The crack on the tensioner body develops at the side which is not easy to see with the tensioner in place. This article has good info on tensioners Gen. 1, 2 and 3 - Jaguar XJ8 (X308) timing chain tensioner generation 1, 2 and 3 | jaguarbilder.se

 

You are right but the sound is located at LH. I doubt that RH tensioners are damaged and knocking is noticeable at LH side. I inspected source of knocking with stethoscope.

Dropping oil pan and inspecting pickup can be done later as I doubt this can influence knocking? Or do you see any influence there?

 

A2b is suggesting a look in the pan as a way to better assess what part remnants
you might find thus a better idea of where to look for the sound issue. It will also
give you a better mental picture of the overall status your engine.

 

Thanks for clarifying that Randy.

Z, since you don’t have any service history on this, it’s up to you to do detective work and dig a little deeper for this noise. However as we all know about these engines and some of the weak points within them, it’s always best to know by putting your eyes on said weak points. I have had these cars come in before and recently bought by the customer and I pull both valve covers to uncover that only one secondary timing chain tensioner was replaced while the original plastic was on the other side. If there was any red flags that looked like shoddy work was performed, I would have no problem draining the oil into a clean container to pour back in later. Then I would pull the oil pan and throughly inspect the oil pickup for any rtv, plastic guide bits and anything else that shouldn’t be in the way of oil flowing. I’ve also encountered oil filters that looked really old and the previous owner just added oil on a regular basis instead of fixing the real problem. Doing an actual oil change with a new filter that isn’t potentially packed full of debris is also another idea to increase pressure and volume.

With that said and you have the engine back to running condition, you could unplug each coil 1 at a time to see if the noise goes away or changes pitch for one particular hole. I would avoid having a coil unplugged for more than about 5 seconds due to unburnt fuel entering the catalytic converter can damage it.

A mechanical oil pressure gauge could also be of help with diagnosing but I know that can be time consuming and or a bit expensive with getting the correct fittings/adapters.

Does the pitch/volume of noise change at all when the engine gets up to full temperature?

 

Stojanovic, Randy, A2b - thank you for answers. Some comments:
- Jaguar was parked for a few years prior to my purchase
- I replaced all liquids including filters
- knocking is not always at the same level and sometimes almost dissappears when the engine is at operating temperature
- I am now testing it in the garage and not actualy driving it but after purchase I drove the car approx 1000km to bring it home
- knocking is clearly noticeable inside the cabin when driving
- mileage is approx 160000km (99k miles)

I will check the other tensioner, then what happens with coils unplugged and once I will have time I will remove oil pan and check what is inside.

 

Unplugging 1 coil at a time with it running will take the load off of that particular cylinder. What I mean by that is there’s no explosion inside the combustion chamber with it unplugged. You’ll still have compression in the cylinder but you’re technically deactivating it. If you have a wrist pin or rod bearing issue, the pitch and volume of noise should change substantially with it unplugged. This is a means of further diagnosing the engine for a noise.

 

I'd noticed some odd ticking/ knocking sounds that were inconsistent when my engine decided it was ready for a lot of new internals. If it's a ticking sounds that disappears at operating temperature, and obvious inside the cabin when driving, you might want to check the EGR tube from the exhaust manifold to the EGR valve. I'd had one XJR where the tube was disconnected at the valve (nuts backed off and lost gasket) that was a ticker, as well as a roughly 3/4" crack in the tube itself on another XJR that was a loud ticker. The cracked unit was noisy when cold, and the noise went away completely when at operating temperature.

The other is a worst-case scenario - pull the #1 coil and plug, rotate the crank to where #1 piston is at TDC and stick a dowel rod down until it makes contact with the piston. If you can push the piston down at all and you hear a click/ knock, it would be indicative of a bearing failure. If this happens, you're better off financially buying an engine to swap instead of rebuilding it. Rebuilds using genuine parts are far from cheap, and some parts literally are not available globally as new stock.

 

Today I tried to unplug coils but there wasn't any significant change related to knocking.

I also tried to move piston #1 and #2 at TDC and BTC to check if I can push it and hear "click" but either wasn't able to do it correctly or it is OK.

I also removed oil which was approx 40 km new and then removed oil pan and inspected deposited debris in oil pan and oil pump pickup. Oil looks clean but there are pieces of tensioner plastics and few aluminium splinters which look rather as leftovers from thread cutting and not classic wear splinters as they are really large. I will attach photos. Oil pan has entire bottom covered with 2mm thick layer of "greasy mud" which didn't mix with new oil. There is also most probably water in oil as I can see white streams and traces in deposited "grease". Any comments welcome.

In the end I noticed strange behavior when turning crankshaft - there is a play with noticeable "click" which you can hear and also physically feel at the ratchet everytime you change rotation orientation = most probably source of knocking while engine is running.

 

Hereby pictures

 

I did forget to mention, after bringing the #1 piston to TDC, on the downward stroke is where you want to test with the dowel rod. If no movement, #1 hasn't disintegrated the big end bearing, at least not to the point it's journal on crank. Sounds like this isn't the culprit.

Have you had any trans or rear main seal work done ever? Curious if the torque converter bolts are backing out if you're still hearing noise when turning by hand.

Oil pickup tube doesn't look blocked, but that is a lot of tensioner and guide material. Were the original primary guides and tensioners ever replaced? The big dark pieces look like they cracked off one of the primaries. My engine had less than 90k when it ate a bearing and the original primaries pretty much fell apart as I was taking them out.

 

The clicking you’re feeling is most likely a timing chain rubbing against the chain guide where the pieces have fallen off. Looks like a complete timing chain, guides and lower tensioners are in the near future if you want to resolve the noise.

I’m assuming you looked real close up inside the oil pickup screen also?

I’m not too concerned about the condensation inside the pan. Just clean the heck outta it is what I’d do.

 

I do not have any specific history records for this car. This is one of few I have and my first ever with such problem.

AFAIK these problems arise when the engine is running for some time with low oil level or with very old and degraded oil causing scratches at crankshaft and connecting rod bearings which is later on (dozens thousands of kilometers) progressing and delivering knocking. Most probably this engine. Connecting rod bearings are more sensitive and go first. Sometimes only one of them but others are also developing similar wear later on.

I am afraid I will have to remove the engine and refurbish it.

 

I am wishing it is related to timing gear fix only!
I removed oil pickup and washed it in cleaner. There is nothing left inside as far as my fingers can feel that

 

So what if you did the complete timing chains, upper/lower tensioners and guides replacement first then put it back together to reevaluate it? You did mention that unplugging the coils one at a time didn’t change the noise so I doubt it’s a rod or piston issue. With the amount of plastic in the pan, my opinion is that the clicking sound is still the chain on guide noise and that should be addressed first.

 

A2b I will discuss it tomorrow with local specialist but 99% I agree with you. Will get back to you tomorrow with details.

 

goes away above 1k rpm? lower tensioner seal is busted been there done that

 

Knocking is present also above 1k rpm and in fact in all rounds range.

 

Yes a full tensioner job is required. Don't do the zip tie short cut. Do secondary and primary and at this late date I would also replace the chains and sprockets.
Please don't let it go too long as the chains do move around and will start grinding on the heads and/or block.
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I would do the tensioners and guides, with new chains and see where
you are from there. You might be pleasantly surprised.

 

One remark. As I wrote I am hearing and feeling "click" when turning crankshaft with ratchet but only when changing rotation direction - one click. Suggestion is that click comes from missing plastic at tensioner and with contact between chain and metal tensioner bottom but it clicks only once. If this would be the case then you should hear and feel that click everytime a chain segment hits that metal part, don't you think?

I will again check pictons 1, 2, 7 and 8.