I Sincerely Hope That I Am Not To Late & That Something Really-really Bad Has ALREADY Happened To You. Replace It!!!!!!!!(the Harmonic Balancer) I Have The Same Car 98 C280 . These Balancers Have A Factory Defect (time Bomb) Built Into Them . If Yours Was Shaking That Is Really Bad But You Can Tell If They Are Going By Looking Down On It As The Car Runs & It May Wobble Or If On Inspection You Notice The Rubber Buldging Out On It . I Didn't Believe It WhEn I Was Told Mine Was Bad But After Extensive Research I Found Out These Were Designed Or Built Defective. These Things Come Apart While Your Motor Is Running & You Can Guess The Results . Good Luck Al