I have an 04 MCS with a 15% pulley, ALTA CAI, VGS mod and MTH software. Ever since the pulley install, I have had a squeal that shows up in cold weather when I first start the car.

The squeal is not heard at idle, but is heard when the engine is revved (under load or in neutal), most notably between 2500 and 3200 RPM. In the summer, I don't notice it at all. But in the winter it's impossible to miss.

It has gotten louder since last winter, which caused me some concern. But the belt appears to be in decent condition. (I should mention that I did swap out to the slightly smaller belt shortly after the pulley install in an effort to get rid of the sqeal, which did not make any difference).

My dealership won't really look at the cause of the squeak, since there is an aftermarket pulley involved. So I'm hoping someone out there can help me figure this out.

At first I just assumed it was just some minor belt slippage, but figured if there was no damage to the belt showing up, it was no big deal. But now that it's getting louder . . .

I'm also starting to wonder if there is any chance that the supercharger shaft is slipping inside of the aftermarket pulley? This could explain why the slippage takes place in cold weather (SC shaft shrinking more in the cold than the pulley?).

My pulley is one of Randy Webb's polished numbers (not the ALTA, but similar design and from Germany I believe?). Randy did the install, so I am pretty confident the install is not the problem.

Anyone have thoughts?

As always, thanks to the awesome MINI community for helping me deal with my obsession.

NTHUSIAST

 

I was going to suggest the shorter belt, but you already have it.

Try comparing the tension exerted on the belt by the idler pulley to another MCS. Perhaps you have a weak spring in there.

Also, try some belt dressing spray from the auto parts store. See if that makes an impact.

If all else fails, remove the belt and really inspect the various pulleys and make sure they aren't glazed. Also check the idler pulley and make sure the bearings aren't worn out. Sometimes they can make quite a racket.

Let us know what it is when you figure it out.

Rawhyde

 

Is it doing it when car is in neutral .I had a squael that dealer thought was belt in ended up being something else.

 

Thanks for the repsonses.

It is definately only cold start and RPM related. Happens in neutral or in gear, under load or not, clutch in or out.

I tried the belt dressing trick a few weeks ago, and it didn't help. I haven't really wanted to rip into this thing, but I suppose the time has come. I'll have to track down a belt tensioner tool and pull the belt off, inspect the pulleys, the belt etc.

Any chance my theory about the shaft slipping within the new pulley could be accurate? Anyone have other ideas?

Thanks again,

NTHUSIAST

 

Sounds like the belt tension pulley bearing has gone south (for the winter) .
Seriously, get yourself an automotive stethoscope. Have someone rev the engine to repeat the sound while you fish around with the probe end. You will find it no problem. I'll bet it's the tension pulley.

 

Most of those aftermarket pulleys attach to the shaft like an industrial pulley with a device similar to a "taper lock" or a "QD" bushing. Unless the attaching bolts are EXTREMELY loose, I doubt that's where the slippage is.

In industrial applications, once a belt has been really squealed, it is ruined. It'll never grip well again. I bet you've glazed the belt. If you replace the belt and all is well for a while, then it does it again a few months down the road, try a belt for a JCW car. They are a tad shorter and will keep the tensionser in its sweet spot better.

 

I have the same issue, but it goes away as soon as the car warms up... wouldn't belt glazing cause the squealing to keep going even when warm?

 

I'm having a similar problem. I get a squeel, birds chirping, whistling type of sound at a certain RPM and throttle position(usually 2000-3500RPM). If I increase the throttle just a bit it will go away, or if I let off it goes away. It does it when the engine is cold and warm. It was very faint when I had the stock intake on, so when I brought it into the dealer they said it made "normal sounds." Now I put the Alta CAI on and it is pretty obvious. Anyone have any ideas? I'm due for my first oil service soon so I will have them look at it again. I don't have any pulleys on either. It's all stock so I don't think it would be a belt or pulley issue, although you never know.

It's not the supercharger whine either...I know what that sounds like and this is happening before that kicks in.