[W126 Coupe] Fouled Spark Plug

[Camran Nassiri]

Hi Chet- would you recommend a little anti- seize lubricant before you screw the plug in to make it easier when the next time you are removing the plug?

Thanks,
Camran
91 420SEL, 80 240D


 


From: chwilka at comcast.net
To: mbcoupes at mbcoupes.com
Date: Thu, 2 Sep 2010 07:17:34 -0400
Subject: Re: [W126 Coupe] Fouled Spark Plug








Pick up a “spark plug” socket from your local auto parts store.   It has a rubber sleeve inside that holds the plug in so you don’t drop is as you’re removing it.  There are basically only 2 sizes, large and small (I think ¾ & 5/8 inch). You want the large one.  You may also need a few extensions and a swivel for you ratchet, some plugs are hard to get to.
Take your time removing the plug and if it becomes harder to remove as you’re unscrewing, stop and screw it back in a bit and then go back to unscrewing.  Repeat until you get it out.  The threads sometimes get gunked up and you don’t wanted to force anything and possibly strip the threads in the head.  The plug is steel and head is aluminum.  When you reinstall, clean the thread and hand screw the plug in and just snug it up with the ratchet.  Do not over tighten or you may strip the head.  And never use power tools on spark plugs.
Depending on the mileage, you probably have a worn valve guide not just the seal.
 
Chet
 
  
 




From: mbcoupes-bounces at mbcoupes.com [mailto:mbcoupes-bounces at mbcoupes.com] On Behalf Of Henry Viveiros
Sent: Wednesday, September 01, 2010 5:24 PM
To: 'Mercedes Coupes Mailing Lists'
Subject: [W126 Coupe] Fouled Spark Plug
 
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.
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