Replaced Clutch 1 Day later Knocking sound and Oil Everywere on 1995 Saab 900

Had the Clutch replaced drove it from the shop 20 miles later it is leaking oil everywere. It know makes a knocking sould or like something is raddeling around.

Asked by for the 1995 Saab 900
Sounds like rear engine seal failed at rear of crankshaft. Either is the old one and may have been damaged during clutch replacement or was replaced and failed from either defective seal or poor replacement procedure. If enough oil leaks out then engine components that need oil will cause noises. Bearings, lifters, etc.