X350 XJR Strange engine bay rattle (with sound clip)

[andrewrob]

My father in law has noticed a strange rattle in the engine bay of his XJR.
The rattle is constant at idle and if the throttle is blipped I can only liken the noise to a marble dropping onto a table and bouncing a couple of times until it rests.
I've recorded a sound clip (don't know why I didn't do a video) but the quality isnt great. I can get a video clip tonight if that would be any help.

It sounds like something flapping almost, like a throttle butterfly but I'm not sure.

Any help would be much appreciated!
http://www.youtube.com/watch?v=HMrx-L8kjK4

[bob1179]

I couldn't make it out too well on my laptop computer.

Have you looked under the bonnet to make sure nothing has come loose? Especially around any of the drive belts? Or alternatively, something loose around the inlet?

I'm afraid I'm not particularly au fait with this motor, is it still under warranty? You could always pop it into your local dealer and get them to take a look.

Edited by bob1179 on Wednesday 29th September 10:28

[andrewrob]

To be honest the sound quality isn't great anyway. That was recorded from under the bonnet.

I've checked for anything loose and couldn't find anything. It sounds like its coming from the engine but low down. I'm going to do a better video tonight.

[drummerboyXJR]

If i were you i would avoid revving that, it doesnt sound too well!

[andrewrob]

drummerboyXJR said:

If i were you i would avoid revving that, it doesnt sound too well!

The crappy sound quality makes it sound worse than it.is. The engine note is smooth its just the knocking sound thats odd. Is there a double butterfly arrangement on these? Like a normal butterfly up at the throttle body and a second one.further back in the intake pipe?

[drummerboyXJR]

Just the one, as far as i know.

[andrewrob]

What about the supercharger does that have a separate intake and or butterfly?

[drummerboyXJR]

Its got several components in there which could give you a noise, but they are spinning real fast, yours sounds fairly infrequent?

[andrewrob]

Yes doesn't seem to change with engine speed, more with the throttle bring opened and closed and a slow noise.

[andrewrob]

Ok, had a closer look tonight. If I use a screwdriver to listen to the sound it seems to be coming from just above the pulley shown in the picture below. Would this be caused by a water pump on it's way out?
I've also recorded a better video too and you can hear the sound very clearly, especially when the engine is turned off at the end.

http://www.youtube.com/watch?v=BDwZ2igqeMY

[drummerboyXJR]

Sounds like top end, which is good news. End float on the supercharger bearing, maybe?
RRW, help me out here??

[drummerboyXJR]

OOPs, RW774, i meant

[andrewrob]

drummerboyXJR said:

Sounds like top end, which is good news. End float on the supercharger bearing, maybe?
RRW, help me out here??

Sounds expensive, any ideas on cost?

[avos]

I would guess the supercharger coupler, that can rattle pretty loud as the noise is amplified thru the supercharger. Relatively easy to check/change.

[andrewrob]

That would make sense. Have spoken to a chap at Jaguar but they don't sell any parts for the supercharger, just a complete unit. Would you be able to recommend a supplier?
Also is it something that can be checked and fitted at home or is it a garage only job? I've read a bit about the previous XJ 4 litre not being too bad but nothing about the 4.2.

[corradokid]

id remove belt first to have a listen, will be ok for a short time.

[NormanD]

avos said:

I would guess the supercharger coupler, that can rattle pretty loud as the noise is amplified thru the supercharger. Relatively easy to check/change.

That was my thought

Andrew, where are you in the UK

[andrewrob]

NormanD said:

avos said:

I would guess the supercharger coupler, that can rattle pretty loud as the noise is amplified thru the supercharger. Relatively easy to check/change.

That was my thought

Andrew, where are you in the UK

Derbyshire. I've emailed a chap in Aberdeen that I've seen recommended on here and the Jaguar forum to see if he stocks the coupler. Have you ever swapped one on yours? I'm not sure how complicated it would be.
Thanks

[NormanD]

andrewrob said:

NormanD said:

avos said:

I would guess the supercharger coupler, that can rattle pretty loud as the noise is amplified thru the supercharger. Relatively easy to check/change.

That was my thought

Andrew, where are you in the UK

Derbyshire. I've emailed a chap in Aberdeen that I've seen recommended on here and the Jaguar forum to see if he stocks the coupler. Have you ever swapped one on yours? I'm not sure how complicated it would be.
Thanks

Changing the bit isn't complicated, just time consuming as it would be best to take the charger off before opening it up

As you are in Darbyshire try EAPJ Ltd in Darby 01332-265826 Dan knows his stuff on these cars

I think the person you are talking about in Aberdeen has gone out of business or at least I've been told to say well clear

[andrewrob]

Thanks for the heads up on that one. I'll steer clear and give this place in Derby a call in the morning. Thanks for your help, will let you know how it all goes.