Mine has started making a howling noise at tickover which eventually stops when I get higher up the revs. I think it's just moaning I've not spent enough money on it this year, 2 weeks before MOT time.



Anyhow back on topic; could there be anything air intake related? Would a damaged hose that only 'failed' under increased demand have anything to do with it? Have you Tried the SC belt off yet? I guess if it's only happening under mid acceleration, short of hiring some kind of stunt man the stethoscope/screwdriver to listen to various parts is not going to be much use. :-\

EDIT: the belt/idler pulley idea is also intriguing. Is it worth tightening/loosening the idlers for a short test drive? Wondering if the belt has stretched so that when it's under load it slips. When you've had a run, are there any smells under the bonnet? Formerly happymadison1978

Dan, have you checked for air leaks? Smoke tested it? Easy DIY job with a disco smoke machine!

We see a LOT of diff related whines from your era SC’s as they get older! Have you checked fluid’s & levels?

Thanks for your replies guys!

Not sure if it could be the belt as it's a very low pitched noise, but potentially could be an idler, although surprised it can be so loud in the cabin - I have a squeal on wet/cold start-up so maybe it is related. Not taken the belt off yet because it's a pig of a job to do - getting there though!


@Craig - I wonder, if it was Diffs it would be road speed dependant rather than RPM? The smoke test intrigues me, how do you stop the engine fan blowing it all away? I'm going to look into this asap as I can do it myself on the drive, plus I need a smoke machine for the next LAN Party at work.

Further info:

I don't believe the noise is audible outside, I've opened the windows and can't hear it at all as the sound of the engine outside at 2000RPM drowns it out, yet in the cabin the noise is louder than the engine.

Today for the first time I heard the noise while under engine braking at the same RPM - does this rule out intake? I assume there is no/little air going through the engine when the throttle is closed? 

Dan, my advice would be to remove the pollen air filter assembly and take the car for a drive as this will give you a clearer indication of the noise - I drove mine with that removed and what a difference in noise from the Supercharger !! You will need to remove the engine cover to take the pollen filter assembly out (quite easy)

There is also a by-pass valve in the system (wastegate in turbo terms) that may be the cause of your noise as at periods where the engine doesn't need full boost this valve will be operating.

Description: The by-pass valve attaches to an opening in the induction elbow and controls a by-pass flow from the intercoolers back to the inlet side of the supercharger. At closed or partially open throttle settings the by-pass valve is fully open. As the throttle opens, the by-pass valve progressively closes to reduce the bypass flow and increase the pressure of air supplied to the engine.

Worth a try.....as it sounds to me like this might be the source of your issue..... Stolen / Gone: 2006MY Supercharged LPG Autobiography - Zambezi Silver with Sand/Jet/Jet Oxford Leather.....

Hi Dan, I believe I have a similar noise as you. I had read somewhere that there are numerous LR tech bulletins with various noises. Have you had a look through any of those?

I recently fixed the windscreen (warped wiper cowl) noise on mine and this drone is almost unbearable now. I should note, it does not bother my wife.

I have not noticed the RPM, speed or load differences. If I had to guess, I'd say mine is speed dependent (but that could also be load).

The only thing I do know about it is that when I leave off the throttle it's gone instantly. When I get back on the throttle, the slightest amount (3-5%) it comes back, more throttle equals louder noise. Sometimes I can get it to be quieter if I play with the throttle on/off/on/off (very lightly, so that you couldn't notice it as a passenger).

It could sound like power interference with the radio/speakers - but I am almost certain that i've turned the radio off while hunting for the noise.

Hi Kyle,

Glad I'm not the only one struggling with this. Does your noise go away if you increase the throttle?

I'm so frustrated, having wasted hundreds if not thousands now on "experts" not to mention the ballache of being without my car for days/weeks.

The next step is to pull the SC belt off and see if that does anything, or even if it changes the pitch of the noise etc.

Dan 

When driving today the noise was really noticeable, frustratingly you cant hear it at all on the dashcam:

https://drive.google.com/file/d/0BwVnQ7k3Z-jYamxlcTJ2MVY1aXM/view

https://drive.google.com/file/d/0BwVnQ7k3Z-jYZE5Cc2o2NURERlE/view 

just a thought Dan, why not spray wd40/water/something on each of the pulleys and see if the noise goes away when you rev. ... - .- -.




Y. O. L. O.
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dhallworth wrote:

Next time it's making the noise, try turning the air con off, my SC made a noise on partial throttle and when switching the air con off it stopped. I've got a new compressor here I just haven't got around to fitting it yet.

David.

Sorry should have updated, all new belts, pulleys and idlers a couple of weeks ago. 

Did that fix it?

I noticed mine will go away if i hold 70-75mph for a while. comes back at 80mph. Been messing with ride hieght after getting the IIDtool lately and think it may have changed a bit, Im starting to think struts in my situation.

Hi Dan,

Apologies resurrecting an old post. Did you get to the bottom of this in the end?

I've got the same howl in mine too. 07 MY.

Ta,
Sam

Sam,

Still no further forward - somehow I seem to have two threads running for this. My latest was to buy a set of "Chassis Ears" basical remote microphones one clips all over the car to try and trace the noise. Not played with them yet.

D