Hi there. I’ve had this issue with my R53 for months now that I can’t seem to get around. Ever since I did a SC service the car has made a high pitched whistle noise from the pulley side of the car. This noise is audible at idle and raises in volume with engine revs. The noise is not present with the belt on the car so I know for sure it’s coming from anything that’s driven by the belt. A month after doing the SC service I installed a 17% SC pulley and the noise got noticeably louder and still persists. I seriously doubt I have SC damage as the SC works perfectly fine producing plenty of boost and producing its whine under the other whistle. The SC worked brilliantly before the service and works exactly the same after. I know for a fact I did the SC right. I put the right amounts of oil (and right specification) into each chamber and changed all the gaskets. I’ve even pulled the SC back out again to check the gaskets are sat properly and it seems as though they are. The noise however still persists. I’ve thrown 2 new belt tensioners at it, a new water pump and a new idler pulley yet nothing has fixed it. And I doubt it’d be the belt because the issue has pertained on two different belt sizes. I’m thinking the issue may have something to do with perhaps the AC or alternator pulley. I’ve run a stethoscope around the area but the noise seems to be originating around the SC pulley and obviously resonates through the metal of the tensioner arm and makes it hard to deduce where exactly it’s coming from. I’ve rotated the SC pulley by hand and there’s nothing out of the ordinary. The pulley still rotates smoothly but you can still feel the SC screws rotating (a bit of resistance/roughness in the pulley but nothing bad). Other issues it might be include a vacuum leak but all the vacuum lines to me look okay, on top of that the intercooler boots are also okay and I’ve swapped them for silicone ones. I’m probably going to end up biting the bullet and end up going to the mechanic but I know they’re just going to say the SC is buggered when I seriously doubt that because the sound is no where near the same as other people’s SC problems and my SC is perfectly healthy. It’s only a high pitched whistle that doesn’t affect anything only my pride. Lastly I’m thinking it could be an air leak from where the supercharger connects to the cold side intercooler horn. Let me know what you guys may think it could be, is there anything else I should look at? Cheers

 

To what extent did you disassemble the SC when servicing it? Did you remove/install the pulley to replace the seal on the main shaft? It's very easy to brinell a bearing if it's not supported correctly when doing press fits.

 

If you have a automotive stethoscope, try listening to the alternator & a/c compressor …

 

Had the entire supercharger out to service it. Fitted an entire supercharger service kit (includes all gaskets, o-rings, oil, etc) replaced water pump at same time. Only a month or two after that I did the reduced pulley with the supercharger still in the car. All I did for that was pull the old one off with a proper puller and slid the new Alta one on just like you’re supposed to as it’s not a press fit. Unless I did anything wrong I can’t see how that’s caused bearing failure.

 

Bearing failure wouldn't produce a "kettle" sound. It's more likely associated with an air leak. Take some soapy water and apply to the likely areas where air might leak and you should be able to ID it.

 

How is everything going now?

 

I only just gotten the car into the garage again because I’ve been working on my R56 but I’ve had the stethoscope on it a bit more and I’m leaning towards it being an alternator bearing noise. The noise is most prominent on the serpentine belt tensioner arm and I can hear it quite loudly in the alternator but I suppose since the tensioner arm, alternator and SC are all connected by at least one piece of metal the sound resonates throughout it all and I can also hear it in the SC and can hear it without the stethoscope most notably from the front of the car (like just behind the radiator) so it makes pinpointing the sound quite difficult. I’m gonna give it a bit of a rest for a while but I’m fairly sure it’s probably alternator but while I’m in there I think I might also replace the bearings in the SC snout. Both of these aren’t cheap nor the easiest things to do but I don’t mind as it gives me something to do lol.

 

is the bushing on the tensioner in good shape?

 

Yeah I just replaced the tensioner so that wasn’t the issue. Even before this new tensioner I had another new one on there that I had on for 6 months so definitely not anything tensioner related since neither of those tensioners did anything for the noise.

 

Have you replaced the harmonic balancer? If not, that could be coming apart. It makes a weird noise when the rubber separates and the two parts start moving independent of one another.
Just a thought.

 

I recently picked up an R53 back in January myself which already had the supercharger service done, and had the same high pitched whistling noise. replaced my alternator and the noise remained, just this last weekend replaced the idler pulley and the noise is completely gone! definitely worth checking out as the part was only $30 and took an extra 10 mins to do while i had it apart for my oil filter housing gasket.

 

Yep, swapped that out for a ATI Super Damper and still no fix :/