govertime

Over the weekend I did some 60K mile maintenance on my car including changing my spark plugs and discovered the plug closest to the front had a pasty/creamy rust film on the plug and somewhat on the walls of the spark plug shaft (hole). The other 3 plugs were clean.

Any ideas of what might have caused this? Any performance or other concerns I should be aware of as a result of this?

Thanks for your input.

BTW the picture sucks cause it was taken with my phone.



edit: perhaps this is related to the spark plug shaft seal ??? https://mbworld.org/forums/c-class-w203/237454-oil-spark-plug-chambers.html

C230 Sport Coup

I looked at this the other day....
never seen anything like it...
but rust usually means water.
Water in the cylinder, very bad!

Pull your oil filler cap...
does it have a tan colored mayo looking substance on the bottom?
The rusty creamy stuff you describe sounds just like that.
If yes, your head gasket is blown...
or there's a crack in the head on the cylinder #1.

Are you loosing coolant?

I'd be inclined to want to get a look inside the cylinder,
find a mechanic with a boroscope I think it's called?
Fiber optic viewing device to see in there....

TruTaing

Couldnt this be a sign that he is also running rich? :x

GDawgC220

If you have the tan/cream looking stuff under your oil cap, usually means condensation. Do you have a lot of short drives?

Usually that stuff is a result of the oil not coming up to temperature to burn off the moisture/condensation. When condensation/moisture is mixed with oil, that tan/cream stuff is what gets produced. Bring the car out for longer drives at least a couple of times during the week and get that oil temp up.

C230 Sport Coup

Yeh, but in just one plug?
Sounds like a blown gasket or head.

GDawgC220

Check your oil and see if you see coolant in it. Thats a good sign of a HG blown or smoke coming out of your exhaust while driving.

Could also be the valve cover gasket.

govertime

Took it into the dealership, with the muck-covered spark plug in a baggy and all of your aforementioned suggestions nicely typed up for them.

Their response. - It's normal to have dirty/rusty plugs. We can't change them under warranty.

Me - A) What's goin on here is far from normal. Its only happening to one plug and its not just a light dusting of dirt. Its a thick creamy film. B) I don't want you change the plugs. I JUST CHANGED THEM. That's how I discovered this problem in the first place.

Their attitude toward service is first deny as much service as they can by assuming a offensive level of ignorance by the owner and then when that option isn't available or the customer is a "pain in the ***" actually providing service..

The guy never looked at the dirty plug, checked the coolant level, nor analyzed the oil. All this after the car being there for a day and a half and me having to leave work today to inform them what a competent technician needs to do. Anyway, at least its noted in their service note in case something happens later. I think its a result of my accident anyway with the radiator leaking.

This was repeated for the sensor cam wires BTW but I won't let them get away without replacing those.

I swear I need either a therapy session or shot and beer every time I come back from there. Serenity now.

mleskovar

Don't worry, it's on the outside of the plug. "I think its a result of my accident anyway with the radiator leaking." is the correct answer.

C230 Sport Coup

Get a compression and leak down test.
And maybe an oil analyses from blackstone labs.

If there's water in the oil, you'll know.
Sux that your dealer is so crappy.
Call MB headquarters in NJ, and tell them you want to talk to
the regional tech representative, that your dealer is not acting properly and you want to talk the tech rep. If you manage to get a name and ph #,
keep it in a safe place. I met the reg. tech guy here early on, and dropping a dime from time to time, got the dealer off their *****.

Don't mention any accident....just gives them an out, and not their responsibility.

mleskovar

Why is everyone thinking this may be coming from the oil? If oil was migrating up through the cylinder (broken/worn rings or worn valve guides), through the plug threads, you'd have a VERY fowled spark plug. Oil in the plug galley usually comes from a leaky galley seal and it doesn't burn off...but accumulates around the plug. What did the plug electrodes look like?

govertime

The electrode/tip looked like the others, nothing spectacular. Actually, from the threads down it looked fine. So it looked like it wherever the gunk came from was from top of the socket chamber.

What's the galley seal? Is it similar to spark plug shaft seal ??? https://mbworld.org/forums/showthread.php?t=237454

mleskovar

Yes, that's it. Run it for a bit and look at the new plug. If it's clean then the discoloration was probably from coolant that got in there when your radiator went.