Hi, As my previous post stated, I just bought a 98 C280 sport with about 135k on it. I like to do all of the maintenance myself, so that I can save some $$. however, the more i look over the car the more I find wrong with it. After a while I started to notice that the car developed a rough idle and a "tapping" noise which came from the engine compartment. I'm not used to working on mercedes, so I have some ideas, but no definite answers as to why my car does these things. Any help would be appreciated.

Thanks,
Christian

 

I believe your model and year were part of a lawsuit which resulted in Mercedes extending the engine warranty to 150K mi., provided engine damage was caused by sludge. Your model C (and latter) come with a maintaince feature called FSS. Essentially, the car only needs oil changes every 10K mi. provided you use 100% synthetic oil. (FSS lets you know when it's time) Well, someone forgot to tell the US dealers and oil changes were done with regular (organic) oil. Organic oil can't make it 10K mi w/o risking engine damage from excessive sludge. The warranty extention is available to all, not just original purchaser.
Something you should do right away is change the transmission oil. Yea, it's supposed to be good for life, however mechanics I talk with suggest changing it every 60K mi at the very least.
Also, the MAF is know to go bad on these cars and that might be the cause of your rough idle. How's your fuel mileage? S/b 21 city to 27 hwy. If it is much lower than those numbers, I'd also suspect the MAF

 

Christian, I also have a 94 C280 and had the rough idle problem, which was intermittent and only upon slow deceleration and at stoplights in "drive". The shaking would disappear in neutral. Open up the tapes/tubes that protect the engine wiring and note the conditions of the wires. Are they cracked/corroded? If so, you are the victim of the 'experimental' materials used between (I believe) 94-98 to coat the electrical wires, hence causing shorts and rough idles/misfires. Not good to keep driving like that as could eventually cause electrical fire. Some mechanics will offer to repair /tape up only the shorted wires; I opted for the entire harness to be replaced. Now my car runs like a dream (save the whirling issue I just posted about above).

 

hey guys, thanks a lot for the input. I think im going to take my car to a mechanic and have him do a once over... check all the fluids.. (replace trans. fluid) and see about that 150k warranty. Im going to also check the MAF and the plugs and wires. (possibly the entire harness).. Again, thank you for your input and thank you for the advice.

- Christian