The 1998 E320 has a V-6 engine(M112) & doesn't have head gasket problems like the M104 engine did.
Only real problem with that engine is the crankshaft Damper comming apart. List price on that is $70. & takes less than 3 hrs to install.
Check the auto trans 722.6. IT does need service.
MERCEDES Benz Master Guild Technician (6 TIMES)
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190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)