Supercharger worries - squealing noise?

[Alexander 0]

Hi guys, here's the deal;

 

I've got a lightly-ported charger in my G60 that was rebuilt about 25,000 miles ago by PSD. It's running a 68mm pulley so I suppose it's due another rebuild shortly.

 

Since I've had the G60, it's always made a high-pitched beep/squealing noise at high boost (really flooring it), I've posted a thread on here about it before but nobody could put their finger on what it could be. Over the last few months a new interesting noise has developed - a high-pitched squeal at part throttle, seems to occur at just under 0 bar boost then goes off if you continue to press the accellerator (you can make it go *squeal* *squeal* *squeal* if you prod the loud pedal under load if you see what I mean).

 

My first thought about the part-throttle squeal is that it's a belt slipping, but I recently had the charger belt changed for a new one of the correct length for the pulley (shorter belt) and it made no difference.

 

So I suppose my question is - could both of these squealing noises be coming from the charger itself? They both seem to be boost-related, but I'm not sure what noises a charger makes when it's on it's way out. I always thought the 30k rebuild schedule was a recomendation to avoid problems, rather than the period at which they start to break. The guy who I bought the car off said he never drove it hard, and I certainly don't, so it's had an easy life since it's last rebuild.

 

Cheers for any input guys! :)

[flusted 0]

sounds just like the boost being re-circ'd, iow corrado g60s did this.

 

Shame new owner is bouncing it off the limiter in this vid but you should get the idea of the noise

[flusted 0]

40k rebuilds on 68mm pulley aswell i believe

[Alexander 0]

Hmm no that's a squeal on the overrun, this is 1) part way through the boost and 2) at a certain point at high boost. The initial one sounds like a high pitched squeal (very much like a belt), and the top one is almost like a "beeeeeeeep".

 

And yes, you're right - 40k service interval on a 68mm pulley.

[flusted 0]

maybe loose or leaking hose on the throttlebody? idle screw missing or something? car making good boost?

[Alexander 0]

I'll check all the hoses thoroughly tomorrow, good call. Car is making great boost, behaves very well and feels strong all the way through the rev range. It's really weird, but you kind of know what noises it should and shouldn't be making, you know, and I'd rather get it sorted if you see what I mean!

[DANG60 0]

Hi mate, do you have the boost return deleted? Ive got mine deleted as im running a bbm screw charger and mine does this. I think its just the transisition when on boost from the flap being partly closed to fully closed. So in effect the boost is escaping until the boost return flap is fully shut. I dont have any boost leaks either

[JMC 0]

Could be the tensioner pulley - when was that last changed?

[Alexander 0]

Hi mate, do you have the boost return deleted? Ive got mine deleted as im running a bbm screw charger and mine does this. I think its just the transisition when on boost from the flap being partly closed to fully closed. So in effect the boost is escaping until the boost return flap is fully shut. I dont have any boost leaks either

 

Yeah I do have the boost return deleted - that sounds a pretty reasonable explanation, although I don't remember it always doing this?

 

Could be the tensioner pulley - when was that last changed?

 

Well the cambelt was changed late last year, not sure if the tensioner pulley would have been part of that work? Is it a major problem if that's the cause?

 

Thanks a lot for all your suggestions guys! Much appreciated!