I've been doing some searching and haven't been able to find any information specifically relevant to my engine (2009 Jaguar XF Supercharged, so it's the Supercharged 4.2L), so I thought I'd post the question here.

Since I received my car back from the shop for warranty work, I've been experiencing a fairly loud rattle on startup. It lasts a second, maybe 2, then goes back to being its perfect, silky smooth self. Power doesn't seem to be down in any way, no new vibrations or anything that I can determine. No check engine light, nothing to indicate anything is wrong.

Since I'd just received it back from the shop, I assumed they'd moved a heat shield or something while investigating a whistle that I'd reported while they were changing out the seat heaters under extended warranty. After a few weeks, I finally put it up on the lift, took the covers off and went looking for a heat shield touching. Didn't find anything, but I did find a broken piece of aluminum, and a cracked passenger side motor mount. Finding the mounts were about $200, I decided it was worth the hour drive back to the dealer to have them replace the mount under extended warranty, and let them diagnose the rattle.

I got a call 4 days later with an estimate of more than $20k in parts alone, that said I needed to replace the engine because the oil was low. There was no low oil light, and no check engine light, and the engine runs beautifully, but they said it had damaged crank to rod clearance. I've since picked it up from them, because after discussing how they determined it and why it would require a new engine as opposed to just replacement bearings, it was clear they hadn't actually checked to see if there was damage to the engine.

I've searched around online and I find an almost identical set of symptoms for the earlier 4.0L engines related to secondary tensioners, but I haven't found anything or anyone reporting the same issues on the 4.2L engines at all, or the supercharged version in my car.

So my question - does the 4.2L Supercharged engine in these cars have the same secondary timing adjusters that are prone to failure? Because the symptoms are pretty much identical to what I'm experiencing. My FIRST thought (from other engines) was that it sounded like hydraulic lifters leaking down, because as soon as oil pressure comes up, the sound is gone.

Any thoughts?

 

No the 4.2L has rock solid 3rd generation tensioners. Jaguar also upgraded the chain on the 4.2L. My 2005 STR is at 115K and is very quiet still. Not really anyone posting problems with the 4.2L Tensioners. SC or NA.

I have been under the car a good bit and it looks pretty easy to drop the sheet metal oil pan and take a look?

I would tell the dealer to do that but they should have done it anyway. That is a giant repair bill and I would also like a rock solid diagnosis before I did anything.

And with a DOHC engine you don't have lifters anymore.

Now if the engine was run low on oil the noise could be from a lot of places because of wear. Maybe a cam follower ticking, maybe the valve stem wore down. Hard to say.

Could you do a quick oil analysis to check for metal? Might help give you an answer.

Where did the broken chunk of AL. come from?
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Why wasn't the low oil diagnosed by the dealer when they had the car? Why no low oil warnings?

 

If it's a bearing issue typically the car is quiet on start up and starts ticking after the oil thins out. Also, you generally need to pull the crank out and have it polished if you have a bearing issue. If you don't polish the crank the new bearing will likely fail very soon after.

 

Dropping the pan is on my to-do list - luckily I have a lift in my garage at home, so I was going to pull the underbody trays and see if it's possible to remove the pan without having to lift the engine.

I definitely agree with the fact that they should have done it first, you don't throw a new engine at a problem until you're sure what the problem is. My issue and a big deciding factor of taking my car away from them is that at this point they have a vested interested in finding bad bearings, so if they were bad at this point I'd always wonder if they did it on purpose just to prove themselves right, so I need to see for myself.

 

On the service writeup, they said the car had about 2 quarts of oil in it. From searching around on the Internet, it seems as though the XF low oil warning is calibrated to come on under 2 quarts. So as I explained to the dealer, it seems that in the opinion of Jaguar engineers, my car did not have low oil, or they'd probably have to recall and address the issue with all the Jaguars with 4.2L engines.

 

What I'm seeing that has me hopeful is some posts regarding the VVT solenoids leaking down and not keeping oil on the later 4.2L cars as well, which could also explain the noise. Like I said (comparing to hydraulic lifters, which aren't found in OHC cars) it sounds like there's slack in the valvetrain until the oil pressure comes up and then it's perfect.

I may take a look at this first. The thing is, it's all still covered by extended warranty, so parts aren't a concern, I just need to verify what's wrong so I don't get charged $20k for a new engine just to replace a $200 part.

 

Update - laid a long screwdriver against the solenoid connector and listened to it at startup, and there's a loud rattle on the Passenger side, and quite a bit less on the driver's side (probably hearing it telegraphed from the Passenger side.)

Basically I'm having to wait 3 or 4 hours between tests to get it to rattle at all though, which sure sounds like an issue with oil pressure leaking down to me.

 

This is a problem we have seen a lot in these cars when the oil change interval is stretched even a little or oil level falls for an extended period. Especially when using the shitty Castrol that Jags marketing department recommends.


As you suspected it is timing chain noise from the tensioners leaking down. That is why it goes away quickly when pressure comes up. Rod knock, as you probably know, is a different animal altogether.


IMHO if the noise lasts only a second or two then goes away then how much damage are you really doing? How many high end cars do the same even when all is correct?

 

Interesting about the VVT because the Jaguar V-6 engines have a lot of VVT problems.
But it should set a VVT code?

Don't think that's the problem because the 4.2L NA has always had VVT from the beginning and we don't get any reports of VVT issues.

Now the 4.2L SC did not get VVT until 2006 and up so less time and fewer cars involved.

The tensions are just not reported as problems or as making noise either.

Hope you get the real answer and let us know too! Maybe replace the VVT but I think they are pretty expensive.
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That's ridiculous. The engine takes more than 6 quarts when full. There's no way they can check the "crank to rod" clearances without pulling the engine. You need a new dealer.

Bad crank bearings knock like crazy. A heavy rhythmic knock that gets worse as the oil warms up. Piston pin bearings tap with a quick double tap sound. Main bearings rumble.

Rattles from a supercharged engine should be diagnosed carefully. For example the Eaton supercharger uses a plastic coupler in the nose to dampen vibration. These can wear and when they do they rattle.

These engines to not typically use oil. Also, Castrol makes some if the best oil in the business and anyone suggesting otherwise doesn't know what he's talking about.

 

Update to this: Took it to a local European Auto specialist here, and when I described the symptoms, before I told them my suspicions they said "That sounds like secondary timing tensioners to me"

Working with Jaguar/Land Rover extended warranty has been painful, because they have to come inspect the damage parts and approve the repairs before they can proceed, and based on how long it takes to inspect them, he either has to swim over from England or at least walk from Florida, where the company is based.

But teardown and inspection confirmed the secondary timing tensioners were toasted, so to be careful they're replacing both sides and the oil pump as well. The shop I used also caught the cracked motor mount (that I forgot to tell them about) and some bad control arm bushings (that I didn't know about myself.) So I'm impressed with the shop so far, but haven't actually gotten the car back yet.

I agree though, when I was searching I didn't find any reports/posts regarding the same issues on the XF Supercharged, HOWEVER, the Previous model XKR uses the same 4.2L Supercharged engines, so when I expanded my search to those, I started to turn some up, and the symptoms described were identical to what I was seeing. As to not throwing a code, it's not the actual actuators themselves that fail, it's a seal in the bottom of the valve that leaks down when it sits for 2-3 hours (or overnight). So the system still technically functions as it should when the car is on, but it takes a second to regain pressure when it starts. For reference, I think I priced the secondary tensioner setup at around $220, but you'll have to remove the timing covers on the front of the engine to get there, so it'll be a bit of a job to do, but doable for a home mechanic.

So it could be that most XF owners aren't enthusiasts who post their problems on websites to help others diagnose their cars, or possibly I just got a bad set, but it was definitely confirmed that they were bad.

 

Glad you got a diag. I was going to add that you are hearing the noise at the VVTs because that's right by the secondary tensioners.


It's not a bad fix, we've done 3 or 4. At least your timing gear will be nice and tight from here on out. ;-)

 

Wow I'm having the same issue with my '09 SC XF. I took mine to the dealer they said I needed an oil change after that I'm still having the same issue. So at least it looks like someone found out what is really the problem.

 

Richter12x2, can you tell us the name of the shop who originally wanted to replace the engine?

 

Autobahn in Fort Worth wanted to replace the engine.

European Autos (European Auto Care - Luxury Auto Repair) finally figured out what the issue was, but it's taken forever, as I'm FINALLY getting the car back today, hopefully.

They've been working with Jaguar and the part that finally solved the issue was replacing the sprockets (I'm told, and I'm assuming cam sprockets) but this was apparently the first time Jaguar has ever sold that part by itself in North America.

Between that and having to get everything approved through the extended warranty company, it's been a tremendous ordeal.

It also makes it very hard to get rid of the old Jaguar's stigma of being constantly in the shop. I wonder if it was always this way, where it's not that it's constantly breaking down, it only breaks once and then takes a third of a year to fix it!