Board,
I have a 93 190E 2.6 L. I have changed the spark plug for cylinder # 3 three times in the past 4 months. The first time I replaced it I found out the ceramic on the Bosch platinum plug to be chipped.I think it got too hot. The second and third times after I got the original plugs from the dealer, both had a LOT of carbon build up bridging/filling the gap. Cleaned the plug with a wire brush and put back. The car drives Ok now!!However, I feel that it's running rich. The car hesitate when it starts in the morning for a second then idles fine. some times I get this on a hot start. I am thinking that injector # 3 is leaking! or the cold start valve is leaking, but why plug # 3 if the CSV is leaking. Any ideas!
Thank you all.
Abouzmm
PS. I avoid using gas with alcohol as much as I can.

Not running rich! This is a clear indication of worn valve guides!

You will need a valve job to correct this.
Good luck

__________________
Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS

Also possible to have a bad plug wire.
Swap it with another [ like #4] for a few miles and then see
how it looks.
If it is clean, look at the one you swapped with for carbon.

I find the plug wire theory tough to buy into. The good news is that it is easy to try as he describes, as long as the wire is long enough to reach.

Was the deposit that bridged the plug oily?

Good luck,

It happened to my 1965 Chevelet 350 engine 30 years ago. A bad spark plug wire caused the plug to have carbon build up bridging the gap and cross firing inside the distributor cap.

David

be459,

Okay, I see your reasoning now. I'll bet it was the cross firing itself that caused the bridge. I didn't make the correlation.

Thanks for sharing the experience.

Have a great day,

"You will need a valve job to correct this.
Good luck [/B][/QUOTE]"

I would think that before doing a valve job, a compression check would narrow down this possibility. If the compression check indicates no problem, then the intake valve seal on this cylinder would be a much cheaper suspect.

Steve

"

I would think that before doing a valve job, a compression check would narrow down this possibility. If the compression check indicates no problem, then the intake valve seal on this cylinder would be a much cheaper suspect.

Steve
[/B][/QUOTE]
The only thing a compression test will show is piston, bore, and valve "seat" condition. A compression test will tell you absolutely nothing about valve guide condition. The guide is on the wrong side of the combustion chamber. Remember that these cars will run fairly clean while using a lot of oil. If it's getting enough oil to leave heavy deposits on the plug, something is very wrong.
Randy D.