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Would a failing chain tensioner disappear for the entire day until an overnight cool down?
As bad as yours sounds, I'd think it would make at least some noise on the next cold startup. Obviously, the longer sitting and the cold have an effect. Once warmed up and the oil has pumped into the system it should be fairly quiet. I'm trying to remember if our CCTs are oil filled along with the spring.
I'd listen to those VVTs carefully, though. How much rpms do you give the engine when you start it?
had a similar noise recently, disapeared after 1-2 min of engine idleling. turned out it was the corrugated egr pipe, located right rear in the compartment, beetween enginge and gearbox.
the pipe had a little fissure wich closed on its own while warming up.
you should be able to determine the failure by pulling and pushing the pipe by hand while the engine running, be aware of heater temperature.
if the sound changes during that procedure youv´e got the culprit.
fritz
No EGR on the NA XK8 US version. Like BobRoy keeps telling you, remove the serpentine belt to eliminate all the external components.
No EGR on the NA XK8 US version. Like BobRoy keeps telling you, remove the serpentine belt to eliminate all the external components.
+1 again. Don't go down the rabbit hole but keep it simple and methodical. Every eliminated possible problem is money not shotgunned.
I've had bearings go on serpentine and SC tensioner and belt pulleys on both of my cars; both with less than 100k on them. Sounds horrific; my XKR had the supercharger idler bearing go and it went from purring to snarling in no time flat.
If you start the car with the belt on and the noise is there, turn it off immediately, pull the belt and test each of the pulleys. Bearings are super cheap and pretty easy to install. Change the belt too, just good maintenance!
Well.... So far not so good.
Sound no longer only on cold overnight startup, but also after sitting a few hours.
Mechanic pulled belt and all pulleys seem fine.
Car was warm and quiet so I decided to leave overnight for them to hear on morning startup.
Mechanic is almost positive he's gonna deal with a timing chain tensioner issue.
Wants to hear it at its worst.
I'll know tomorrow
Looks reassuring. Had the full monty.
Not impossible, but hard to imagine 3rd gen tensioners failing after 10K.
Did you try the cold start with the serpentine off?
Mike
I left the car overnight at the mechanic.
I'm meeting with him in an hour and he's gonna do a cold start and go from there.
I told him to remove the belt prior to start and he agreed.
I'll update
As suggested, the car was started without the belt and it purred like the kitten it is.
Turned out that both the tensioner pulley and idler pulley both crapped out same time.
