Spark Plug Change

[500ESpain]

Hi,

I'm planning to replace the spark plugs and I think it's an easy job but I thought i'd ask before I mess it up. Is there a special precaution or trick I need to know?

Any recommendations on type or brand?

Torque settings?

Thanks

 

[gerryvz]

My recommendation is to use the standard Bosch plugs that are specified for the car. Don't use anything fancy such as the Bosch Platinum plugs as these are unnecessary and not worth the extra money. I think NGK also makes a plug that is up to the specs for the car.

Unscrew the tips from the tops of the plugs if they come with them (usually they do) as these are not needed. A "wobbly" socket is helpful to provide a better angle for some of the harder to reach plugs.

The most important thing is to be extremely careful when you remove and then REPLACE the new plugs so as not to cross-thread the new plugs into the soft aluminum heads. Tighten by hand (or with the socket placed over the top of the plug) as much as you can and DO NOT FORCE it -- if it doesn't turn by hand, then back it out, realign and try again.

As a tip, I always brush a little anti-seize paste (or motor oil will work in a pinch) on the threads of the new spark plug before inserting it into the cylinder head.

Check the conditions of your wires carefully. If they appear old, cracked or brittle, I'd consider replacing them. If you do so, use ONLY factory wires for the best fit. You will pay a bit more, but it will be worth it.

Hope this helps.

Cheers,
Gerry

 

[gsxr]

I had been using a Craftsman spark plug socket, which has a rubber insert to retain the plug. However, the socket would frequently "stick" to the plug, and my extension would pop out of the socket. It would always be a real nuisance to extract the socket.

While I'm sure there are cheaper solutions, the factory Hazet tool (shown below) works absolutely fantastic. The extension is permanently attached to the socket so there's never any problem removing it.

Part number 119-589-02-09-00, dealer cost $43, typical price is $50-$60 USD depending on where you buy your dealer tools.

 

[Glen]

It's not a hard job but the rear plugs are more difficult due to the tight space. Other than that, just take your time and it should go smoothly. Torque the plugs to 21 ft. lbs.

 

[500ESpain]

Thanks, guys. Very helpful!

 

[chappardababbar]

I asked a Merc mechanic about this procedure and he said that he always sprayed WD40 into each socket for a split second burst, before screwing in the new plug.

I can't remember what the reason was but WD40 is conductor of electricity so maybe it helps the spark?

Or maybe just to lubricate the screwing action (lol sorry).

 

[arno]

a word to the wise, be gentle with the wires. dont ask me how i know...

 

[gerryvz]

WD-40 is a penetrant and protectant (WD = water displacement) not a lubricant. Seems kind of moot to use it AFTER the plugs are removed.

As I said, I'd go with motor oil (a lubricant) or anti-seize paste (lubricant, which also makes eventual removal easier).

Cheers,
Gerry

 

[gsxr]

I believe WD-40 is not electrically conductive - can't find that in their FAQ's though. It does have lubricating properties but it's primary function isn't lubrication. According to the website, it "cleans, displaces moisture, penetrates, lubricates, and protects."

http://www.wd-40.com/faqs/

I would not use motor oil on the plug threads. A *small* amount of anti-seize should be adequate. Don't over-tighten the plugs - they do not need to be very tight! Just a bit beyond "snug" is perfectly fine. And, don't use a torque wrench if you have applied anti-seize. The torque spec is for clean, dry threads only.

 

[gerryvz]

I believe WD-40 is not electrically conductive - can't find that in their FAQ's though. It does have lubricating properties but it's primary function isn't lubrication. According to the website, it "cleans, displaces moisture, penetrates, lubricates, and protects."

Those are marketing claims! I know WD-40 has billed itself as a lubricant for many years -- heck, all of us used to swear by it on our bike chains and skateboard bearings when we were young -- and yes it does provide some lubricity in terms of stopping squeaks and such. However, I liken WD-40 MUCH more like Boeshield than I do to a pure, traditional lubricant.

It's not a lubricant in the same vein that silicon grease, Tri-Flow, LPS or other purpose-built lubricants are -- even plain old household or motor oil -- which tend to be much longer-lasting and remain where you put them.

There's nothing wrong with putting a few drops of oil on spark plug threads to help ease them into the heads - better oil (or as we both said anti-seize paste) than dry, bare threads. And oil is certainly compatible with the application

Cheers,
Gerry

 

[gsxr]

It's not a lubricant in the same vein that silicon grease, Tri-Flow, LPS or other purpose-built lubricants are -- even plain old household or motor oil -- which tend to be much longer-lasting and remain where you put them.

I agree 100%. WD-40 is more of a "temporary" lubricant. My favorite use is as an adhesive remover, it also works great to remove rubber bits from the painted rear bumper after a day at the dragstrip.

There's nothing wrong with putting a few drops of oil on spark plug threads to help ease them into the heads - better oil (or as we both said anti-seize paste) than dry, bare threads. And oil is certainly compatible with the application.

I personally don't use engine oil on spark plug threads. The high heat in that area quickly fries the oil into varnish.

 

[gerryvz]

The high heat in that area quickly fries the oil into varnish.

You sure got that right ! I've got an engine that's solidly coated with sludge on the inside and varnish all over the outside (particularly near the oilpan) from being in close contact with all that motor oil. It's made me wonder time and time again why they even specify motor oil being within a country mile of any sort of internal combustion motor.

Perhaps filling the engine with WD-40 would be a better solution. After all, it cleans, lubricates, protects and stops squeaks !!! I'll stop at AutoZone on my way home to get a case ....

Cheers,
Gerry

 

[gsxr]

Just make sure you do it right! The proper ratio is 4 cans WD-40 mixed with 4 bottles motor oil, with a dash of Slick-50 for good measure, topped off with Marvel Mystery Oil.

I should have said localized high heat; i.e. directly at the top / center of the combustion chamber, basically the hottest part of the entire engine. The lubrication circuit is designed to channel liquid oil around moving parts (bearings, camshaft, etc). The engine oil doesn't normally get locked into fixed areas for extended periods, i.e. on spark plug threads. All I know is that I've seen some plug threads with a dark brown varnish that almost acted like Loc-Tite, apparently from previous techs who put oil on the threads. I've never seen a problem when using anti-seize; but read post #29 below for more info on that.

FWIW, the FSM does not specify to apply anything to spark plug threads.

 

[Prime]

An alternative to the special tool shown above is a little electrical tape to hold the socket to your extension.

 

[500ESpain]

Thanks for the advice.

I think I'll use olive oil, we have plenty of that here in Spain.

 

[gerryvz]

I think I'll use olive oil, we have plenty of that here in Spain.

That's an excellent choice, but MB specifications require extra-virgin only -- no cheap stuff.

I've heard that cava works, as well (from the Catalan area).

Cheers
Gerry

 

[500ESpain]

:lol:

 

[gerryvz]

 

[500ESpain]

It's like an accident, you know you shouldn't look but you can't take your eyes out off it.

 

[500ESpain]

Hi, guys

Sorry, but I need your help again. I thought I wasn't able to mess it up in such a simple job but I did.

The reason for changing the wires was a small trembling from the engine when hot. Previous owner told me that he already replaced caps and rotors but not the wires so I thought that would be the next easy step to fix the problem.

After changing the plugs and wires and double checking everything, it was time to start but to my surprise the engine now trembles constantly from start.

I don?t know what I've done wrong or what I am missing so, please, HELP

 

[Trae]

Alright,

Novice mechanic here has to ask this question.

I have done many spark plug changes in my M119s and M104, and I forgot to unscrew the caps at the top of the spark plugs.

It was on the M117 that I was compelled to unscrew the caps to get the boots to securely set to the plugs.

Should I, now, remove said plugs from the M119 and M104 cars and unscrew the caps?

All cars are running great.

 

[gerryvz]

I always remove the screw-on caps from plugs I install on my MBs ... always have.

 

[Klink]

Should I, now, remove said plugs from the M119 and M104 cars and unscrew the caps?

All cars are running great.

No. Always look inside the plug wire boot to see if you have the small or the large terminal socket inside. Generally, with original factory components the M104 and M119 use the caps, while the M116/117 do not. Some replacement wire sets deviate from this, so again, the "rule" is to look inside the connectors and see which version you have. You can even have them mixed on the same engine if some aftermarket wire ends were individually fitted...

 

[Klink]

That's an excellent choice, but MB specifications require extra-virgin only

Cheers
Gerry

Sheesh, You try finding an extra virgin around here...

 

[Trae]

I did NOT remove the caps on my first M117 change and the boot would not fit.

So, I unscrewed the caps the they seat very well.

The M104 and M119 boots also "seated" very well and a snug fit at the bottom.

I'll leave everything alone, because I believe the only boots I have that REQUIRE the removal of the caps is the M117.

 

[QuintBenz]

1994 E420 - M119

Recommended tool to remove spark plug wire where Orange Component of Part # 0356351053 is missing ?


[ Note: Driver Side boots easy to remove; Passenger Side boots absolutely will NOT budge. ]

 

[alabbasi]

I put Bosch plugs in my 1998 SL500. I was going to use NGK but seeing as the Bosch supers were available. I figured I would. It transformed the car which must have been on its original plugs. I used anti seize on the threads so that they would come out easily when I change them next.

A regular plug socket from my took kit worked just fine to get them out.

Zipping them back on is quick work with a 1/2 to 3/8 reducer and my dewalt air impact wrench (kidding... seriously I'm kidding)

 

[gerryvz]

You’ll need all of that anti-seize to get them back off again after torquing them on with that impact wrench !

 

[gsxr]

1994 E420 - M119 - Recommended tool to remove spark plug wire where Orange Component of Part # 0356351053 is missing ?

[ Note: Driver Side boots easy to remove; Passenger Side boots absolutely will NOT budge. ]

If the orange plastic broke off, I don't know what to recommend other than very long needle-nose pliers? I'm not sure if there are any special tools designed for this situation.

I put Bosch plugs in my 1998 SL500. I was going to use NGK but seeing as the Bosch supers were available. I figured I would. It transformed the car which must have been on its original plugs. I used anti seize on the threads so that they would come out easily when I change them next.

Don't use anti-seize. The plug threads are already plated to prevent seizing in aluminum heads. See attached PDF.

FWIW, the FSM does not specify to apply anything to spark plug threads.

 

[emerydc8]

I would not use motor oil on the plug threads. A *small* amount of anti-seize should be adequate. Dont over-tighten the plugs - they do not need to be very tight! Just a bit beyond snug is perfectly fine. And, dont use a torque wrench if you have applied anti-seize. The torque spec is for clean, dry threads only.

Hi Dave,

Are you still holding to this opinion on the torque wrench? Its been so long since I changed plugs that I forgot the torque setting, but the 21 nm figure sounds familiar. I'm planning to use anti-seize.

The WIS specifies 25-30 nm. Was this revised at some point? I'm presuming my plug is "with gasket"?

 

[gsxr]

Dave, Are you still holding to this opinion on the torque wrench? Its been so long since I changed plugs that I forgot the torque setting, but the 21 nm figure sounds familiar. Im planning to use anti-seize.

The WIS specifies 25-30 nm. Was this revised at some point? Im presuming my plug is with gasket?

Jon, the spec of 25-30 Nm is accurate, but is only valid for dry threads. I do not use anti-seize and always install new plugs dry (and, gapped to 1.0-1.1mm). See the PDF attached to post #29 above. And yes, the M119 plugs are the gasket type.

From memory, with dry threads and ~25 Nm setting on the torque wench, there's roughly 1/2 turn from first contact of the gasket to the wrench clicking, with NEW plugs. After the gasket is compressed the first time, subsequent installations will have much less rotation to achieve the same torque value.

If you do use anti-seize, use as little as possible (super thin coating). If not using a torque wrench, use your calibrated arm to feel when the gasket has compressed (not easy if you aren't Klink). If using a torque wrench, I would cut the torque spec in half, set your wrench for 12-15 Nm. Be careful with anti-seize! You really don't want stripped threads. I've never seen a plug seized in an M119 and would recommend to skip the anti-seize and install try, to factory torque spec.

 

[TerryA]

Jon, the spec of 25-30 Nm is accurate, but is only valid for dry threads. I do not use anti-seize and always install new plugs dry (and, gapped to 1.0-1.1mm). See the PDF attached to post #29 above. And yes, the M119 plugs are the gasket type.

From memory, with dry threads and ~25 Nm setting on the torque wench, theres roughly 1/2 turn from first contact of the gasket to the wrench clicking, with NEW plugs. After the gasket is compressed the first time, subsequent installations will have much less rotation to achieve the same torque value.

If you do use anti-seize, use as little as possible (super thin coating). If not using a torque wrench, use your calibrated arm to feel when the gasket has compressed (not easy if you arent Klink). If using a torque wrench, I would cut the torque spec in half, set your wrench for 12-15 Nm. Be careful with anti-seize! You really dont want stripped threads. Ive never seen a plug seized in an M119 and would recommend to skip the anti-seize and install try, to factory torque spec.

When I changed my plugs for the first and only time my 500E the old plugs were in so tight I was afraid of stripping out the threads. I couldn’t believe it.

When I put in the new set I did use anti-seize but I have never torqued in spark plugs. Only hand tightened and used 3/8” driver for final tighten until it’s snug. That’s it!

 

[oaklandw124]

While Im sure there are cheaper solutions, the factory Hazet tool (shown below) works absolutely fantastic. The extension is permanently attached to the socket so theres never any problem removing it.

Part number 119-589-02-09-00, dealer cost $43, typical price is $50-$60 USD depending on where you buy your dealer tools.

Anyone have one of these for sale?

 

[JC220]

I second Gixers advice on avoiding the use of anti seize. It's not required and I agree the potential for false torque readings and / or thread damage outweighs any benefit of using same.

 

[emerydc8]

Thanks, Dave. I'll have to calibrate my arm for this one! That's good information on the 1/2 turn after gasket contact.

 

[emerydc8]

I just got these Bosch (Made in Russia) plugs and noticed the installation diagram on the side. What is the significance of 90 degrees? Is that how far to turn it after the sealing ring grabs (perhaps a modified @gsxr technique)? The torque they list is 28 nm.

 

[oaklandw124]

I had been using a Craftsman spark plug socket, which has a rubber insert to retain the plug. However, the socket would frequently stick to the plug, and my extension would pop out of the socket. It would always be a real nuisance to extract the socket.

While Im sure there are cheaper solutions, the factory Hazet tool (shown below) works absolutely fantastic. The extension is permanently attached to the socket so theres never any problem removing it.

Part number 119-589-02-09-00, dealer cost $43, typical price is $50-$60 USD depending on where you buy your dealer tools.

Still looking to add one of these to my tool collection if anyone has one they want to sell.

Thanks, Eric

 

[gsxr]

Still looking to add one of these to my tool collection if anyone has one they want to sell.

These are still available new from MB, spendy at $67 (Napsterville link below), but reaaallly nice quality:

Spark Plug Wrench 119-589-02-09-00 | MB OEM Parts

119-589-02-09-00 - Spark Plug Wrench

www.mboemparts.com

119-589-02-09-00 - Spark Plug Wrench MB Parts Source

Factory Direct Spark Plug Wrench (119589020900) For Your

www.mbpartsource.com

 

[oaklandw124]

Thanks, Dave. My local dealer says no stock anywhere but I will reach out to these two places today and see if they have them.

 

[gsxr]

Thanks, Dave. My local dealer says no stock anywhere but I will reach out to these two places today and see if they have them.

Shoot! I wonder if it's a temporary OOS, or if it's impending NLA.

There may be an aftermarket equivalent from Hazet, without the MB Star logo, but I've never researched this.

 

[oaklandw124]

Just spoke with MBpart source. None in Germany but was not listed as NLA.

I sent a message to Hazet to see if they can source. If so, I will let the board know.

 

[luckymike]

I use this Craftsman locking extension.

The Stahlwille locking universals are pretty handy, too.