Hi All,

Brand new to this forum--Wow! what a great resource!

I have a 2000 XJ8 with 64K mi. It just started knocking yesterday and has gotten a little louder. At first it was only under heavy load (hard acceleration). now it seems to be knocking all the time. less intense at idle and when coasting or steady speed and significantly pronounced knocking while under load.

I have had the vehicle since 27K mi. & I have had Zero engine work done to date. I am not getting any error codes (e.g. engine light) but I will be putting it on a OBD2 II scanner later today.

here is a video to help with what the knocking sounds like.

Any & all input would be most appreciated.

Thanks
RJH

 

here is a link to the video.

 

Do not run this engine any further, it sounds really bad. Do some reading on the tensioner issue.
It sounds to my untrained ear like it's ready to fail at any moment.

 

Thanks Rob. I agree it sounds horrible! Hoping someone with a well trained ear may be able to help narrow it down for me.

 

I'm gonna spitball this one and say rod bearing (s). I'll wait for the experts to chime in though.

 

If you have, indeed had the valve covers off, and the tensioners are fine,
it is possible that a lower tensioner has failed, and you are hearing the timing
chain slapping against its casing, or perhaps it has already jumped a tooth.

But the sound is more "clattery" than a ruinedconnecting rod bearing.

Allow me to direct you to a previous thread with a case of rod knock:

https://www.jaguarforums.com/forum/x...-needed-49916/

It is not an exceedingly common issue, but it has come from engines run/
cornered especially (taking turns, and starving the bottom end of precious
oil) with a low oil level. A half quart down wouldn't cause this problem,
but my guess is your car may have been run quite a long time at dangerously
low levels.

The video on Chinny4290's thread shows he has taken off the valve covers,
and found the tensioners to be in order, and the sound seems identical to
yours.

If it is, indeed, a rod knock, then the engine will need serious bottom
end work. Check the oil. You will likely find little shards of metal in there
if a rod bearing has started to splinter. If the level is low, this could also
be the smoking gun you are looking for.

Like the others said, do not run this engine again. And especially don't
give it any more than 3000 revs, even in an emergency situation.

If you find these symptoms to be in line with the aforementioned thread,
and you decide to replace the engine, then you can run it as long as you
like, who knows how long it will last before it loses the connecting rod.

In the case that it is a lower timing chain tensioner, then the same is true...
the timing is upset, and as the engine continues to run, the amount of
timing error increases. (i.e., jumping from tooth to tooth, possibly being off by
one or two) When you get the timing this far off, you have the serious risk
of bending a valve, which will render the car useless.

Granted, valvetrain work is cheaper than bottom-end work.

If you need a mechanic to take a look, tow the car.
(I would say you definitely should do this, don't take our
word for the diagnosis. I, for example, can only hear so much.)

Sorry you are having this issue.

Good luck,

Ian

 

This needs to get to the shop. It sounds like a rod knock to me but it is also possible that you have a failed secondary chain tensioner , which is a common and fatal failure. I would not run the engine again...get it towed.

 

I agree with Mots, don't start it again and get it towed if you can't take it apart yourself.

 

I'm afraid it sounds like a big end to me too.
Absolutely agree with the previous posts.

 

Not good.... +2 to the advice above - sounds like a rod knock to me.

 

Ian, Thanks for the reply and your input. It is So appreciated! & thank you for the link to Chinny's problem--I will read that thread in great detail-sota bummed that there was not a 100% verifiable conclusion to his issue (at least I didn't see one from my initial quick glance of the thread).

Couple of updates---


1. Checked oil level right after I heard the noise. Yes it was fairly low...car has had a recent history (last 3-6 months) of a very slight oil burning smell (when parked--but NO noticeable smell while driving) I attributed the smell to very small oil leak at the back of the valve cover gasket dripping onto manifold it would leave a dime size oil spot on garage floor from time to time. I had been pretty vigilant about checking & topping off oil, but, I may have contributed to this by not replacing the failed VC gasket right away.


2. I slowly hand cranked the engine to see if I could "feel" any noticeable friction points or resistance, but couldn't notice anything "suspicious"


3. I will drain the oil and inspect for any foreign particles.


4. I'll also repost with up close Pictures of the Tensioner- perhaps my eye is missing something.


Thanks again--This forum is like therapy.

 

Jagnicifant, I've merged your two threads into this one, it'll be easier for you to keep track. ;-)

 

Thanks Norri---I posted the 2nd time because initially I posted in the XJ 2003-2009 and thought I should really be in the XJ ( X350 & X358 ) XJ6 / XJ8 / XJR 2003 - 2009 forum.

Thanks.

RJH

 

OK snapped a shot of the tensioners No visible cracks or breaks take a loook-- Good? Bad?
What do you think?479789_193357354127660_1497220905_n.jpg

 

Can't say about the tensioners but the link is bad!

 

Hi Norri--Thanks for the heads up on the link.. (finally something that's easy to fix )

new link: Facebook

 

I listened again, I still think its a rod knock, but there is an outside chance that its a damaged tappet or cam lobe. Since the engine doesn't seem to be missing, its probably not a bent valve. Whatever it is, its mechanical and its in the rotating lubricated parts.

 

Hi All-Thanks for all the input so far!

I have had a few local mechanics listen to the noise (from the video -Not in person). General consensus is a rod knock. (side note: each of the mechanics I spoke with, said that they have Never seen a Rod go on one of these engines...esp at 64Kmi-hmmm?--any thoughts on that?)

So here's what I've got in terms of soft quotes (not knowing exactly what needs to be done)

If I am lucky it's just the bearing to the tune of ~$1500
If I need to put a Rebuilt engine in probably closer to $4-5K (all in)

Just for kicks I'll tell you what the dealer proposed---$8K factory rebuilt engine + $2K labor inc 1 yr warranty. nice!

Any thoughts on the above?

Such a shame cuz this is a beautiful car and rides like a dream.

More to follow.
RJH

 

If it is a big end (and I'd be prepared for a small bet on it) then it is loud enough to have damaged the crank.
Sorry to be a Jonah but I've run a few big ends in my time and never got away with it.
Rotten luck.
Re the choices - that's your call considering the market value of the car.
ANYWAY I'm pretty good at being wrong so, hopefully, it won't turn out that bad.
Keep us informed.

 

The normal 'killer' test is to drain the oil and look for white metal particles. A knocking bearing means the bearing metal has broken up and is passing into the oil in the sump. I had one like this on a Triumph motorcycle in about 1969. The particles are unmistakeable, being bright and shiny - a bit like gold panning, I would think.