heat transfer, into the engine cylinder head, via the threads of the spark plug body, this is reduced if you apply Anti seize compound!

There are lots and lots of other factors to bring into the equation of cylinder temperature, and the effects of poor thermal transfer and heat harmonic vibrations, but for now I hope the above has given a clear indication of why it is bad practice to apply Anti seize compound.

 

Czar, do you manufacture spark plugs in your spare time? You are a wealth of knowledge and an asset to the community. Thank you.

 

I wish I had some spare time After 26 years in the Racing industry, I have collected a wealth of knowledge, no I don't manufacture spark plugs, I just try to help wherever I can, and thank you for your comment.

 

I thought anti seize compound was actually a good conductor of heat, due to it's aluminum (sometimes copper) content.

 

Wow...

Thanks again, czar!

I find it funny that every time you purchase spark plugs at an Auto Zone or Advance Auto Parts, they "throw" in 2 packs of Anti-Seize (that you must still pay for) and tell you to make sure you put it on the threads.

Another case of something that "helps" you actually hurting your car in the long run.

 

In their own rights the properties of copper and aluminium Anti seize compounds are good thermal conductors, however when applied to the threads of spark plugs, they interfere with the thermal transfer flow!

Also when applied to the threads of spark plugs, you get an inaccurate torque reading (under rating) and this can lead to the spark plugs being torqued to tightly, squashing the sealing gasket (washer) to beyond it's working tolerance, as mentioned earlier in the post above, and the possibility of damaging the very delicate Aluminium threads!

 

czar-

Thank you for the information and advice. Do you think it's wise to apply a film of dielectric grease to the inside of the plug boot? FWIW I plan on changing my plugs every two years and I'm not convinced that the grease in the boot is necessary. Seems that it would be beneficial at the outside (in a very thin film) of the wire connection at the coil. I dunno.

Thanks again.

 

Uhhhhh...

So, now what? I threw the new plugs in yesterday, with a nice coating of anti-seize. I torqued them to 21 ft-lbs.

Based on what I'm reading here, I probably actually over-torqued them, smashing the little crush fitting more than it's supposed to be.

So I guess I could pull them out, wipe the goo off, and put them back in with the proper torque, but would they seal properly now that they've been torqued with anti-seize?

The NGK website actually has some really in-depth information about their plugs. The plugs in question have a special coating on the threads to prevent corrosion, thereby rendering anti-seize unnecessary.

For older, cheaper plugs, it's probably a good idea. But it seems, as near as I can tell, that it's at best not needed and at worst harmful.

Car runs nice on the new plugs, though. The old ones had "NGK" stamped on one side and "BMW" stamped on the other, so I'm guessing they were factory originals and had 6 years and 52,000 miles on them. Probably installed without anti-seize, and came out easily enough.

 

The use of dielectric grease is in itself an insulator, what I mean is although it does keep out moisture it also can lock in moisture too!

Moisture can develop from component sweating, this is quite common, especially if you have washed your engine, and although it may appear dry, there will be a build up of moisture, even a small amount of water around the spark plug down the tube, and when the engine is run this boils away (like a kettle) and creates moisture in the spark plug boot.

Just make sure your components are really dry (air dry) if you are going to use dielectric grease, or not, whichever the case maybe.

Simply remove your spark plugs, clean the Anti seize off thoroughly, and re-install, using your previous torque setting 21 ft lbs they will seal ok.

Your old spark plugs do sound like they are the factory originals.

 

Okay, I guess I'll wipe 'em off. Maybe I should wipe it off the Toyota and the Honda I just did within the last two weeks, too.

Trouble is, now that goo is on my head, too. Any tips for cleaning it out of there? What can I use to reach down in there and clean up a little? Guess I could use a rag and a dowell or something, but I don't want to get anything down that hole that doesn't belong there...

I used my torque wrench to remove the plugs, and noticed that they broke loose at 15-20 ft-lbs after I'd re-installed them after looking at them on Saturday. I'd driven about 60 miles. Should I expect to re-torque my plugs? How often, and how long until they settle in and stay put?

 

Thanks, czar. Great information.

 

The way I would clean out the threads, would be to use the reverse thread chaser tool, this is a fantastic piece of kit, it allows the thread chasing to be done counterclockwise, from the inside out! Google it and you will see what I mean.

Once you have installed your spark plugs correctly, there should be no need to re-check them, however for piece of mind, there is no harm in re-checking after a couple of weeks or so, they do not have a settle in period.

One more point, this is important, NEVER fit your spark plugs into a hot engine, always fit them into a cold engine! remember expansion and contraction from school, well this applies now!

If you fit when the engine is hot, as the engine cools then the contraction of the alloy comes into play, and what was a correctly torqued tightening when hot is now becoming an under torqued tightening as the alloy contracts on the spark plug seat area, hot cylinder head vs cold spark plug, both are now contracting and expanding at different rates!

 

Thanks for the advice! I'm proud to say, though, that I figured out the cold engine thing by myself. I only ever do anything with the plugs when the engine is cold, like first thing in the morning or after it's been sitting for at least 4-5 hours.

I've never really paid so much attention to the finer points of a car I've owned, but I gotta say this is kinda fun. I like learning new skills, especially when they can save me money and give me the peace of mind of knowing it was done right because I did it. I spent a lot of (my own) money on this car, and I really want to keep it nice and get the most performance and longest life I can out of it.

Just another hour or two until I finally get to drive it again!

Thanks, everybody, and happy motoring!

 

Sorry but I must disagree. Basically, the higher the friction between threads, the less load that will be appled to the seat and it will be less likely that you will seat the plug. Basically, threads are nothing more than 2 wedges put together and they need to slide against each other to perform their function. That function is to translate a rotational force into an axial force which seats the plug. Also, because of that friction, it will be more likely that you will damage the threads due to galling when you do torque them down or try to loosen them.

Also, there is no thermal insulating value to the anti seize compound. It is too thin to be an effective insulator even if it had a high insulating value. Heat transfer is by conduction, convection and radiation. In the case of a spark plug thread there is only conduction because the two pieces are in contact. There will be some contact resistance because of the small spaces that exist between any two surfaces, but the anti seize compound will fill in those spaces and make the heat transfer better not worse.

Bottom line is, Brownshoe did the installation correctly the first time. The plugs are not over torqued; they were properly torqued. Also, more than likely the plugs you pulled out were install with anti seize at the factory, which is why they came out easily. And you never had problems with them.

 

Well Eddie07S, it wouldn't do for us all to agree!

As the threads on the spark plugs are coated with a dry Anti seizure/corrosion material (Nickel/Zinc/Trivalent coatings) there is no need to apply a further anti seizure friction reducing compound, in engineering it is common practice to dry install, unless otherwise indicated!

And as all spark plug manufacturers advice to NOT install using Anti seize friction reducing compound.

All spark plugs fitted at the time of engine build, (OEM factory) are dry installed and torqued correctly.

When I get some spare time. I will show exactly the difference between a dry installed spark plug in an Aluminium cylinder head, VS the installation with Anti seize, I will use exactly the same applied torque force for both, and you will clearly see, the spark plug coated with anti seize, over torqued by approximately 20-30% of the initial applied torque loading.