Hello all,


Doing a full-blown major tune-up plus new ignition coil on my 1986 560SEL this week and have run into a bit of a snag – the spark-plug on no.8 cylinder fought me all the way out despite using generous amounts of penetrating oil.


Thank goodness no threads came out and a visual inspection of the bore with a dental mirror and flashlight reveals no visible thread damage. Spark-plug threads perfect.


The only indicator that something might be amiss is a slightly higher amount of gray aluminum powder + oil gunk on the threads near the crush washer.


To the point – which is the14mm reverse thread chaser should I use to clean things up a bit before proceeding further bearing in mind that no.8 is a tight one in terms of accessibility?


Your opinions & experiences would be GREATLY appreciated!


Cheers!