I've de-tensioned the belt and it didn't change the noise, so I don't think it's belt/idler/tensioner related. Noise also doesn't change wether or not I push in the clutch. Comes with varying load/rpm.

It sounds like its coming from closer to the middle of the motor.. water pump bearing? it started after I did a clutch job, installed a 17% pulley and serviced the SC


any ideas?

 

Guess you could try and BRIEFLY run the engine w/o the belt on. I say briefly since as you know the water pump is driven off the SC....that would eliminate about a dozen or so possibilities at the front or as some call it, pass side of the engine.

 

PS: water pump internals are made mostly of plastic...I bet it would melt down before making screeching noises like that....

 

The waterpump is driven off the supercharger and some aftermarket water pumps have steel impellers. As you worked on three parts and the noise started afterwards, I would check those and if the sound is coming from the opposite end of the belt, the clutch is a major suspect.

 

Problem is the noise is intermittent :( If it was constant I'd have an easier time with it. Even this time when I caught it on camera it stopped doing it shortly after

 

I have been using a length of PVC hose to locate the source of noise like this since high school. If use properly it is simple, effective, cheap, and safe. Take a length of say 3/8" clear PVC hose about 4 feet long. With one hand hold one end to the ear, and the other hand aim the other end to locate the suspect source of the noise, and move the hose end to follow the increase volume. You want to keep the hand that hold the exposed end a safe distance from the turning machinery, and prepare to let go of the hose on both hands. Even through a valve cover, you can locate if the intake or the exhaust valve/tappet is making the noise.

It is an acoustic stethoscope without the need to make contact.

 

Jack up car
Remove front fender liner pass side.
Remove belt
Hand rotate all pulleys and components with a pulley to check their bearings. Check for smoothness when rotating by
hand, you should find it that way if intermittent.

I for one, would NEVER put a piece of pipe next to my face / head while holding it close to something moving fast, like a wheel or belt...while putting it to your ear, you can't see how close you are putting that object into the path of the belt !

 

I have no idea where you got the idea of a rigid pipe. It would be the dumbest thing to do. The point is using a soft hose.

I would not bring the ear to harm's way to find the noise source, so I bring the noise source to the ear. How hard is that to understand?

 

If you put a funnel on the end toward the engine it would help the noise, similar to cupping your hand on your ear (something I know all to well about having to do).

 

It sounds like the Idler Pulley I just replaced last week on Scarlet.

 

The PVC hose method is the acoustic analog of flexible light pipe - like fiber optic. It allow you to pinpoint and isolate each noise source out of a symphony like in the case of the Mini's drive belt, pulleys, and tensioners. By aiming the hose end at each noise contributor you can hear individually what each one is contributing.

Quite often, a worn bearing or bushing only make noise when it is loaded in a specific way in-situ. Inspecting it by hand without the peculiar load one can miss the deterioration.

 

and the culprit was.... drum roll







the water pump. had some signs of weepage and the bearing sounded ever so slightly rough. I guess the 17% reduction pulley was spinning it faster and made the noise surface? shrug