PeterLech

My E350 has 52K miles, but is past the 5 year interval for the recommended plug change.

It runs fine, and the recent smog check showed extremely low numbers. Mpg is consistent. I cannot see the reason for a plug change at this low mileage. Am I missing something?

(My Porsche 993 calls for a plug change at 60K miles, no time interval is cited.
At 16 years old, it continues to also have very low emission readings and consistent mpg numbers.)

N_Jay

Some worry about seizing in the head if not changed or at least, not R&Red at some reasonable interval

WEBSRFR

Same situation as you... My 2007 E550 is technically due for changing plugs but I only have about 45K miles. I researched this quite a bit and the consensus was with the really low miles I have, I can defer this until I reach about 7 years or so. That's what I intend to do as I barely put 6K miles on the car since I have a second car.

vettdvr

I changed mine at 85,000 miles and they still looked new. Not a problem removing. But when you do remove them. Don't crank them out. Break it loose then work it loose/tight easily each time moving out about 1/4 turn. This will break any carbon off and not damage the threads. I used a sparkplug antiseze and diaelectric grease on the plug caps.

PeterLech

Thanks for the input. Good tip about how to remove the carbon from the ends.

Doesn't the factory put anti-sieze on the plug threads when they are first installed?

Glad I found this site yesterday while searching for battery information. It seems far more comprehensive than other MBZ forums. Very useful for me, being a DIY type.

realeric

You don't need to change them at 50k miles unless you were stuck on traffic jams all the time. Manufacturer put the 5 year term for these peoples. Never use antiseize on spark plugs. It will cause misfire if contacted with the plug core, mislead torque reading, cause cracks, and result in extremely difficult removal.

PeterLech

My mistake, I forgot that about no anti seize on spark plug threads.

Plays havoc with catalytic converters also.

Long Islander

This is a timely post for me as well. We're coming up on 5 years, but only have around 30k miles. Sounds like I can put this off for at least another two years.

PuyW211E350

OK, that was the first time in my life I actually felt bummed out when I got to the last spark plug! What a sweet heart of an engine. I've only owned this car since March. And I can't stop driving it every chance I get... about 10k miles so far... 7k in 6 months is normal for me.

I spent more time looking for tools and finding decent songs on my ipod while doing this job, than I did doing the job!

I went online and ordered all the maintenance parts on Sunday night. I figured I'd install the parts as I received them. Much to my surprise, I got home Tuesday evening... there's an envelope on the doorstep. I was glad my oil filter arrived... but wait, it's the spark plugs... darn. But I heard it was an easy job (30 minutes to an hour, sure!). I watched the video on YouTube (the 1st half is for the 12 plug earlier models, the 2nd half is for the 6 plug cars), looked pretty straight forward.

I spent a lot of time messing around and it took just over an hour, maybe an hour and a half if I include putting the tools back up.

Tools: 5/8 Spark Plug socket, T30 Torx bit (Coil/Boot Assys), Torque wrench, Ratchet, various 3/8" extensions.

No real special items/tips to pass on. All intake and plastics bits come off as advertised. The Coil/Boot assemblies have a bit of suction derived vacuum behind it... a little slow pull and the assemble came off with a cool a little "Pop". I backed out each plug a 1/4 turn, tightened it, backed them out a little more, tightened, then loosened them all the way out... I used the by hand twist method (versus a ratchet) for the most part... installed them until seated by hand, then torqued them down. 23NMs equals 17 ft. lbs. of torque.

The plugs that came out (67,160 miles on the clock), looking perfectly tanned, with about what I expected as far as wear. Previous to the change, the engine had a slight rough idle to it (I'm very picky), but it is now sewing machine smooth.

As easy as this job was, and as inexpensive as the parts were, I'll probably do this every 30k from here on out.

vettdvr

Dang after 20 yrs of using antiseize I never knew it would cause misfire so I just kept using it and being able to remove plugs later without damage to the heads. All my vehicles use antiseize on the plugs except my diesel truck. However, I am very cautions to keep a very small amount on just the threads. Somehow I would suspect the very high temps from burning gasoline might just burn the antiseize off unless it was gobbed across the electrode. But doesn't it dissolve in gasoline and high velocity air?

N_Jay

A little was a requirement on Fiats or you could almost guarantee seized plugs.

It is always a compromise because lubricated threads need to be taken into account in torque specifications.

That is where TORQUE PLUS ANGLE method is much better than just a torque spec.

danskviking

Well, what type plugs are you putting into the 211? Old plugs are Y7MPP33 and are a little difficult to find outside MB.

PuyW211E350

The plugs in my car, with 67,160 miles, backed out cleanly.

The boot sure fits snug, creating a good seal in the plug "silo"... I under if that would trap any spin-off from burning anti-seize compounds? Anyhow, I read this post top to bottom first, and decided to follow the recommendations. We'll see how things go next time I have to replace the plugs.

Bosch YR7MPP33, which is exactly what came out. Ordered them online Sunday evening, they were waiting for me, on my doorstep, Tuesday afternoon... $44.52, after tax, title, and license... $54.07 delivered.

danskviking

So is the "R" as in resistor plug ok even if it is not called for?

PuyW211E350

Uh oh! OK, time to research!

Critter

Vettdvr, your comments are so right and have followed similar methods post 4.
As far as the others you can lead a horse to water but you can't make them drink.
Personally would never consider reinstalling a plug without Never Seize into a aluminum head and the dielectric grease on the coil boot is also a sign of someone who know his way around cars and not just a guy who has a few tools.
You will have to drop by on the AMG forum where now a days it seems like they all want to hack saw off the mufflers for weight savings, then complain its too loud???

biggking

Why let something as simple as $300 plugs ruin your engine? It's called preventative maintenance. On top of that expect throttle response to be better and for sure 1-3mpg increase. Your car will run more efficiently

vettdvr

A most gracious thank you. I have also noted the AMG forum. I think I forgot to mention the diaelectric grease but using it will prevent breaking the boot on the next plug change. Some horses just wont' drink until they pull the first plug and notice all the aluminum on the threads and wonder where did it come from.

Critter

LOL, so expensively true.

06E5004ME

Unless your spark plugs are completely worn out, any improvement in fuel economy is negligible. I changed the spark plugs on my previous cars when I didn't have to and saw no difference in before and after. With w211s, there are 2 plugs/cylinder, so it can get pretty expensive, especially on v8 engines. The only benefit I see in changing spark plugs is eliminating the possibility of seized plugs. Other than that, it's a waste of time and money.

Critter

A old friend of mine always stated /bragged how long the original plugs were in his car. The fact is that with the newer design coil on plug setup the plugs will generally run for a much longer time than normally stated but the coil does take some of the abuse when going down this path, causing greater operating temps for the coils. Well anyways he came to work one day and said that the car would not start and that the dealer had found the oil pan loaded with gas, when he continued to try to start the car the injectors were pumping raw fuel into the cylinders which in turn washed past the rings into the pan. After 60k miles what is a hundred or so dollars for plugs when you got a very expensive engine sitting in a very expensive car. Modern cars will basically run well until ------ then it's flat bed time!

06E5004ME

I'm not saying that you should never change the plugs, they are after all parts and parts break. However, I've yet to see a catastrophic spark plug failure that would result in something that bad on German cars. The plugs they come with from the factory are of good quality and should last for a long time unless you have other issues that would result in premature plug failure. Just visually check your plugs from time to time on each bank and decide then if you need to change them.

biggking

Not a waste of time. My plugs a 100k were DONE. TOASTED and it was a night and day difference. Its not a waste of time or money, its call WEAR AND TEAR. Like I said before why let a $200 spark plug ruin your engine.

Yes, lets just run our cars into the ground every time.. Screw oil changes screw spark plugs. I changed my coils and I can say that the E55 accelerates QUICKER and it puts me harder into the seat.

I worked with a dodge ram where the plug tip broke off into the engine, why? 244k and NO NEW PLUGS. I am not saying that everyone is going to run their car without changing plugs but yes **** does happen.

06E5004ME

biggking, I am not saying you are wrong, but in your example, the spark plugs lasted 240k+ miles, so in my opinion, you can easily expect at least 120k miles from
your original spark plugs. The original question was whether or not one should be concerned with replacing them after 5 years and I would argue that no, he or she should not. You can replace all of the engine parts in the name of preventative maintaince, but it would do you little good and will cost you a small fortune.

Critter

Well lets look at another way, MB is thinking the average driver logs 15-20k miles per year so at 75k-100k after a 5 year stint, yes it's not wasted money. I see some folks running batteries for 6-7-8 years and the wonder why the charging system is toast and all kinds on comments are on the dash readout. If you got a 5 year old Merc with 30k on the clock don't fret most people change cars at 5-7 years so chances are the next guy will get the pleasure of removing the plugs. Now air filters???