Two problems related to engine knocking noise have been reported for the 1996 Ford Windstar. The most recently reported issues are listed below.
For approximately 2 months I noticed loss of compression during acceleration and occasional knocking sound from back of engine. Without tearing engine apart it seemed that the head gasket failed and allowed fluids into the engine. Confirmed rod bearing failed at 94,000 miles. Car was not drivable now.
Timing cover seal was leaking, upon having this problem fixed, the engine began making a knocking noise, engine was replaced.