That is true, it hasn't gotten any worst, same level & tone.

I'm on vacation next week, the XJR and I will have alot of time to spend with each.

Unless the wife get jealous, LOL!!

 

It goes away much later, between 2-3 min. (on idle warming) after cold start.
In "D" as the rpm's drops, it is louder.

 

Hello!
Another, XJR owner with an earlie -98 126k miles that has got the same noise, more tapping than knocking, but also with changed upper tensioners. Any news to the othervice beutifull super v8?
(seems as there are quite a few with same noise, are all sounding like this?)
/Per

 

Nothing changed.

 

Mine's done the same thing for the past 4 years-idles beautifully quietly when hot with just the normal 'rustle' from the valve train. Light tapping noise from a cold start until it warms up or the revs are raised.

Interestingly, the noise is louder in 'Neutral' or 'Park'. When any gear is selected the noise quietens down, so I'm thinking it must be load-related-maybe sloppy big-end clearances on a high mileage engine?

I would have thought that big-end problems would make the noise quieter on a cold engine with thick oil, whereas a hot engine with the oil thinned out & the idle oil pressure lower would have made the noise louder?

It does get a bit louder when the oil level drops-my oil level was between the low & high dipstick marks, so I topped the oil up to slightly above the high dipstick mark & the noise quietened down.

Maybe it's oil level related & a lower oil level gives a greater air space in the sump which amplifies internal engine noises?

The sump capacity was changed throughout the V8's life-cycle & there was a TSB to introduce a new dipstick with new markings for a different oil level on later models.

Either way, the car still drives exactly the same & there's no obvious faults anywhere-when warm the engine idles perfectly with just the 'rolling rustle' from the injectors & valve train.

 

We're fairly certain that it's the No. 1 big end. Next time we fiddle we'll note down the numbers on the side of the block and get the shells in, then perhaps one day we'll summon up the enthusiasm to swap it. (15 hours book time with subframe off/engine in situ; LPG conversion complicates this further though!)

No change in tone though, so not considered urgent yet.

 

You could try tho old shade tree knock search and disconnect each plug coil primary and listen foir the one that causes the most change in sound.

I have not looked at a Jag's knock sensor signal yet, but I wonder if you can see this knock on a scope. If so, you should be able to isolate it some that way.

 

Hello again!

Have checked some more, starting with sub zero degrees, cold engine.
Oil 5W40 fully synthetic OKQ8.
After the first 10-15 secounds higher idel, the enigne runs smooth with just injectors ticking and hizzz from chain/belts ex.
When fully warm, after approx. 20 min of slow town driving, the noise is there at ideal on park or neutral. As described, noise is not very hard but still following rpm clearly and is there up to 1500rpm, but i guess than everything else drowns it. I am going to try to disconnect the super charger to see if thats the source, and than maybe aux belt. Maybe it's always been there since I bought it, but how knows...
Noise is strongest at cylinder closest to airbox.
Could it be posible to reach big end of rod from underneath, by removing oilpan?
Had it open to change seal and have a look a couple of month back, and there where no parts from plastic or other. Secoundary tensioners are changed in 2011.
No oil consumption and feels strong.
Maybe I should just drive it as usual, if it brakes I will notice .....

Cheers!

 

It's not possible to access the big-ends from underneath by removing the sump pan. You've then got the 'structural sump' assembly with internal ribbing & then a windage tray under the crankshaft to block access to the big ends-engine out job, I'm afraid.

If the noise isn't too bad, then just leave it-I found that a thicker grade oil helped quieten the noise. You can justify using a thicker oil on an older engine where the mechanical clearances may have increased a bit.

You could try the 'motorsport/trackday' synthetics, such as Mobil 1 10W/60.

 

Structural sump can be removed with the engine in-situ. You need to drop the front subframe to remove the structural sump, but leaving the engine in situ avoids disturbing all the fuel/oil/cooling lines, electrical connections, or splitting it from the gearbox. (quicker)

 

Thanks to both of you for the very usefull info!
I actually did run it on bike oil 10w-50 OKQ8 Superbike fully synthetic during summer, but as temperature dropped below zero here in Sweden (Daily driver), I noticed that car was much heavier on starter, so I changed to the present 5W40 oil. As snows disapear at spring, maybe I should try to use the 10w-60.
I had that actually for an old Alfa GTV-6 -83 that I had during summer, both eaven in relativly high temperatures as 10 deg, the oil pressure was like 6,5bar at idel with cold engine. Soo, needed to have a 10-15 min warm up before I dered to drive it Didn't want to blow the sensitive gallery oil lines... So, not very practical.
Completly differnet question. How hard is it to check oil pressure or exchange oil pump? Is it the same, down with the structural sump...
A big thanks to all, for sharing your knowledge!!!
Happy Xmas...
/Per

 

Hey guys, even the thinnest weight oil (...0w-20, 0w-10) is way too thicker than a hot 10w-60, when the thicking noise is there. Then the engine is cold, so the oil temperature is very low. As we wrote, that sound is there only after cold startup. So I think, a thicker oil won't help, maybe worse.

You can measure easily the oil pressure. There is the oil pressure sensor at the oil filter. Replace it with a mechanical oil pres gauge while testing. The only problem that could be, to find a same threaded pres. gauge.

 

Very useful to know that-I once changed the big-end bearings on an old BMW by removing the sump pan together with the oil pump. There was enough clearance to slide the sump forward & down without removing or lowering anything else.

I guess with the Jag V8 it's a choice between a 'big job' of dropping the front subframe, or a 'very big job' of taking the complete engine out. I think on balance that I'd prefer your method of dropping the front subframe!

Alternatively, I guess the noise can be ignored if it's not too bad & the engine can be run on thicker grade oil. That'd be the cheapest option to start with

 

A Jag club friend has been talking to me about it for a long
time, and I finally decided to put some in my car, I have
molybdenum in this particular 8L of oil. I put a few grams of
raw element 42 in the oil.

I picked up 1mpg I'm fairly certain. I happen to know that
it binds with crankshafts. Why not put a few g/L in your
oil and run the Molybdenum in your car? Can't hurt. I think
that a permanent metal-metal contact preventor might
solve this problem.

I let the car sit for 4 days straight since arriving in FL, (wiped
out after a long drive from Tulsa) and upon the first startup
I got a puff of oil smoke which I have never seen on this
car. ( )

My car burned next to 0 oil in the period of 1650 miles on
Molybdenum, and on subsequent startup all is the same.
Perhaps it is just that the car has never sat still for so
long during my ownership! (I get stir-crazy if I don't
drive the car one day) (I am speculating that this metal
doesn't cause oil to start burning, my XJR has never
consumed oil, except .4L on an 8h track day)

Try adding this to the oil. I expect you will see improvement,
I just wanted a bit of extra MPG and I seem to be reaping
the benefits. I get over 20 on the highway almost always
now, and this car never did on longer trips before the stuff,
as far as I can remember. (I only made one interstate trip
without it, which was right after I bought the car. All subsequent
long trips were on roads with 65mph speed limits.)

The MPG benefits may be totally irrelevant sorry.. anyway try
adding the Molybdenum to the car, I have a feeling that a
few grams would go a long way in silencing this tapping sound.

TL;DR (for you guys who are short on time ) Add molybdenum
to your oil, I think it will stop the tapping sounds, if not give a
minor improvement)

 

It's a Super V8, so a SC motor.

The SC motor has one thing that the others do not. A thermostatic oil bypass. Perhaps in the cold position, the passage used is not adequate.

Is the oil pickup good and solid?

It's very interesting from the pictures that the low mark hole on the dipstick would seem to place the high mark almost at the bottom of the bedplate. Then, in the Silverstones, Jaguar specified an additional litre above that. That would mean the bottom sump would be full at all times.

BTW, is the pan removable without dropping/lifting something else?

 

plums:
There were at least two different dipstick lengths to accomodate different variants of the dipstick tube. I wonder if they also changed the dipstick length for the recommended additional quart of oil?

 

There was indeed a TSB to match the dipstick markings to the revised sump capacities for the 2 different types of dipsticks. The changeover happened around 2000/2001MY.

Looking at the handbooks for my own 2001MY car, the main handbook quotes the following oil capacities:

Engines without oil cooler: 6.5 litres
Engines with oil cooler: 7.5 litres

Interestingly, mine also came with the handbook supplement which quoted revised capacities for my 2001MY car:

Engines with or without oil cooler: 7 litres

So the oil capacity was effectively reduced for vehicles with an oil cooler & increased for vehicles without an oil cooler-I know not why

As for my own car, I was not convinced that reducing the oil capacity from 7.5 litres down to 7 litres was beneficial in any way-so I always run my sump level up to at least the MAX mark on the dipstick, which is the correct revised dipstick for the later oil capacities. I found that adding a bit more to take the level a bit over the MAX mark & back up to the original 7.5 litres capacity of the earlier models did make the tapping noises notably quieter.

 

There was one sump, two dipsticks and three specs.

The thread where Brutal and others discuss it in detail can probably be found by using "silverstone" and "dipstick".

I run at the highest level of the three specs.

 

I have new thoughts about the origin of our engine's knocking noise. I'm working in a Mazda service center, and one of those off car's type has the similar sound after cold start up. The off Factory gave us a service bulletin, that after cold start up, the speed of the flame (or burning) in the cylinders of these engine (Mazda3 1,4i) is too fast, because of the different intake air swirling under this condition, so the piston (pistons) tilts in the cylinder, and knocking on the cylinder wall.
They say this doesn't cause technical problem, but if the owner wants, we can change the pistons to modified ones.

Maybe if the cold temp. compression, or the injection is not so perfect in one or more of the V8 cylinders, we get the same sound. I don't know, it is just an idea.

 

I found, and attached the english speaking tech. info. Remember, it is about an off car, but as pistons are pistons, maybe....???