The aux water pump is designed to run for upto 10 minutes every time the car is shut off, but you aren't supposed to HEAR it. Should be Quiet.
THE key problem on 1998 TRUCKS has been a source of 2 different service campaigns. Make sure that this truck has the latest version AAM modification, which includes all new keys!! & the computer that controls the locking system.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator