Hi all,

New owner to a 2000 XJR with 123K Miles and FSH.

The car developed quite a concerning knock/clunk/rattle in the engine on the way home the other day that caused me to park it up and not want to drive it until diagnosed. I am trying myself first before getting a specialist involved. Here is what I've found:

• The noise increases with engine speed, and was quieter on over run when driving. When in park, it gets really quite loud as I increase revs.
• At idle is seems to be happening around 4/5 times per second, fluctuates a little in volume and i can best describe it as a clunk. I've had several opinions who all say it doesn't sound like typical rod knock - which was my first concern.
• It is still present when both the aux and supercharger belts are removed.
• I have not dropped the oil yet, but there are no bits or metallic shininess obvious on the dip stick.
• I have tried the screwdriver stethoscope method on top of the engine. I can only hear it clearly knocking through the the two supercharger plenums on top of the heads, I can't pick it up while testing on the rocker covers, or front cover, or main supercharger body. This has confused me.
• The timing chain tensioners were done on record if i remember correctly around 10 years ago and 30-40k miles ago.

Any help or suggestions would be great, I will have a look at removing cam covers when I get the chance.

Thanks,

 

Welcome fdw, sorry your here under these circumstances....there is a known occasional wrist pin issue as well. Neither a rod bearing or wrist pin is what you want to deal with.
First suggestion for the site here, is it would be easier for us all if you'd put your Jag's MY and such in your signature. This way each time you post it's there and we know so we don't have to go back to your OP.

You'll want to download this, the X308 Workshop manual... https://www.dropbox.com/scl/fi/yet7a...u5biy&e=1&dl=0 ...you don't have to sign up, just prompt File top left and Download. It's too large to post here on site, thus the link.

I believe your best first move is to drop the oil pan. Be sure to drain the oil into a clean container to see if there are any sparkly glints of shavings and/or milky oil. When you drop the pan you'll have a good view of the rods, but make sure your oil pickup is clear first, it could be starving for oil if restricted and the reason for your noise. Run your finger around the inside of the lip as well. Do not be surprised if you find parts of your guides even though they were done 10 yrs ago.

Let the oil finish dripping (nothing like taking one in eye) then get a flashlight and look at the rod caps and see if you see any bright shininess like wear on the sides between them, then you may have identified the bad rod. You may be able to slightly move it barring wear.

Cam cover removal is pretty straight forward, you can follow the directions in the manual.

 

Can you upload a video of the noise, maybe directed around the engine top and bottom?
My concern is the 'belts off, noise still there' which rules out all the accessories unfortunately.

Super unlucky if it's spun a bearing. But, they can be bought.

 

Thanks both for you replies, I have attached a video here at idle hopefully you can view it.

I will also look at sorting the signature, i didn't end up seeing the new members section until after I posted my desperate plea.

I am also concerned the symptoms are leading to a bearing issue... Will update in due course.

 

Strange noise - it doesn't really sound like a bearing? More of a chuffing noise as if something is catching.
Either way you need to dive in...
cam covers are first thing to remove, then the timing cover and get a good look at the chains, guides and tensioners.
There could well be a guide adrift, or a collapsed tensioner both of which can give odd cyclical noises like this.
Yes, there is a crank damper pulley to remove and can be an issue with cheap puller kits - this is the one I recommend and gets the job done.
https://www.ebay.co.uk/itm/361750096...tion=view_item

A spun bearing knock is hard metallic and sharp, and travels - this doesn't seem to be - but could be video sound/movement.

 

Thanks, yes hard to diagnose will look where I can.

It does get violently loud when revs go up, and I did note the other day I could hear a light metallic squeaking in conjunction.

the engine seems to be running absolutely fine and smooth in terms of power when i was driving and no missing at idle.

 

That sounds like an exhaust manifold gasket leak...or thereabouts.

 

Isn't there a thing about exhaust manifolds cracking & giving a leak there?

I've been ignoring this information for a while as I suspect mine might be doing it slightly from the sound on cold starts.

 

Can't say for sure but I do agree that does NOT sound like a rod knock.
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Not rods, nor wrist pins, nor timing chain. Sounds more like belt touching something (fraying).

 

My car engine developed left manifold crack. Loud loud noise.

Video noise do not sound rod knock. Since it is coming without aux and sc belt. It is time to take cam covers off. And do not drive the car before fault is found and fixed.

 

possible loose sparkplug?

 

Sound like an exhaust leak, maybe a cracked manifold, or bad gasket.