How often change distributor cap and rotor
 

how often should I change my distributor cap and rotor on my M103 for a W201?

yearly is a good idea, at least once every two years. You will save in gas milage and have better power. I change the plugs and cap and rotor at least once every two years for best performance and gas milage. Change the plig wires at least every 5 years. Just my opinion. Buy the inexpensive super Bosch plugs and they are super easy to change. DOnt spend lots of money on the platinum or +4 or irridium plugs. The w201 190E likes the proper factory plug and nothing fancy. They run great and only cost about $2 each

Perhaps every 50 to 100K miles
 

I had a 103 engine car in my E300 '87 that got to missing at about 90K and required a replacement of dist cap.

More recently, at 60K, (with no running troubles), I decided to check the dist. caps on a my '95 S-420. There was some dirty green tracking around the posts. I cleaned this off with laquer thinner and a strong bristled tooth brush. Once clean, I tried something that I had never heard mentioned here, (or any where else). And it seemed to work great -- I'm now at 113K and still having no troubles at all on the original caps and rotors.

What I did was spray on two coats of "Conformal Coating" of the type that is used on electronic circuits boards (computer motherboards, etc.). Its a clear very hard coating that has high die-electric properties. I'm hoping that it will hang in there a long time and stop the "arching over" that is the typical failure mode of these dist. caps.

The caps were kind of high cost to me so I thought that might avoid the need to replace.

What miles are other people getting on theirs ? I doubt it matters how you drive. Perhaps dusty conditions could affect it some ?

Luck to you,
DanielW

Sometime the tracking and build up inside the cap and on the rotor can be cleaned or made better, but the cap and rotor for the 190E cars if ordered on line is not too expensive and the car will run lost better, even if you only clean the inside of the cap. You will find all sorts of tracking and pitting and wear inside the cap and on the rotor when you check it. Even if you dont replace, clean, every 20-30 thousand minimum