Hey everybody,

I bought my ‘01 Jaguar XJR back in October with 107,000 miles on it and since I bought it I have had an (engine or supercharger) knock on cold starts.

When I bought the car I knew that if I wanted my bank account to exist in the future, i ought to do some research on the common problems and most importantly become active in the forums and when I did so I found out about the timing chain issues that my car can have. So after being paranoid for a day or two I went through the previous owner’s service records. I found records dating all the way back to before the car had 10,000 miles on it and I didn’t see t-chain tensioners listed (although I did find that the antenna had been replaced 6 times varying from $15.00-$137.00) so I figured the guy probably knew his car was literally a ticking time bomb and those tensioners were gonna go so I decide to replace the secondary tensioners

When I dug into that project I saw the the chain guides were badly cracked and I couldn’t just leave them so I ordered more parts and worked away until it was all done and I fired up the car and it still ticked, and I kinda panicked because I thought maybe my timing wasn’t set properly so I turned off the car and called a mechanic to come take a look and they said that I was too paranoid and that the timing was most likely set correctly. So I asked him what the knocking sound was and he wasn’t quite sure because he doesn’t work on Jags very often but we both were sure it had something to do with the supercharger.

So I kept driving the car and I posted on this forum about it and they said remove the supercharger belt and see if it knocks and it did so they said that my valves were most likely a little off but it would be fine to drive and it shouldn’t get any worse. Well I kinda think it’s getting worse and I was at another mechanic shop and I asked them what they thought it was and they said it’s probably the supercharger coupler, I also listened to the supercharger when it was at operating temperature a few days ago and when I’d rev the car it kinda sounded clanky. So now I’m not really sure what to do but I have 110,000 miles on it and I was thinking maybe a supercharger rebuild? What do you guys think the issue could be? Should I rebuild the supercharger anyways?

Thanks!

i can also post a video of the noise if you’d like

 

So, you did the tensioners....how did you lock the cams down? If they were locked down properly, you shouldn't have any valve issues.
I had a noise a few months after I did mine and found a missing tensioner neoprene cap. Replaced the tensioner, dug the cap out of the oil pan, and its been fine since. Not saying this is your issue, its what I found.

As for your SC, mine makes a cold start knock, and goes away in less than 15 seconds. I will be doing mine soon enough, probably shortly after the Rolex 24 next weekend. I recently received the new snout bearings (SKF) and fluid (Ebay)....I've had the coupler for awhile (Ebay). You want the OEM version, not the solid piece. This type with the spring... https://www.ebay.com/itm/New-OEM-Eat...72.m2749.l2649

 

I have driven it for a couple thousand miles but I haven’t done an oil change yet so I guess it’s a possibility that there’s something that came loose. I locked the cams and crank in place with the tool set from eBay.

And I wish my knock only lasted 15 seconds, my knock lasts for about 10minutes or so and it typically gets less noticeable as the time passes.

 

Did you remove the oil pan an clean out the oil pickup? The parts from the guides can collect up in it and restrict oil flow. You literally have to stick your finger up it and clean it.

 

I didn’t do that when I replaced the timing parts, I didn’t know I was supposed to.

would I be able to connect a scan tool and read oil pressure to see if it was at the right pressure? That would tell me whether it was restricted or not

 

I wouldn't trust it, its not hard to do. Yeah its a pain to drain the oil, but dropping the pan is easy and clean out is quick.

Because if you trust the reading and keep going to other things, you'll kick yourself later for not doing this simple process if it doesn't work.

 

What kind of knocking do you have, how loud? Is it actually more like "ticking" that seems to be coming from the supercharger or from under the supercharger, or from one or the other cam cover? During the 10 min. arm-up, does the ticking disappear when you slightly rev the engine, to about 1200-1300 rpm?

If there is no ticking immediately after cold engine start while the idle rpm is higher, comes in when the idle rpm drops as the engine starts warming-up, disappears when revving to 1200-1300 and almost completely disappears when the engine has fully warmed up (~10 min.) then it is the same ticking that I have on my SC engine (Daimler Super V8). A number of other members have reported same, I think mostly on SC engines.

This tick is a bit of a mystery and, even though I have recently replaced the heads with very low mileage ones, installed new cam followers and carefully set valve clearances. The ticking does not seem to get any worse - always same and it completely disappears when my engine reaches 88C (I have an additional digital temp gauge). So, I am not bothered with it as the engine runs nice and smooth when warmed-up and it is not present when I restart a still warm engine after sitting for an hour or so. It only goes through the ticking "sequence" when started from completely cold. I will, at some point, try with checking and re-setting of all valve clearances but I am not in a hurry.

 

How about removing the supercharger drive belt prior to a cold engine startup? If the noise goes away on first startup, you know it’s diagnosed as a charger issue such as a coupler or a bearing. If the noise still exists with the belt off, then likely an engine problem or maybe a pulley noise??

 

As the first thing, I check without the supercharger belt (and so has Kroeger, see 1st post) but no change. I also checked whether the ticking changes with engine load (to see whether it is related to the crankshaft big end bearings) by listening with and without AC compressor engaged, at neutral and with "Drive" engaged, but there was no effect - the ticking is just rpm related.

I also listened to all injectors with a stethoscope and found some ticking louder than the others but it was difficult to put the blame on them as, if it was injectors, the ticking would be quieter but who knows. The Jag injectors seem to be somewhat louder than injectors on other cars. I could not try with unplugging them one by one as it is impossible on an SC engine.

 

If you didn't change the primary chains probably you have stretched chains that's what make noise you hear

 

As I understand it, there are rubber seals between the supercharger and heads. These can harden and shrink with age, causing the sound you are hearing. Might be time to change them.

 

As part of my work on replacing the heads etc., I have also replaced all chains and tensioners/guides with genuine Jaguar ones. Also replaced the rubber seals supercharger to intake and even installed the sound deadening pad under the supercharger.

 

Sorry guys I tried to take a good video but it’s pretty much limited to four seconds of video before the attachment is too large

The first video is me shifting from park to drive.

As you can hear the car is embarrassingly noisey, between the knock and the belt squeal, it makes me feel a little better that my windows are tinted😔.

Anyways back to trying to solve the issue. The knock can go away at the right rpm. I also noticed that it smokes quite a bit on startup, it’s white smoke but I don’t believe that it’s a head gasket but I’m not entirely sure and I think head gaskets usually smoke a lot more than my jag did. Also the smoke is unrecognizable. It smells bad and I cannot describe it besides chemically smelling. It almost smells like when you replace gaskets on a car and start it up for the first time, I’m not sure if that is a smell lol.

 

I also bought a mechanics stethoscope to help me narrow down where the noise is coming from and it seems that when I place the stethoscope right on the plastic valve covers I hear a lot of ticking but not like the deep knock I’m concerned about.

When I put the stethoscope on the supercharger center piece I don’t hear much knocking or ticking.

but when I put the stethoscope on the two metal parts of the supercharger that have “supercharged” written on them it seems to be where the loud knock is coming from.

I also heard a pretty deep tick coming from the injector too.

It could be what m. Stojanovic has as well but I’d kinda like to make sure I’m not messing up my motor or supercharger. And everytime I drive it, it makes me nervous that maybe I misdiagnosed it to you guys and I’m just ruining something. So I just wanted to double check.

Thanks for all the help, hope this information can get help get the answer.

 

If it is a "deep knock", it could be one of the rod bearings having some play. The smoke from the exhaust could be engine oil burning suggesting an overall somewhat worn engine. A knock from a worn rod bearing, if not too much worn, can almost disappear when the engine warms-up.

You can do the following tests:

1. Remove the spark plugs (cold engine) and see whether they are oily or sooty.

2. While the engine is knocking, at idle, engage a gear and see if there is any significant change of the knocking intensity. You can add load to the engine by also switching the AC and the high headlights on (for additional load from the compressor and the alternator). If the knocking gets significantly quieter or disappears, then a rod bearing would be a suspect.

 

I had the same knocking problem from the supercharger on cold starts. I changed out the supercharger oil and it went away. The oil I used was for the supercharger, AC Delco brand I got from the Chevrolet dealership, 2 small bottles for about $25, but you can get it on Amazon in the link below. There is a small drain/fill plug at the base of the snout, driver's side. Use an allen wrench to remove the plug. Draining was done by sucking old oil with a syringe with an 18" tubing attached, then fill with fresh oil to plug hole level. The oil smells horrible, like vomit. After that, the knock went away.

Supercharger oil can be found here on the Amazon link:

 

M. Stojanovic - The knocking get significantly worse under load so according to you that would lead me to believe that it’s not rod bearings. also the smoke doesn’t smell like it’s burning oil.

I am going to have a non-jag but highly experienced mechanic look the car over and while he’s at it he is gonna see if he can figure out why it’s knocking

and maybe I will just swap the supercharger oil as it doesn’t sound expensive or difficult. Maybe it’ll help or fix the issue.

 

take the belt off and upload

that sounds kinda like my car with a worn out coupler

 

Well I took the supercharger belt off again just to be sure and it still makes the knocking sound, It didn’t make the knock on startup but as soon as I put it in gear it knocked pretty loudly.

So that means that there is no way it is my supercharger causing the knock right?

 

Have you done a compression test?