IYAAYAS, as for the water pump check for leakage from the weep hole. With the accessory belt removed turn the water pump pulley and check for excess play. If you need a replacement water pump recommend buying a reconditioned water pump from your local MB dealer.

Belt is usually measured in mm. The Parts Department at your local MB dealer may be able to tell you the proper length belt with the air pump removed, or you can do a Search on this website. The belt shouldn't turn at all by hand if it's the proper length and the tensioner is functioning properly.

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Fred Hoelzle