Hey there!,
I have an 05 xj8L with the 4.2 engine,112k miles. The other day upon starting it made a terrible noise that sounded to me like the timing chain slapping around, definitely top end noise, it only lasted a second but then started a fairly loud ticking that sounded like a diesel. I shut it down almost immediately and started to do some research. Is my engine cooked? Bent valves? There was no warning signs or hint that it wouldn’t continue running as usual. Totally out of the blue!
Today I removed the valve cover to investigate and found nothing majorly alarming but I’m unsure exactly what I’m looking for. Is there a way to test the VVT system or primary chain tensioners? The secondary chain tensioners don’t look worn or damaged but 1 side I am able to push up and down(springy) and the other seems to be set in the down position. Which is correct?
Anyway I’m a new member here and any insight would be greatly appreciated

 

I'm sorry I'm not much help! But these 4.2 are normally bullet proof to an extent. Very uncommon for timing chain issues at that mileage? May I ask what your oil change intervals have been?

It could be something else I'm guessing. Timing chain just doesn't sound right.

 

I haven’t had the car very long, but I’ve changed the oil every 5k with full synthetic, I’m supposedly the third owner but didn’t verify, the guy I bought it from told me he got it used from the dealership with a little less than 40k miles, I got it at 99k. Never seemed to smoke or burn oil, but the day it made that bad noise it made a bit of grey smoke(not blue tinted like oil burn). Thanks for the reply, any suggestions would be considered as I’m kinda out of ideas

 

Might try starting, then look around, to see if you can spot, just where the noise originates from.

 

I strongly suspect that what you are hearing is the locking pin in your Variable Valve Timing trying to engage. This lock uses oil pressure to engage (as does your VVT) and as your engine ages, it can tend to lose that oil pressure overnight?

Mine has had this 'Death Rattle' since I bought it some 4 years ago!

 

Thanks everyone!,
I have the valve covers off now so I don’t think starting it is really feasible but I did go out and buy a bore scope this morning to inspect the primary chain guides. From what I can see all is still intact.
this “death rattle”, has it not effected your driving of the vehicle? It seems to have a big solenoid in front of the vvt thing(not sure of the proper name) so I was under the impression it was electronically controlled. Is it caused by a hydraulic blockage, or bypass(worn parts)? Is there a way to clean or flush it? Anyone used Sea foam?
Anyway “death rattle” is an appropriate name, I’d have rather found a rattlesnake

 

Would unplugging the VVT solenoid make the sound go away, but loose a bit of performance as if it was a pre VVT engine?

 

The VVT unit has to be suspect. These things have a pin that is supposed to engage and stop the thing moving until oil pressure has built up. Over time, I suspect the thing just can't move due to oil deposits.

 

I do realise your comment is humorous, but would you have rather have found a timing chain or tensioner to be the problem? Remove your radiator etc and the entire front of your engine (including things you reaay do not want to be disturbing...unless you really have to)?
I have decided to live with it for the past 4 years and it does not sound any worse today than it did then?
Alternative is to replace the VVT system?
Your decision!!

 

Yeah, just joking, definitely preferable to timing chain/tensioners failure.
do you know of any way to repair or rebuild the vvt hub? Are the right and left bank identical parts? I imagine to remove them would be most of the way to doing a whole timing job. Would a heavier or lighter weight oil help or hurt the situation?
i certainly appreciate being able to learn from your experience. I think my answer for now is to just put it back together with fresh oil and sea foam before the next change. That may help to clear any buildup.

 

I really do think just live with it for the time being? Concern yourself with all the other issues which offer themselves with owning this aging classic car?
I am surprised that this 'Death Rattle' does not appear to have been more commonplace on this Forum? Have other Members experienced this?
I have read posts about it in the past (I cannot recall exactly where I read them), including one Member who went to extraordinary lengths to solve it; he fitted a tank which held pressurised oil which was then fed back into the system at start-up?

An ingenious German guy is all I recall?

I am sure that this 'Rattle' is not a good thing, but all I can say is I have always had it and it does not seem any worse 30,000 km later?

 

Wonder if an oil additive of some sort, might dissolve some of the sludge?

 

Hello Wingrider, I hope you are well.
I don't think the problem is sludge. I think It is that as our cars engines age and wear, they become unable to retain oil pressure in the VVT unit overnight and so the pin fails to lock until the oil pressure has been restored.
It only takes a few seconds to do so, but until it does there is this horrible rattle.
Do you have this rattle at start-up?

 

the secondaries can sometimes collapse and make a ton of noise. some cars have noisy phasers but if it’s really loud you might have a problem.

worst case just throw a used cam in it and replace the o-rings on the housing.

 

Not really 100% resolved but I’m moving on with my life. Dropped the oil pan for additional inspection and found nothing. I’ve got it all back together and am convinced it’s caused by the vvt hubs lacking oil pressure on startup. With fresh oil/filter it made no noise and ran as smooth as ever. After a little more reading I’m starting to think that the anti drain back valve within my old cheap filter my have failed or never existed(not totally sure if they all have it). I don’t necessarily believe this caused the problem(likely just wear since this seems to be a fairly common problem) just exaggerated it. If(probably when) the noise comes back I’ll report mileage to the forum, but I don’t plan on taking any further action. Thanks everyone for the help and easing my panic