Unusual Cause of Jaguar XJ Valve Train Noise on Startup
Vehicle: 2004 Jaguar XJ (X350), V8-4.2L, Automatic Transmission/Transaxle
Mileage: 142,548 miles
Problem: This vehicle had excessive noise coming from both valve covers for about 10 minutes during the morning start-up only.
Case Details: The technician noted that it sounded like the typical Jaguar second chain issue. Although the tensioners looked OK, because of the mileage, he changed them just to be on the safe side. The noise continued.
The technician also noticed a slight chirp from the fan belt. Upon closer inspection, he found the problem. The belt would slip slightly for about five minutes in the morning when it was cold, which would bang the tensioners back and forth, causing the noise to radiate through the block to the heads.
Confirmed Repair: The technician replaced the drive belt, tensioner and idler pulley. After the repair, no more noise emitted from the valve covers. Problem solved!
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