Your mounts(
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1YI003BTU1YI00CGX1&year=1997&make=MB&model=C-230-001&category=All&part=Engine+Mount )are the same design as are used on my 99 E300.
Measure the height of the mount from the outer rubber ring to the inner rubber ring at teh top of the mount. It should be at least 13mm. If less, they are colapasing and need replacement. A 13mm bolt head is easiest to use to measure as is usually too tight under there to read a tape. If you can see the top of the mount you can lift the engine 1/4" and then look to see if the top of the mount is cracked or separated.
If they are good do yourself a favor and look at the trans mount and then the flex disk and make certain IT doesnt have any cracks developing. You DONT want that to fail under use and have the drive shaft flail around at 60mph. Does nasty things to the undercarriage right under your rump.
