Rauhbatz

Managed to replace 3 out of 4 of my plugs last weekend...1991 190E 2.3 runs much better.

2nd plug from the back exhibits a binding feeling after loosening a few turns. I have been putting PB Blaster on the plug for the past 2 days and driving it...it feels like it is starting to loosen up but still binds after about 3 turns.

I seem to recollect rusted plugs will break loose and then turn easy...doubtful its rust as all of the other plugs came out pretty easy (including the one all the way back near the firewall).

Any thoughts welcome as it just leave it alone to avoid a heli-coil job or be brave and just do my best to remove it. Im concerned about the latter as I think these are aluminum heads.

Rauhbatz

Saw a technique on the internet to tighten, loosen, lube with penetrating oil (PB Blaster) several times. I did this over the course of a week.

Success! Tried extracting the plug tonight...had a lot less binding and then it loosened up a lot. Replaced with a new plug and turned the key.

Started right up, wonderful idle and no mis-fire off idle!

Ready for another 100K miles I think...500 km grill badge...here I come!