Simple Huh.. Someone has been there before and left me problems. I removed all the plugs and numbered them. In a inspection I noticed that two of the plugs had not been seated by about 3/16 to 1/4" short of bottoming out. They were also platium plugs. Maybe that was part of my roght idle problem. On one of the plugs I had to use a brake over long handle to get it out. All the time I was sure it would seize the next revolution. It came out okay. I used a thread chaeser to clean out all the plug holes and coated the new plugs with anti-seize.

My question or any comments please. How do you tell that you are bottomed out in the plug hold ?. If the holes are gummy with gasoline varnish the torque get high and I am not shure I am there. Is this a common occuranct on Alum. heads. This is my first Gasoline MB I have been a Diesel guy for 30 years. I also used copper core plugs and my idle is better.

Please give me any shop secrets on simple plug replacement..

Thanks All.

H. O. Tyler
1990 560 SEL 130K
1985 300 SD 62K
1983 140 D 260K

One of the secrets is not leaving the plugs in for 5-6 years. Even on low mileage cars the plugs should be removed & replaced every 2 years or so. Cleaning the threads is always a good idea if plugs come out hard or if in too long. Correct heat range is important.