Yes, it's another one of those "my engine is making a ticking noise help!" threads. But I'm really at a loss with what to do to diagnose this one.

The only things I've done to the XJR recently (driveline related) are oil and replacing the starter, and repairing a vacuum line going to the purge solenoid. I don't remember hearing this noise after doing my transmission job, and I haven't driven the car a ton since then. A little after doing the starter job, I took the car for a somewhat spirited drive with a friend, did a couple hard pulls etc. We stop at one point and he gets out and notices the engine sounds kinda off and rattly when idling. Seems to be driving OK except some power loss at higher RPM. We get back home and I see the broken vac line, explains the power loss. Repairing the line hasn't done anything to solve the noise.

I've done a bunch of things to try and diagnose it so far. It seems the noise only happens at idle, and only once the car is well and thoroughly warmed up (temp gauge at middle, and driven a few minutes at least after that). Removing SC belt didn't solve it. Stethoscope didn't help pin down a location by much, except that it might possibly be more noticeable in the right bank. They didn't pick up the ticking from the starter or any accessories. Seems like it's more than just the ticking injectors, the noise is much deeper sounding than them. I put some fuel system cleaner in the tank, but of course I haven't been able to drive much to let that run its course, with worries about the noise. I pulled the RH valve cover to see if there was anything obvious, failed tensioner etc (I did all tensioners and chains when I first got the car). LTFT's are okay-ish when this is happening (+7.5 bank 1, +4.5 bank 2). MAF cleaned, PLB cleaned, all the usual maintenance stuff. Hooked up a vacuum gauge to the port between the V8-plate and fuel pressure regulator, that seemed OK vacuum levels, and steady. Pulled spark plugs on RH bank and stuck a borescope in to look around, nothing exciting there

I'm pretty lost on what to check next. I might try and reinstall the old starter for testing, just to see if that's what's causing it. It wouldn't really make sense though. The only other guesses I have so far are failing oil pump, or a leak on the exhaust somewhere before it reaches the cat. Wouldn't be the first time exhaust issues caused really weird noises. Maybe the oil pressure is just getting a bit too low when fully warmed up? I don't even know if these are on the right track though, the only thing I could think of to diagnose it as exhaust would be to get a small rubber hose, stick one end in my ear, and the other around the exhaust header while the noise is happening, being very careful not to burn myself anywhere...

Also obligatory videos:
https://drive.google.com/drive/folde...wd?usp=sharing

 

Maybe oil pressure on the low side causing lifters to make noise and chain tensioners not to be just tight enough. Or just noisy injectors.

 

no lifters but it has buckets that could possibly cause noise.

 

Do a compression test after the engine is warmed up. A loose valve seat can sound like that.
When I purchased my first Jag, 2000 XJR, it had a ticking sound similar to that. My not knowing much about the Jaguar engine at the time I thought it needed a valve adjustment. It turned out that the engine was overheated and that caused a couple of the valve seats to come loose.
I'm sure you didn't overheated your engine but one of the valve seats might of come loose with your " spirited driving" with the engine at temp. I not saying that that is definitely what it is but is one thing to check out while trying to diagnose.

 

Bought a cheap compression tester and raced the coming rain to get that done. Managed to do the whole right bank (the suspect, maybe noisier one) and here are the results. Using the "old v8" numbering used in DTC's, where right front cyl is #1, next cylinder in that bank is #2, etc. Numbers are results on first pump, and after 10th pump. Engine warmed up thoroughly to where it was making noise, and tested as soon as possible afterwards to prevent much cooldown from affecting results.

#1: 30, 110
#2: 30, 105
#3: 30, 110
#4: 30, 110

Seems OK, though maybe a bit low?
May try the starter swap if weather permits tonight, just because it's the only thing that I know has changed since before the noise started. Maybe it's something simple and bizarre like the starter rubbing the drive plate.

 

Before you go changing out your starter, just double check your work on it. I would get the engine up to temp and check the compression on the other side as well just to compare. As long as it’s within 15-20% of each other.

 

Reinstalled the old starter and it didn't fix the noise, unsurprisingly. No witness marks on the new starter, bolts were right, so it's probably not that. Much quicker of a job the second time around.

I'll try to get the other bank compression some time this week, then I guess I'll get an oil pressure gauge and make a mess testing that when I have more time.

 

Attempted to test oil pressure today, was feeling pretty good getting out of work on time and thought I'd give it a shot... only thing I managed to do was spill a bunch of oil past my drain pan onto the parking lot.

The oil pressure sender / switch fitting is M10x1.25, not M10x1 like every kit has. Can't have it easy. Guess I'll have to spring $20 for an adapter I will only use once, since it seems like such an uncommon need there's virtually no adapters available quickly. Gonna search a bit more and probably order that part, hopefully have it in for the weekend. I saw there was another disconnected sensor tucked away behind the oil sender (I'm assuming it's an oil temp sensor) but the threads on that were much larger than anything in the kit.

 

Okay we've got more numbers. At cold start, oil pressure gauge shows 70psi. Slowly decreases as engine warms and idle lowers. At fully warmed idle, when the engine is making noise, the pressure decreases to about 20psi. Gauge seems to show steady, no vibration in the needle, but it's a very long hose that's probably mostly full of air, so that may be creating a lot of damping.

What's next?? Try a cheap 0w-40 or 5w-40 oil and see if it deadens the noise, or raises oil pressure? I'd hate to just waste oil on diagnostics, but it'd need to be changed anyway if I do the oil pump I guess.

FWIW, the adapter needed for anyone who wants to do this test, is AdaptAll 9235-10X1.25-02

 

That's not bad pressure at warm idle, same as my 97.

 

it’s fine

 

Cool. I'll hold off on messing with the oil then. Definitely also don't want to do an oil pump job unless absolutely necessary.

So what's next to diagnose?

EDIT: I poked around with a stethoscope for a lot longer and it really seems like the rattling is coming from the RH bank... I can hear it through the scope somewhat when touching the RH exhaust manifold bolts, and when touching the RH valve cover bolts. Touching the LH equivalents is relatively quiet. Maybe it is one of those valve seats just starting to come loose a bit? Or I need to check valves for clearance?

 

Well... RH bank valve clearances checked. Seems fine I guess? The FSM calls for 0.20mm for intake, and 0.25-0.30mm for exhaust.

 

What do your tensioners look like? My '03 XJR was making a little noise, pulled the cam covers to find that the bottom slipper had degraded enough to crack away and the chain was eating the metal casting. Replaced primaries, secondaries and guides and it was as happy as could be.

Also had another noise issue with my '07 XJ8L. Thought it was tensioners, ended up replacing primaries and secondaries and the noise was still there. Read about some VVT actuator failures (wouldn't happen on your XJR as it doesn't have VVT actuators) and ended up swapping intake cams from a known good engine, reset the timing, noise was still there. Finally found a video on YT about a bearing failure on the con-rod, brought #1 to TDC and was able to push it down with a .25" dowel rod. Point being, before spending time and money on parts for something that's hard to trace, you might check that also just to make sure you didn't smoke the bottom end. IT shocked me, the engine was quiet as could be when headed out to lunch, then when I was on my way back home it sounded like there were rocks inside the crankcase.

 

I will try the dowel trick, I guess I didn't really think about it being a bottom end issue since the noise seems to disappear above 800ish rpm. Guess it's a simple enough test to do though, and just one more bit of peace of mind.

My tensioners were replaced about 45k mi ago. BUT...
I went ahead and replaced the oil with 0w-40 out of frustration, and just to eliminate another possible cause. No luck there, of course. Though things might have seemed slightly quieter after my short drive, the rattling was still there so I called it a night at that point, again frustration and exceeding time planned for this task.
While I had the oil drained, I pulled the pan to inspect for broken bits. Found a couple of very small slivers of plastic that looked like parts of primary guide. It's possible that they might have remained stuck somewhere in the sump tray from when I got the car (and it had broken primaries), and only now worked their way into the pan. Or I've got a bum primary guide that failed early. Suppose I can try and stick a borescope down there again, look closer at the primaries if possible. Don't think it's possible to loosen the primary chain enough to expose the guides, without pulling the timing cover, but maybe I can see something without doing so now that I have something specific to look at. Seems like a weird cause for the noise, but at this point weird causes are all that's left. It'd also explain why the noise isn't very localized, and seems all over the place on the engine, sort of in the front, sort of in the RH bank, etc.
Also, I found that my oil level was way overfilled. Think I underestimated the effect of the sloped lot I have now, on the oil reading. Really hope that it's not some stupid mistake like that, that ended up damaging my bottom end after all. And just after having done a transmission replace.

 

Hi nilanium,

The noise in the videos does sound more top-end related, but it could very well be piston slap, so it would definitely be worth doing the dowel test on all 8 cylinders as 03_jagXJR suggested. Our '04 XJR spun a rod bearing while my wife was driving it, and it was easily detected by bringing the cylinder to TDC and pressing down on the dowel.

The windage tray between the lower block/bedplate and the upper oil sump should theoretically reduce the chances of the oil pump inhaling frothed oil, but I don't think you can rule out damage due to oil starvation because of the overfilled oil.

Your compression measurements seem low. Have you measured the other bank? Did you try adding a little oil to each cylinder to see if the readings increased significantly? If they increase, suspect the rings are worn. If they don't increase, suspect a valve/timing problem.

Following your thread with great interest!

Cheers,

Don

 

Well, I did the dowel test. Tried to get the engine as thoroughly warm as possible with it idling in the driveway before doing each bank, seemed to cool off fairly quickly though with the bay open and a cooler day today. Anyway, all 8 cylinders felt perfectly tight, no play felt by hand, also tried cycling each cylinder to ~90deg past TDC, and hitting the (aluminum) dowel with a rubber mallet to see if I could hear a clack. All silent. Seems like good news.

I had a bit of a scare yesterday when I went to warm it up for the dowel test and it began to stumble like crazy at idle after starting. Thought I had jumped timing, so I shut it off and started to go through things. Noticed my fuel filler was full of water after a serious rain storm the night before, combined with a totally clogged drain... so I've got a bunch of water in the tank now. Going through various things to try and drain it, still over half a tank's worth of gas so it's a bit much to just drain off and refill. I used the fuel pump + jumper on the relay pins to push out about a gallon of whatever mix of water/gas. Put a bottle of HEET in there, let it sit for a couple hours. Still stumbling like crazy afterwards, and seems better once full warmed up, but LTFT's are still pegged at +15 at warm idle, with STFT's at the same +15-+20. I guess due to the remaining water? I'll try to drain it into a couple large buckets, let it sit for the water to separate out, use a transfer pump to suck out the bottom of the separated mix (hopefully most of the water), and pour the contents back into the gas tank. Maybe another bottle of HEET after that process just to be safe.

Also double checked timing on both banks just to be absolutely sure. Both were good, no skipped teeth. But now, my LH cover is leaking oil (probably a bunched up gasket, they're a pain to line up right), and my RH bank has a cam cover bolt snapped off inside the head. Fun times. Maybe I'll go stainless on the replacement bolt, cause why not (actually after looking at Mcmaster, this specific bolt is 10x more expensive in SS vs grade 8.8... maybe not). Borescope didn't show any issues that I could see, though I will review the recorded video on a bigger screen than my phone, see if there's anything I missed.

I'm tempted to just drive it on some mellow roads for an extended period to see if the noise works itself out, with the new oil. Every test seems to come back OK. It does seem to be somewhat quieter. Of course, I can't really test easily now due to the other problems mentioned above.

 

Oh my god this was over a year and a half ago. In any case, returning with the solution to finally close this thread, after driving with this embarassing idle rattle for so long.

The problem was... drumroll... RH bank secondary timing tensioner!
I replaced the tensioners when I got the car (about 50k miles ago) but I guess something happened to that one in particular. Its actuated guide looked fairly worn when I pulled it, but the thing that got me thinking about it was the nature of the noise (dependent on oil pressure, the rate of the noise related to the engine speed, and sort of irregular thru the engine rotation, as if multiple valves were making noise... or the cams were creating backlash from poor tensioning) and how the tensioner felt very "loose" when I did valve cover gaskets recently.


I took it apart and didn't see much, some wear on the piston surfaces but not sure if it's enough to create a huge loss in pressure. There's also a handful of check valves in there, so maybe one of those stopped working properly resulting in poor tensioning. Who knows.

Anyway, one fresh secondary tensioner in, and now it's nice and quiet at idle again. It feels so good to be rid of that embarassing noise, now I can finally again enjoy that smooth almost subbass exhaust idle from outside the car once it's warmed up. The idle feels much smoother too when in the car.