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2000 MB
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Discussion Starter #1
Hi,

Is it advisable to change the plugs when engine is hot or cold ? Metal expands when hot, does it ? Second querry, do we need to adjust gap on plug or is it ok to live it as it is ? I got new ngk 7090, substituting an original bosch plug. Thanks in advance.:bowdown:
 

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2000 Mercedes E320
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137 Posts
reply to hot or cold

I just did mine a few weeks ago. Did with engine cold. I used the same ngk plugs that you have and they come pre-gapped at 39, but advise to check with a gapper. They are easier to change if you remove 3 coil packs at a time. This will give you more space to work with.

Good luck

Brent
 

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Discussion Starter #3
Thanks Brent1988. I still have to buy a smaller extension so it will fit the tight areas. I have already changed 3 plugs and felt really good. thanks again.
 

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I think I used 1 1/2" ext. it worked perfectly all the way around except for the last plug nearest drivers seat, I took it off and went shorter. Be careful of the sharp metal sheeting in this area.

I'm fairly new to the site but really appreciate the help that I've received. I look forward to learning more so I can do the basic maintenance on my 2000 E320. My next project is ATF change. I have read all the DIY's/stickys that I could find but I have a lot of questions, I think too many to ask.

You may want to check the gap on your old plugs and see how far off they are. Mine were 45, and I was told it may have been damage caused by a bad CAT that was recently replaced.

Good luck with the rest of the plugs. Take care.

Brent.
 

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'98 E320 Wagon (non 4matic)
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Hey mate!

ALWAYS change plugs when the engine is cold.

I do not know of a single engine that calls for it to be done when hot or warm.

Yes metal expands when hot thus making the plugs tighter.

Not to mention you will burn yourself on the engine if it is hot.

I used the NGK plugs. Ohlord has responded to several Plug posts with acceptable alternatives.

I found out the hard way that the gap is .39 (nevermind what my manual said). Check the gap. Ohlord discourages the use of anti-seize due to the possibility of getting the compound in the cylinder and causing shorts and MB also saying that it is not needed.

I for some reason can not allow myself to follow this advice and I choose to put some Anti-seize on there. I MAKE SURE that that there is none on the bottom 1/3 of the threads or so. I have done this and had no problems w/ plugs going on 20k miles now.

Also, torque to spec. Torque to spec. Torque to spec.

If you only remember one thing, torque to spec.
 

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'01-E320 & 02-ST2
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Ohlord discourages the use of anti-seize due to the possibility of getting the compound in the cylinder and causing shorts and MB also saying that it is not needed.

I for some reason can not allow myself to follow this advice and I choose to put some Anti-seize on there. I MAKE SURE that that there is none on the bottom 1/3 of the threads or so. I have done this and had no problems w/ plugs going on 20k miles now.

Also, torque to spec. Torque to spec. Torque to spec.

If you only remember one thing, torque to spec.
Curious that you stress repeatedly the importance of proper torque...and miss the critical reason not to use anti-seize in this context. Anti-seize will in fact MASK proper torque readings, so you won't be able to torque to spec. (FWIW, the danger you reference is with respect to oxygen sensors, not spark plugs.)

Modern plugs are coated to reduce seizing, which is why you don't NEED it. The ability to achieve proper torque spec is why you don't WANT it.

Take care and enjoy the ride,
Greg
 

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'98 E320 Wagon (non 4matic)
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Curious that you stress repeatedly the importance of proper torque...and miss the critical reason not to use anti-seize in this context. Anti-seize will in fact MASK proper torque readings, so you won't be able to torque to spec. (FWIW, the danger you reference is with respect to oxygen sensors, not spark plugs.)

Modern plugs are coated to reduce seizing, which is why you don't NEED it. The ability to achieve proper torque spec is why you don't WANT it.

Take care and enjoy the ride,
Greg
And Greg is much more experienced than I am! Listen to him. Srsly.
 

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^ I change mine yesterday, I do not use anti-seize, 'cause in DFW we do not have any corrosion. The manual said spec. is 180-264 in. lb. range, I torque it to 250 in.lb. (15-22 ft.lb), (20-30 Nm), in case the tools are not lining up in perfect 90 degree. Spark plug is made of steel at the threads, engine block is aluminum alloy, how in the world they will be seized, all you have to worry is the plugs are being over tighten and striped the block. As you can see the spec. range is very large, just torque it and done with it.
 

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2001 SLK 320(217K Miles), 2002 E320 Special Edition(183K Miles)
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3,466 Posts
+1 on the NO anti-seize. I've just replaced the plugs on my SLK 320 after 8 years and 11 months/ 101,000 miles. They still came out easily. Just torque the new plugs to 21 Ft/Lb.
BTW, the gaps on the old plugs was up to 45, but the car still ran fine and returned 28 MPG. The twin plugs really works. :D
 

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Discussion Starter #10
Hi all,

Finally, I am done with the plugs. It was made easier with Ohlords tool. Without it really, i will not be able to unplug the plugs. It was back breaking though and it took me the whole day. The hardest part was indeed the last one on the drivers side. I had a 3 in. extension but wish it was shorter in length and it would have shorten it an hour shorter.

How much do you guys think do we save whenever we do this diy on our cars particularly the plugs ?

Feels good . I feel rewarded again.
 

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I had a 3 in. extension but wish it was shorter in length and it would have shorten it an hour shorter.

How much do you guys think do we save whenever we do this diy on our cars particularly the plugs ?

Feels good . I feel rewarded again.
I've read of folks who paid $800 to have the plugs changed...and that was on the V6. So even if it took you the whole day pretend you paid yourself $100/hr.

I have a 1.5" extension that is one of the most valuable tools I own. $4 at Sears IIRC.

Ohlord chastises me for it whenever I mention it, but for the novice I still suggest at least considering doing the motor mounts with the plugs. Work on one side at a time and raise the engine 2-3 inches so it pivots on the other mount, you'd be AMAZED at how much extra room you get. Helped a friend do his that way, under 3 hours for both jobs, including having to R&R the compressor on the V6. Much easier than when I did mine (separately). Even if you don't change mounts it takes just a few minutes to pull the single lower mount bolt on one side and raise the engine.

Take care and enjoy the ride,
Greg
 

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2001 SLK 320(217K Miles), 2002 E320 Special Edition(183K Miles)
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Hi all,

I had a 3 in. extension but wish it was shorter in length and it would have shorten it an hour shorter.
I actually use several short ones and build it up to the correct length like Lego blocks. Even more important on by SLK320 than on the E-class, due to the smaller engine bay.
Using the short 1 inch extensions at the top, I can start of with a nice working length and then remove one extension if I get too close to the side of the engine bay as the plug moves out.
 

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^ I did order the pry tool, but can not wait to start the replacement job 'cause I have a CEL to fix.The b wire plugs were removed with a mid shift loop wire wrap around the metal shield and a vis-grip to pull. There is another plug wire pier shown on e bay under S G motorsport. It has a shape of the metal shield at the point and the ends is designed like a pier. I wish I have a 4 inch extension. But I only get a 3 & 5, I did put a universal on the 3 to make a 4 inch. But the universal was broke when I was removing the 3rd plug from the driver side.
 

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2000 MB
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Discussion Starter #14
Hi again,

I think this job was the hardest one for me. I used to own japanese cars and they were a breeze with 4 cyl. or 6, and the numbers of plugs needed to be change was either 4 or 6 plugs. With the mb, it's like working on a 16 cylinder automobile. No wonder I felt sore at the end of the day, but then again, it was a rewarding job to do . Thanks again to all the people here who contributes their expertise in the name of fellowship.
 
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