It is a common domestic ritual to replace cap,rotor, and plug wires with that uniquely American term a "Tune-up".

Such maintenance is probably valuable with the POS equipment used on domestic iron. MB stuff has no predicted lifespan and I never change such parts as some routine maintenance. Properly tooled technicians can evaluate the components during normal servicing and make specific recommendations.

Defective caps and rotors can cause misfires, hard starting, and in some instances hesitations. A new cap will do nothing to performance unless it is in specific failure.

For those not properly equipted to evaluate the system and who never visit someone who is, they will have to base their maintenance concept on how many wasted dollars they will throw at poor running cars. The look of the inside of a distributor cap and rotor will scare most amateurs, but has very little to do with their capability.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician