03 MCS (dec 02' built) Stock - no mods.

I been digging around trying to find threads with noise issues and have come across the supercharger/waterpump issue, the steering pump/fan issue but neither of these seem to be associated with my new noise which started 2 days ago. There are two sounds and they both are distinctively associated with RPM. As RPM goes up they both go up and vise versa.

Sound 1 is whine, like the whine you would hear from the sterring pump when turning the wheel, but much louder and defined.

Sound 2 isound like a loose washer on a bolt rattling, however it also increases and the pitch become higher with RPM.

At idle Sound 2 is vaguely audible and the Sound 1 is not audible at all.

Both sound are coming from the engine bay aroung the belt area, but can not pin-point it.

I am thinking something attached to the belt is making the sound but i am not certain. My guess of the top would be the alternator as Sound 1 really sounds like and electric motor.

No parts in the engine bay have been replaced other than AUX fan assembly (not the sound make)

I have as sound file of Sound 1 (sound 2 not audible due to other noise/static) is abt 83kb, but i can not see how i can post it (it's and .amr file).

Any suggestions are welcomed.

 

Check the Crank pulley. That's were my rattle came from.

It was redesigned after 2003.

 

Turns out, its most likely the supercharger. According to a friend, who suspects the bearing inside the s/c is worm which can cause both sounds. Looks like I have to either get a new one or try the refubished swap that being offered here on NAM.

 

Also look at the belt tensioner.. it has a metal strip in the spring. Sometimes on the higher mileage cars you can see this tab rattling inside the spring causing a noise similar to what you described. Good luck. hope its not the SC.

 

Noise solved.

Soooo I have taken the front off, bumpers, crashbars, intercooler all the way down to the Super Charger, removed it as well, took off the waterpump, it looks good, checked the super charger cowls? they look super, no chips in the coating (teflon?) opened the front and back oil plugs on the s/c and both had normal levels with clear fluids. Spun the charger with a drill hookup to a bench using the old belt (ordered a new one since the car is apart) no abnormal noise. Neighboor came by next day, and hand spun the idler pulley and the tensioner pulley and....the tensioner pulley makes a noise and woble slightly on the bearings....like suggested above. The easy way would have saved me a lot of time, but at least i got to inspect my s/c, w/p, etc.

BUT in the heat of ripping MINIDK apart i broke the PCV hose locking clip on the super charger. I can for the LOG not find this part number anywhere. It the round locking ring that sits in the s/c and the grey, stiff PCV hose fits in it. Does anyone know the part number?

BTW i am ttl newbie on cars, did my first brake rotor change on MINIDK, so i am pretty excited that i was able to dismantle the front end. Now i just have to put it all together, hope i dont forget eanything and align the front bumper... gotta love the Bentley Manual.

 

UPDATE:

Put MINIDK back together after installing new tensioner pulley and idler pulley (since I had the whole front apart). The noise is no longer there!

I also replaced the AUX fan (had the known aux fan die/battery drain issue). I nopticed the AUX fan does not come on after i started MINIDK up. Is this normal?

Does the AUX fan only come on in low sppeed when needed and then switch to highspeed when it gets really hot (sommer afternoons in Houston)?

or should the low speed always be on, even at idle/coldstart.?