Hello there. My 03 XK8 (4.2) apparently has the classic VVT noise symptoms: slight valve rattle when cold with light or no load - goes away around 1500 rpm. It's not really that bad, but I'd like to see if I can quiet it down.

I've seen more than a few forum posts here where a member says he had a good outcome by flushing the motor with a temporarily lighter oil mixture that includes a quart of ATF. So, I'm going to try it.

I'm going to do an oil change with mixture of 7 quarts 5W-20 (lighter oil) and 1 quart of ATF. Afterwards, I'll drain and refill with my normal Castrol 5W-30 (synthetic). I may repeat this procedure a second time as needed.

However, I've seen a wide range of recommendations around the web on flushing any automobile motor with ATF. I've seen everything from a cautious 30 minutes at idle (no revving), to driving the car for 1000 miles. Others seem to insist on not using ATF and using Engine Restore product.

So, my question(s) are:
1. In what manner and how long should the motor be run with the flushing mixture?
2. I'm wondering if flushing with a regular motor oil in the mixture might be sufficient since I'll be draining it in short order?
3. Has anyone had a good outcome quieting the VVT with Engine Restore?

Ideally, I'd like to hear from those with direct experience with flushing the 4.2 engine to successfully address the VVT noise issue. Thanks!

 

Brutal's opinion would prove to be valuable in this thread. Hopefully he will see it and offer his experience for your benefit. Good luck, and let us know your outcome....

 

Synthetic oil alone is an excellent cleaner. Unless you have seen a seriously gummed up upper end by removing a valve cover I would suggest that VVT noise is due to wear rather than needing cleaning. A heavier weight oil or an oil thickening product such as Restore is the normal prescribed solution.

 

Yes, I've always run clean synthetic oil, and having owned a shop (25 years ago), I tend to agree that additives are generally unnecessary as motor oils already have them.

However, this car only had 50k on it when I bought it 2 1/2 years ago. It only has 65k miles on it now, so, excessive wear seems unlikely to me. (The car belonged to an elderly couple.)

Thanks for your input.

- Mike

 

"My 03 XK8 (4.2) apparently has the classic VVT noise symptoms: slight valve rattle when cold with light or no load - goes away around 1500 rpm."


Does the rattle go away at 1500, but return if idle drops below 1500? I ask because my impression of VVT noise is that it only lasts a second or two and goes away once the adjusters are pressurized with oil, regardless of RPM. Sure it's not the tensioners?

 

So it's not really been run enough - and who knows what viscosity oil or how often it was changed... Try some ATF for 500 miles then change oil.

 

I only hear this (mild) rattle when it's cold and under light load around 1200-1500 rpm. I read that an 03 4.2 will have the improved chain tensioners that are less prone to failure.

 

Yes, the member named abonano has confirmed to me that he used a lighter oil change (0w-20) that includes a quart of ATF. He ran this mixture for 700 miles and it helped him with a similar issue. Brutal, you and some others discussed this in this thread:
https://www.jaguarforums.com/forum/s...bad-vvt-68687/