[W126 Coupe] Fouled Spark Plug

[Josh Allen]

On 9/1/2010 2:24 PM, Henry Viveiros wrote:

>

> My 1991 560 SEC had been running rough and the dealership diagnosed 

> the problem as a #4 fouled plug that may be caused by a valve seal. 

> They cleaned the plug and things seem to be OK. Is the #4 plug on the 

> right or left side?

>

> My question is: can I remove the spark plug and clean it every once in 

> a while---I'm really not into taking the engine apart to replace the 

> valve seals.

>

> When I look at the spark plugs I can just see the tip of the top and 

> not the part that the socket would fit on. Can I just slip a socket 

> onto the plug to determine the correct size to use? I haven't been 

> able to "feel" if I am actually on the plug or not. Am I likely to 

> cause any problems (breaking the plug)? I don't want to cause any more 

> problems than I already have.

>

>



If I remember correctly, it was the larger of the two common plug socket 
sizes, and I see no reason you'd damage the plug, as long as you're 
reasonably careful about not just jamming it in there and pushing some more!

As to cylinder numbering, on the M117 engine, cylinders 1-4 are the 
right bank, front to rear, with 4-6 on the left bank, front to rear.

http://www.autotrend.us/firingorder126.JPG

-Josh
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