Hi guys, I am new to the forum and have owned quite a few cats of various models and years. I recently acquired a 04 xj8 and bought it as a slow project replacing and upgrading various parts. I noticed this cat has a nasty 2 second or so rattle on start up but once warmed up if you cut it out and restart it is lesser of a rattle or not at all. Has anyone heard of this or had experience with such an issue? Thanks in advance, Chris

 

It is helpful if you can provide the number of kilometres/miles the vehicle has travelled along with other details.

Has the oil been changed recently and is the correct specification being used along with the correct oil filter? Your post provides no location, so what is the ambient temperature in degrees Celsius or Fahrenheit?

 

Hi, 114,000 miles on her and it's had the rattle since I got her at 109,000. I noticed when the temp was very cold i.e. 32 f /0 c and below the rattle wasn't heard but as warmer days approached it was very loud and sounds awful for the 2-3 sec during initial start-up. I had the oil changed at 111,000 mobil 1 and a oem jaguar filter. Current temps range from mid 50's at night to low 80's during the day. Thanks

 

I've had this issue for 2 years now. If the car has been sitting for more than a few hours, I'll get a loud clatter for literally just 1 second. I've tried every weight of oil and every type of filter, but nothing has helped. After hours and hours of research, I came to the conclusion that it's a VVT issue.

Apparently, many engines with Variable Valve Timing develop this racket. It's common across all the brands, not just Jaguar. What happens is there's a little locking pin that holds the VVT gear or whatever it is in place when the engine shuts off. For whatever reason, this pin decides it doesn't want to lock in place any more, so that when you start the engine, the VVT gear goes nuts for second, which creates the rattle. If the oil hasn't drained out of the area yet, it won't make the noise. That's why it only occurs after the car has been sitting for a while.

Supposedly it is just noise and does not cause any additional wear or harm to the engine, unless it continues on for more than a second or two. It is fixable, but you would need to perform a bit of surgery on the engine to be able to replace the VVT gear.

 

Much appreciated, that makes sense. I had another xj8 that developed this rattle after sitting for awhile. I will investigate the cost and see if its feasible or not. Thanks, Chris