1999 Other Jaguar Models chain slap

I have been offered a 3.0 V6 S-Type Jaguar. It is a 1999-2000 and the price is £600 (my uncle is offering it to me at a family pice) The car has covered 137,000 miles and at the startup there is a slapping noise coming from the timing chain cover of the left bank (usually only for a few seconds, somtimes up to a minute). Many Jaguar forums talki of an uprated cam-chain tensioner, as the seals fail and cause a loose cam chain, my biggest fear is that it may be the big end shells causing a loss of pressure to the top end, or even the oil pump itself. Can you tell me if the cam-chain tensioners are a common fault on the 3.0 V6 and if not, what usually is. Thank you for your time. Paul