It is over that time that I need a "tune up" on my 90 300 SEL. I usually spend 1-2 hundred dollars and let my mechanic do it, but if I can get the parts on this site and it is not that difficult, I thought that maybe that I can do it.

The engine is starting to run a little rougher than usual, thsi is the first sign that I need a tune up from my experience with gas engines typically. Usually after around 20,000 miles and it is at least that by now. I thought that I would first change the spark plugs, but when I tried, it did not look that easy, looked like there was some special clip on them. What do you need to take them out? What plug should I replace them with? The ones on this website?

Also will that do the trick or is there other stuff that I should check/replace after 20,000 miles. Change oil every 3,000.

Thanks




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'89 420 SEL
'90 300 SEL
'84 300 SD (sold it)

Oooo! Ya pressed the wrong button. Most modern techs cringe at the word "Tune-up".

That term originally refered to the art of adjusting a piece of equiptment for optimum performance. It still does amongst the those who add chips, exhaust, and engine mods. But! There is nothing to tune about your car with the exception of the alignment.

Every item adjustable to tuners twenty years ago is tuned multiple times a second by the cars engine management system.

As to what maintenance your car's engine would need; I would suggest plugs, and filters. Plugs are simple on most MBs and a 300 is no exception. The only problem is getting the plug wires off. They just pull off (yuk-yuk). We use special pliers that grab the metal connector at the base. Even then many connectors get broken. They also are easily replacable.

Unfortunately proper maintenance involves a competent technician assesssing many items that the new systems are managing. Cap and rotor used to be routine; now they are both expensive and take some labor. Evaluating ignition using an engine analyzer keeps problems away and avoids shotgunning these parts.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

When I saw that someone had answered this question, I hoped that it was Steve or Doc. I couldn't agree more with what Steve said.

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Benzmac:
Donnie Drummonds
1991 GMC Syclone
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM