2004 NBFL 1.8 Sport - Whining Noise from Left Rear

Hi folks,

First time posting, so I hope this in the correct section.

I have been gradually restoring my 2004 NBFL over the past couple of years, initially tackling rust issues and then moving on to the less critical items. A lot of the work has been done professionally, and the main jobs list completed to date is:

Repaired chassis rails;
Repaired rear sills and arches;
New (refurbished) wishbones/bushes all round;
New BC Racing BR coilovers (nightmare with ride height, but that’s another story);
Replacement Torsen (2003) differential. (Original Fuji (i think) had lumps of metal in the oil, and was making a strange noise, so was on its last legs);
Replacement rear wheel bearings;
New clutch,
New brake discs, callipers and pads all round;
New tyres (Avon ZV7).

As you can see there have been some big changes, but throughout all of this I have a persistent problem that I don’t seem to be able to solve. When driving with the hood up there is a constant whining noise from the left rear of the car which I cannot identify. I have read previous posts about similar issues, but I think I have already closed off most of the things suggested.

I’m definitely running out of ideas so if anyone has any suggestions to find a solution it would be greatly appreciated.

Thanks!

Steve 959, Might I assume that the whining is road speed dependant and that changing the wheel bearing(s) had no impact at all?

Regards,
tyton11

Hi tyton11,

Seems to kick in at above about 30mph I think, but once there I can’t say the volume changes much as speed increases. Just kind of a constant level.

Unfortunately the change of wheel bearings made no difference at all, and neither did the diff change. I just have added some sound proofing to the wheel arch and tunnel forward of the fuel pipe and over the diaphragm where the fuel pipe exits the boot the tank but that also made no difference.

Steve959,
Thanks for that; interestingly, I am suffering from similar and I have a NBFL Mk. 2.5 Sport. Like yourself, it doesn’t appear to be present with the hood down, or maybe it’s the wind and road ‘noise’ that masks the issue.
Are you able to jack up the rear wheels, so they are off the ground, then support with axle stands, in order to run the car, in gear, to see if the noise is still there, at an indicated 30mph?
Obviously chock the front wheels !
My car is currently at a bodyshop, but plan to do this check, when I get it ‘home’
tyton11

Tyton11,
Was starting to think I was imagining things, so interesting you have a similar issue with the same model. Yes, running on the stands could a good idea. Probably won’t have the opportunity to do so for a week or two due to work commitments, so if you have a go before me please update.
Have been very puzzled why it just seems to be on the left side, which is why I homed in on the fuel pipe diaphragm, because that is one of the clear differences between the left and right hand sides of the car that I could see.

Is this not the differential??
I seem to remember seeing somewhere that the differential had a certain amount of noise engineered in in order to give the car more of an authentic old school sports car feel.

I suspect it may be an illusion that the noise is coming from the left side of the car.
Your left ear is open to a direct line from any sound coming through between the seats.
Your right ear isn’t .
The road noise prevalent in the nc, due to the drains gives exactly this illusion.
The reason I know it’s an illusion in the nc is that I hear it as coming from the left but my passenger hears it as coming from the right

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Have you tried plugging the hood drains temporarily, could be just the road noise you hear from them. I guess they too have baffles like the NC drains, maybe dislodged or one missing?

Edit… sorry reply was meant for the OP of the thread.

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Hi 999to5 and MickAP,

Thanks for the suggestions. I’ll check things out and see how it goes.

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Just to add to the comments, I’ve just bought a Mk2 and it seems to have the same noise - somewhat similar to straight cut gears/a supercharger, but coming from the left rear. I’m going to get it jacked up next week to do general maintenance so will see if I can diagnose what’s going on!