bumparker

Car has just over 61k miles and is due for a spark plug change. I've had the plugs on the shelf for several weeks, waiting to get motivated and warm weather. Today was the day, I was motivated after a successful front brake pad replacement completed yesterday afternoon. So let me start by saying it is possible to change the plugs without removing the intake manifold, I don't know if it saves time but it is possible.

I followed a very detailed pdf (there are links in several threads) where a guy did the plug change on the same engine in his SLK without removing the intake. Since I had the same engine I expected I could do it too.

The passenger side is easy once you remove the air filter box (clic pliers to release the clamp). You have to really pull hard on the COPs to get them to release. Make sure to torque the plugs to 17 ft/lbs.

The driver side is a bear. There was a difference in the design of the brackets on my car vs. the SLK and it took me an extra hour to figure out how to remove the bracket. Once the bracket was removed the plugs were accessible and easy to change.

Total time was 3.5 hours and I did not rush, took several breaks. Cost for my materials was about $70 for the Bosch plugs, $15 for clic pliers (Amazon), $15 for star socket set (Amazon), I already had a good torque wrench. People say the dealer charges about $800 for a plug change.

I'm not recommending this as an easy job, I would say it is moderately difficult and you need a good set of tools. But it can be done it you have some experience and confidence.

I found very little information on the internet regarding the 2014 E350 sedan as related to plugs, brakes, shocks and struts. I'm figuring it out as I go.

Next, Bilstein shocks and struts are on the way.

Jabberwock

so after doing this with the intake on, do you feel it was worth leaving it on? whats the downside to removal?

bumparker

Based on what I've read about removing the intake, there are a lot of hoses that need to be disconnected, throttle body controls, etc. And you have to replace the gaskets/seals on the intake runners. I've read some of the connections are back by the firewall and hard to get to. One person reported they had a throttle body malfunction light afterwards. So it might be 6 of one and half dozen of the other on which way to go. I felt more comfortable not removing the intake..so I went that direction.

Touringman

bumparker, can you share with the collective what the spark plug part number and brand was for this engine. My Wife's 2014 E350 4matic is coming up on it's 60K service. Several notes I have seen say there was a production change on the plugs in 2014 and to compare with whats in the car before purchase. Additionally, other notes say that this engine requires indexing plugs, can you confirm if that is the case?
Thanks in advance!

bumparker

I used the Bosch Iridium plugs, the number on the box zr6sii3320, the box also shows the torque spec of 23nm of 17 ft/lb. The plugs are identical to the ones I removed. The plugs index by using the torque spec, they have a special one use washer that indexes the plug at 17 ft lb of torque. I was careful to torque the plugs because of this.

bumparker

Here is the pdf file that was helpful, the steps are basically the same but the brackets on the driver side of the engine are different from the SLK.

Jabberwock

wow that's scary... does it instruct on the thread cleanliness?

bumparker

No, but what I've read said not to apply anything to the treads of the new plugs as they come with a factory coating. The plugs all treaded in easily, I put them in by hand initially. The plugs are really thin and I forgot to mention you need a special thin wall spark plug socket

bumparker

tread = thread

raja777m

https://www.ebay.com/itm/Mercedes-Be...item1a4ef61963

or a 10-pack from amazon:


Are these ebay ones safe to buy? Do you think we can get them for a cheaper price?
I'm at 62k and talking to my SA about bringing my own spark plugs.