How do these M112 spark plugs look?
 

I have a large oil leak that started a few weeks ago, so I am doing the CLK320's valve cover gasket, breather covers, spark plugs and vacuum hoses.

Do these spark plugs look fine? I assume they are original since they haven't been updated to the new style that I got in the mail. Car has 142k.

Is it just me or does the spark plug gap look big? I'm new to the M112 engine though, so I have no prior experience with this engine at all.
(Heck I made the mistake of just ordering 6 plugs...I only found out that it needed 12 right now!)

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Measure the gap. I forget the spec .04"? They look like they've had a few miles - might as well replace before they seize in the threads.

Those do not look like the correct spark plugs. The correct plugs for the M112/M113 are platinum and have a very small center electrode.

they are wrong and worn out. when the center looks like a well worn pencil, it's time.

the correct plugs are fr8dpp33 and have a much finer electrode. usually about 10 ea usd. which is why the wrong plugs are there-cheaper. the real plugs will go 60k or more. i don't like to go to 100k like mb says to do because the coils and wires get tired from the extra amperage required for older, worn plugs. good luck, chuck.

It says on a few sites that the F8DPER is the original plug. The updated is the FR8DPP33 with the small electrode.
That is why I thought maybe these were the original plugs.

They are definitely getting replaced though! I felt like the car was robbed a little power.
Either way these plugs have way more than 60k on them. We've owned the car for 40k...and the PO I find doubtful changed them right before, so I figure they have 100k on them.

i've changed a bunch of these engine's plugs and don't remember seeing those come out-could be wrong.

i also can't believe 142k on them. replaced any coils and wires over the years? just curious. i have a few times when the fr8dp33s wore out before 100k. let me know, chuck.

No history...so not sure. They are expensive I just looked it up so what are the typical symptoms when they are toast?

Our normal daily driving says average 28.1mpg so I assume they are fine?

I've seen worse, 50 K is a likely mileage.

One plug will have a worn center where the other will have a worn strap. This is due to current flow, a system like this should fire one plug in one direction and the other in the opposite direction. ( Unless this system uses an AC inverter for spark power but I doubt it.)

Who sells the plugs at a deal?

I have to change them on W210...

Thanks,

Martin

I get my plugs thru ebay

The original plugs I pulled from my bro's car with 136k on them were the fine very small electrode type.

Gotcha, so they have been replaced at some point with cheaper ones. I did some research and it seems that they are the same performance-wise, they just don't last as long.

I sure as heck don't want to do this every 60k...I'll take 100k for a few bucks more.

Engine looks clean, pulled one side off today.

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Left side all done minus the coils! Off to school, then hoping I can get the right side done later tonight. Even the breather tubes were pretty clean. The breather hole wasn't too clogged up either, but it did need a good shot with the air compressor to clear it out 100%.

Second photo is the breather before I cleaned it. Not bad in comparison to some of the pictures I've seen on this forum!! I'm pretty sure this has never been replaced either. There is no way otherwise they would have been FORCED to replace the vacuum hoses. They just crumbled in my hand.

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if the car needed coils, you'd know it-misfire, check engine light, etc.

as far as 100k-like i said, mb says they'll go 100k, but i've had earlier mileages where the coils were suffering from overdrawn amperage because of the worn fr8dpp33s. change them at 60k and there won't be any coil or wires issues. got 2 cars with almost 200k ea and they have oe coils. 3rd set of plugs though and another set due at 240k, if i see either of them again. good luck, chuck.

that is a nice n clean engine, using mobil1 0w40?

my car also had these plugs when I swapped them out due to irritating misfires at part load. I used denso plugs (platinum tips and centers), cost me 2 dollars a piece after discount at AAP.

what did you seal the breathers with?

Only wanted to say....
 

....enjoy your posts ps2cho......keep'em coming.....

I am using Reinzosin sealant. Some posts say its the same stuff MB uses, some don't. Can't get a consensus, but it should be fine. I believe the application is half the battle.

0-40 Mobil1 has been used, or at least by myself since 100k miles.

When buying the spark plugs, don't use any platinum, resistor or nothing like that. They burn rich, decrease fuel economy and cause crappy idle and misfires. Been there done that. Beru has some good plugs for these cars I love. Beru 14 F-8 DPURX02

synthetic really cleans the engines sweetly.

The best engine sealant I found is toyota FIPG or the AC delco engine sealant which GM uses now, I also found that the tube dispenser tool is a very nice item to apply the sealant in the crevice.

when I sealed my cars breather covers I used the caulking tube of AC delco sealant in a dispenser and it went very quickly and very evenly - The sealant sets in half hour. I also bought the toothpaste tube dispenser tool where you can stick the tube in it and squeeze the handles to get a very good control on applying the sealant. I found it on a GM TSB.

The AC delco and toyota sealant are extremely robust. Infact I know of some indy shops that use them on all german and british engines.

Yeh my Reinzosin sealant comes with the toothpaste metal tool and it made applying it a breeze. At first I didn't know what it was, but then it made sense. I don't know how I ever used sealant without it before!!

this is the tool I bought - its great

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I usually buy this sealant - as its easy and cheaper to get and you can stick it in your caulking gun tool. specially useful when applying it on toyota engine timing chain cases

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Although it does not look like it the M-B sealant will fit in a standard caulking gun. That's how I use it.

the loctite 5900 which is MB sealant comes in a full size caulking gun tube also, its about 90 dollars from fastenal or less from amazon etc.

I think you can do more than two engines with it. - I prefer the GM one, its easier to get and sets quickly once the parts are assembled compared to other products where you wait a day and this 1/3 caulk tube is about 20 dollars

Finished up today. Drivers side looked just as clean.

While I was in there, I got around to doing the idler pulley and the fuel filter. I then disconnected the battery and inserted the key to make sure no residual power was present. Connected everything back up and on 2nd attempt to start it fired up and ran perfect.

However...I think the engine mounts are toast. I visually inspected them and they didn't look collapsed at all by any stretch, but while driving I noticed at idle that the steering wheel is shaking. Do you think this indicates both need to be replaced?

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