Rudeney

I changed spark plugs on the CLK today. I only have 51K miles, but since it's 6 years old, it's actually a year beyond the schedule. Anyhow, the job was easy on the M273 - much easier than on the M112/M113 engines (not counting having to deal with fewer plugs). Below is a photo showing the old (MBZ NGK's) and the new (Bosch). If you look at the tip of the cathode, you'll see significant wear. Also, you can't see it, but the anode is significantly pitted. I compared the gaps from the old and new and not even counting the pits in the anode, it was at least a 50% larger gap on the old one from cathode degradation. So, basically, it was "time to replace them":

mis3

Do you feel any change of the car performance or gas economy?

Fatz

Which one is the old plug?

I have about the same mileage on mine. I think I'll put changing the plugs a bit higher on my list..... I haven't looked into how to change them. Is it pretty straightforward and did you change the wires as well?

Glyn M Ruck

No wires to change on the M272/273. They are coil on plug engines unlike the M112/113

The level of wear shown on the old plugs stresses the ignition system & can lead to coil failure.

Rudeney

I haven't driven enough to tell if there is any change in performance or economy, but I wasn't having any issues beforehand. I just changed them as I was doing my B-service and going through the list, I realized plugs are due the earlier of 5 years or 91K miles. The few miles I did drive last night on a 40mph highway made no difference. The only performance problem I ever experience is a little bit of engine chugging and lumbering when it's very hot out and sitting at idle. I won't know if the new plugs help with that until summer when it gets into the 90s.

Oh, and Fatz, the new plug is the one on the right!

mis3

I usually change my plugs every 60k miles for all my cars. I follow this schedule for a long time but I am not sure if this is still valid with the new technologies.

My current plugs were replaced on Mar-2011, some 34k miles before.

klonsbury

Funny, I did mine 2 days ago. I noticed the same "larger" gap on the older plugs. They were very worn. Have 85k and I'm not sure when they were done previously.

So far I've noticed slightly better throttle response.

Glyn M Ruck

I usually find that worn/fouled plugs give you slightly spluttery starts & that this goes completely with new plugs.

In ROW the plug change interval has settled at 100,000Km's or 4 years. Cars that are used for short trips & run their plugs outside the self cleaning range can shorten this substantially. My C240 needed new plugs at 45,000Km's ~ very much a town only car. You can't clean these plugs other than taking the car on a 1000 mile trip. Use of an old style grit blaster to clean them destroys them.

Yidney

Rodney, I'm changing mine this weekend. Does MB provide a torque spec on the plugs? I've change lots of plugs and use the "I know it when I feel it" approach, but thought I'd check. Also, I'm using Bosch YR7MPP33, and I assume they come pre-gapped, but what is the gap just so I can double check that.

Glyn M Ruck

M272/273 plug torque = 23 Nm/17 ft.-lbs Is usual guide.

Here is the rest.

Rudeney

And yes, the Bosch plugs come pre-gapped. Have fun!

mis3

I found this spark plug at fcpeuro. Is this the OE plug for 2004 CLK320?

Bosch FR8DPP33X12 $67US for 12 plugs.

Rudeney

According to the owner's manual:

Bosch F 8 DPER
Beru 14 FGH 8 DPUR X 2
NGK IFR 5 D 10
Gap: 0.039 in (1.0 mm)
Torque: 15 – 22 ft.lb (20 – 30 Nm)

mis3

Sorry. I am not familiar with spark plug codes at all.

When I googled "Bosch F 8 DPER", FR8DPP33 (the one in FCPEuro) came up. Is "F 8 DPER" a series of Bosch plugs which consists different plugs?

Rudeney

The "R" will just note that it is a "resistor" plug, so "F 8" and "FR8" are essentially the same. The rest of the numbers, I am not sure about. If the part supplier says this is the correct plug for the engine, then maybe it's just a revised part. When I put plug in my CLK550, I just bought what the guys at Advance Auto said were the "Bosch" plugs for my engine, and they looked identical to the ones that came out.

Louie D

I may do a change this weekend. Has anyone tried or heard any comments on the NGK Laser Platinum Spark Plugs (PLKR7A) The seem a tad more costly.

Yidney

This is interesting because every place I search for 550 plugs comes back with the Bosch Y7MPP33, which this chart says is for the 350. I have never seen a reference to the Bosch plug for the 550 recommended on this chart. Does it matter?

Yidney

And I also notice that the 350 and 550 plugs have different gaps on the chart. So if I buy the MPP33 plugs that now every store says is for a 550, and they are pre gapped for a 350, do I widen the gap?

Glyn M Ruck

What I have posted above is out of the international owner's manual. The recommended heat ranges are slightly different 350 to 550 + gap. To my knowledge the plugs all come pre gapped at 1.0mm.

I do not know whether you would notice the difference between the two plugs or the different gapping. I have to admit that I have always fitted Bosch plugs to friends M272 powered cars at pre gapped spec with no issues. My car only has 17K miles on the clock so I have not had to do a plug change yet. Dealers never regap new plugs.

Rudeney

THis is the plug I put in my CLK550. They were identical to what came out:

http://shop.advanceautoparts.com/web...sch_25964612-p

Glyn M Ruck

This is obviously a running change made by Benz with no explanation as usual.

What I posted is in the 2009 Operator's Manual:

Order no. 6515 1338 13 Part no. 209 584 44 97 Edition A 2009

And in the 2009 Maintenance Booklet:

Order no. 6515 8283 13 Part no. 204 584 22 93 Edition C 2009

My car was one of the last produced in 2009.

I would now love to know why Benz made the change for the 550 & not the 350. I'm going to try & find out from shear interest but I'm not very hopeful. As you know the Benz attitude tends to be do as your are told.

mis3

I went to Autohausaz and entered the MB part number (from an invoice of the last spark plug change in the dealership), the site returned with this plug: FR8DPP33 which is $7.35 each.

If I queried spark plug for 2004 CLK320, 4 results showed up and they are all a lot cheaper than FR8DPP33. One is actually written is an dated version but is cheer.

Looks like the website is suggesting different plugs than what my dealership uses (or used before). I am confused which one I should buy.

Glyn M Ruck

Rodney has given you the correct plugs for the M112 ~ 320. Here is what your handbook says.

Glyn M Ruck

By the way nothing wrong with using the R (resistor) version of the plug to suppress ignition noise from radio and other on board microprocessor electronics.

mis3

Below is from Autohausaz, this is what I should get, OE plugs.
The description says it replaces DPER and DPP33 but not sure it is the R version. It is $4.83 each.

I am also looking for spark plugs for my friend's 2003 CL500. According to Autohausaz, same spark plugs.

7422 Bosch OEM
Spark Plug; Platinum; Standard Electrode; OE Plug
12 per engine Updated version of OE spark plugs F8DPER, F8DPP33, and FR8DPP33. Pregapped for normal usage.