Hi all,

My XK 2006 and just back from its service (100k) and since, I have noticed that sometimes when it starts in the morning, i get a fairly loud clacking sound. Sounds metallic and makes it 3-5 times then stops. I usually don't have time to walk around the car get a clearer sense of where it comes from. If i restart the car in the day it doesn't seem to do it.
Car has not been used much last year but other than some wear and tear advisories (like tires and break pads...) the service hasn't highlighted anything else.
I have a "check pedestrian system" warning that comes up from time to time (so I assume one of the sensors reaching end of life). Don't think its related but mention it just in case.
Any idea what it could be?

Thanks

 

I believe that the variable cam mechanism which is bolted to the front of the cam cover might be a likely suspect on these engines when the engine is cold. Start the engine with your hand on the mechanism and you might feel it.

Richard

 

The VVT pin is whats doing it. My 2008 Rover with the same AJV8 started making the racket over 3 years ago and still has been doing it ever single morning. The repair is expensive so I havent bothered. I dont think that theres any danger if it falling apart or causing any engine damage. A cheap fix is to install an oil pressure system that fills the crankcase with oil before you start the car. But I havent done that either. My mechanic doesnt seem to be too worried about it either.

 

Get it checked yesterday !! if there's. slack in the timing chains you'll be doing alot of further damage to the engine

 

4.2L doesnt have timing chain issues. Its the VVT pin

 

According to who ? Lol

I've done chains/tensioners yes on the " industructable " revised 4.2 unit

 

First off I agree with you saying to get it checked yesterday. Im just saying its not his chains. Its usually the VVT, in the 4.2, especially when it gets cold. Now if the VVT is going bad, replace it. Which in case, yes, throw in new chains and tensioners, since youre already in there. But there are plenty of documented threads regarding VVT rattle on the 4.2, and its not doom and gloom. Some people have had success in making it quiet again, but I personally have not had any success with the Rover, so it continues to predictably do it on an old truck, although Im planning on replacing the solenoid as my last attempt before I say screw it, lets do it all. As for the XK, the OP should place his hand over the right cam cover and have someone start the car. The tapping will be apparent.

 

Thanks for all your comments.
I have tried to record the sound this morning (as mentioned would be better to have someone starting the car and the boot open but still you can hear the sound):

Also, no engine warning and no DTCs according to my reader.

 

As I said previously, get someone to start the car whilst you hold your hand against the VVT mechanism on the cam cover. It should be obvious if it's from there,

Richard

 

Yep, thats the VVT. Try replacing your oil first, then try the solenoid, but its not a death rattle. The chains and tensioners are not directly connected to the VVT cam. Its all oil pressure actuated so the solenoid could be the cause. Other than that, Ive been living with that issue for 3 years on my Rover, and all is well.

 

Thanks. The oil has just been replaced as the car just went a full service...
I seem to recall on other threads people using an additive to fix a VVT issue, is there such thing?

 

Nope, no additives will help. Ive done oil treatments, flushes and good ole Italian tune ups. Id replace the solenoid since thats what controls the oil pressure and flow. Im going to do that myself. Be sure your service tech used a factory filter and the correct oil too.

 

Probably not the VVT. Its the main belt riding up one of the pulleys and jumping back causing the tensioner to make that noise. Change it for genuine Jaguar deep grooved belt.

https://youtube.com/shorts/7THSNlGe7Xg?feature=share

 

 

My STR had VVT rattle.

I cured it by adding a bottle of oil cleaner and flusher to the oil. Over several days, I started the car in the mornings for a few seconds getting the flushing fluid up into the VVT unit and letting it drain back down to the sump.
Then drained oil and filled with new oil.
its never rattled since.

 

Not thread related but, what does "STR" stand for? Kinda new to the whole Jaguar scene.😏

 

Had to google it - Jag S Type R (guessing supercharged)

 

I've never seen anything like that before. I don't see how it's possible unless a belt has been fitted with one less groove as several of the pulleys including the alternator and the replacement spec idler pulley have raised ridges at either side. How could be belt ride over those ridges unless the tensioner was completely shot, in which case the squealing would be the most obvious symptom. The belt is available with an alternative number of ridges.

The Jaguar belt is a standard Dayco and is the same as the Gates and as far as I can see.

Richard

 

👍LOL! Guess i could have done that! Senior moment i guess!😂🤣

 

Correct. It has the same 4.2 s/c engine as the XKR. Its a beast.