Hey everyone,

This has been plaguing me since I got the car two years ago. At that time I noticed this noise and the dealership told me it was injectors clicking, but I'm not even convinced they could pick out the sound I was describing. It has gotten worse over time, and I decided to buy a wired microphone and stick it under the hood to see if I could get a good recording of the noise. It worked!

Below, find a link to a video I created showcasing the noise. I've used some text to guide your listening, and during the middle portion of the video tried to indicate ***NOW*** with text when the sound I am talking about comes in and out.


The sound is very rattle-y and inconsistent. If I am in Neutral I can hear it at idle, when I press the throttle it goes away as the RPMs rise, but when the RPMs restabilize I hear the clicking again. When I then let off throttle, the noise goes away, until it reaches idle again and the noise returns. Additionally, you can hear it throughout driving and especially when alternating between coasting/throttle, as shown in the video.

Anyone have insight into this? As I noted in the headline, I am thinking maybe Injector or Fuel Pump noise, based on things I have read on this forum, and I want to point my mechanic in the right direction.

Thanks, Kevin

 

I'm 99% sure that is the sound of a worn supercharger coupler AKA torsion isolator.
My V6S had it from the get-go back in 2016 at 26,000 km and 2.8 years old, I (supposedly) had the factory warranty fix applied - replacement of the SC snout including the coupler which fits in the snout - but the rattle never really stopped and it is gradually getting worse/louder. In my case I have never been fully convinced that the dealership really did undertake the snout replacement.
Another symptom of a worn coupler, I would say pretty much a give-away, is a loud "clonk" from the top of the engine (ie where the coupler sits) on engine shut down. Not every time but much of the time, say one in three times, but it gradually becomes more frequent and louder. Do you have that "clonk"?

 

Thank you for the reply and background. I originally thought that was what was going on as well, and was even getting the 'clunk' you describe on occasion, so I recently had my shop replace the snout and coupler under extended warranty (I have Allstate, it has been wonderful for getting things fixed on the car).

So, I have a new snout, and new coupler, the shop showed me the old part and the old loose coupler. I have heard of others having had to replace more parts of the supercharger, but I'm not sure that's what this is. I have also read in other threads this car has a propensity for one of the two fuel pumps or an injector to develop this kind of clicking.

In any event I am taking it back in Wednesday to get it looked over. I plan to take the car to a track/autocross event later this month so I want to be sure that at bare minimum it's not something that's about to fail and brick the engine.

 

Thanks for the reply, which now has me thinking my rattle could be something other than the SC coupler, coz mine sounds exactly the same as yours!
For years now I have puzzled over what it could be, the coupler or one of the HP fuel pumps or the SC belt tensioner or the coolant pump etc, but more and more I became convinced it was the SC coupler again. Doubtful it is the SC belt tensioner as that was renewed just before the SC snout was replaced (misdiagnosed by the dealership).
I very much doubt it is one or more of the fuel injectors as that is much more of a tick than a rattle.
It could also be a rattling timing chain or tensioner (I hope not!) as they were a big problem on the early AJ133 V8 but were "fixed" with revised parts on the AJ126 when it first came out in 2012. Not completely fixed, they sometimes fail, but fairly rarely.
My main suspect is now the number 2 HP fuel pump, please let us know what the mechanic/tech finds.

 

Well I guess on the bright side, if you have had it for years, and so have I, it can't be that bad? (Yet, haha)

The tensioner is an interesting one, but you said it's belt drive? The reason this is interesting to me is I have an old 1972 Honda CB450, an air cooled 2 cylinder bike. When I first bought the car, this sound in particular immediately reminded me of what a loose timing chain tensioner sounds like on the moto engine.

One thing I THINK I noticed (but this could just be coincidence) was that the noise seemed to go away for a while after I got my oil changed. That gave me the idea that it could be an oil pressure issue somewhere in some little nook or cranny of the engine, however the noise doesn't go away in conditions where the oil pressure would be high, like under throttle, so maybe a blocked oil passage or something.

I'll let you know if my mechanics can figure anything out.

EDIT: Here is the fuel pump post I found, hard to hear the sound in the clip provided. https://www.ftypeforums.co.uk/viewtopic.php?t=6191

 

I'm talking about three separate tensioners, two on the engine timing chains (one each side and inside the timing chain cover) and one on the SC drive belt (external and visible down the front of the engine). They can all rattle although if a timing chain tensioner is shot then the timing chain will rattle so much it will usually drown out any rattle from the tensioner itself. Yes, good oil flow is critical to the operation of the timing chains and tensioners and any of the tiny oil passages being blocked by sludge etc can cause big problems, one reason why Jag specify 0W20 in these engines and also a good reason to change the oil at least twice as often as the ridiculously long specified interval of 12 months or 16k miles whichever comes first.

 

Long update here:

Step One - Independent Mechanic
I brought the car to my indie mechanic, they used my video to pinpoint the noise, and removed accessories/belts and isolated the noise the best they could to the timing chain area. They were unable to/not experienced with the internals of these engines so I made an appointment with the local Jag dealer.

Step Two - Orloff Jaguar in Chicago
Brought the car in for further inspection and they shooed me out the door without even inspecting. They told me the noise I was hearing was 'normal' for these engines, and that if it was bothering me I should replace the engine cover and delete the symposer. I wanted to believe the sound is normal, but I also really got the impression they just didn't want to take on the work. They couldn't tell me WHAT the noise was, only that it was normal, and explained that I would be disappointed if I had them just start replacing parts and it didn't improve. I really just want to know what the noise is, so I made an appointment at a different dealership.

Step Three - Jaguar of Hinsdale
Left the car with these guys and they came back to me with "FOUND VEHICLE MAKING NOISE WHEN COLD , REPLACE TAPPETS , VALVES, AND TIMING CHAINS" at a cost of $19,285.73. I let them know at this point that I had an extended warranty with Allstate, so my provider sent out an inspector who confirmed he heard the noise in question but explained Allstate needs 'proof' in order to agree to cover the repair.

What Next?
I'm not really sure what to do next. It'll cost me $5100 to teardown the engine to point of failure, and if it is proven the repair is necessary, Allstate will cover that amount plus the additional repair costs. If it cannot be proven the repair is neccesary, or Allstate declines for some reason, I'll be out that initial $5100, plus the same again with any gaskets etc that need to be replaced for reassembly. So it could end up costing me nothing if Allstate covers, or $12,000+ if they don't.

The service advisor told me the tech is "pretty confident that they will find the tappets are out of spec" and so the proof should be no problem, but they wouldn't let me talk to the tech, so I don't have total confidence they aren't just telling me that to get me to spend some money. I also haven't been able to get a straight answer on whether this is actually a problem with a potential for catastrophic failure, or if it is just a noisy engine and will be fine.

In the end, I have the warranty for another 14 months, at which point I'm gonna get rid of the car anyway. I'm leaning toward not doing this work to avoid having to pay this all out of pocket. The question then becomes: Do I drive it for another year or trade in for something else ASAP? My fear is that the noise will get worse over the next year, and then I'll have a harder time trading the car in.

Anyway, long post, don't really know what I am gonna do, but it seems like the noise, in the end, might be tappets.

 

Kinda confused??
These are DOHC engines. They don't have tappets? They run the cams directly on top of the valves and use shims to set the clearance. I have never heard of any of these engines to even need to have the valve clearances adjusted?

So not sure what they are talking about?
Have you removed the SC belt and started the car?

They do mention the attached TSB about the fuel pump noise so maybe it will help?
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I really find the dealership, and especially dealing with service advisors, to feel untrustworthy. I don't know enough about these engines to know whether they have tappets or not, but the word 'tappets' is used specifically in the notes provided by the tech. My previous indie mechanic removed the SC belt to rule that out, I have no idea if they tested the fuel pumps at the dealership tho.

 

Ok good. I just wanted you to do the simple stuff first like removing the SC belt.
Hopefully nothing going on with the valves but there is a chance I guess?
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I was looking through the AJ133 engine diagram and came across the section regarding 'tappets', which reminded me of this thread. It seems they do have tappets so maybe your dealership isn't as untrustworthy or not competent as you originally thought. Screenshot of the page from the manual.