Hi, I am hoping that some one can help.

About 2 weeks ago I developed a boost leak and at the same time (maybe just a coincidence) started to get what I can only describe as like a squealing / chirping high pitched noise when in boost.

I had a leak on my aftercooler which has since been recitified and I still have the noise. I thought it was the dump / recirulating valve so have replaced that and still have the noise. The s/c belt is tight, there are not any noises when not in boost as in if I rev the car hard at standstill. There is no play in the shaft in the s/c itself and the SOS s/c pulley has only done around 2500 miles and I am guessing that if it were bearings in that pulley I would hear it all the time? I have had a smoke / pressure test so I know that I have not got any more leaks, i.e. every thing is done up correctly and I am now out of ideas as to what on earth this noise could be??

We had not done a great deal of WOT tuning when this noise developed so am now beginning to wonder if this noise is normal and am I being paranoid?

Ideally what I am after is a video or sound clip of a Novi 1200 blower on full boost from 3,000 to 8,000 rpm in 3rd gear so I can compare it to mine. If you don't want to share your video clips on here please PM me.

I have not got a good enough video clip of mine to post up and don't want to push the car in case I am doing any damage.

The car is due to go on a rolling road this coming weekend so that we can get our head's under the bonnet in an attempt to see & hear exactly what is making this noise when in boost and what I don't want to do is waste time chasing some thing that may be normal - although I do not believe that this is normal - some thing is not right some where.

Has any one got any other suggestions as to what this may be? Difficult I know without a sound clip from me but all ideas & suggestions are welcome.

Can some one help me out please?

 

You're having a fecking nightmare with the install arn't you bud.

Hope you get sorted soon

 

James, I would say rather than nightmare

 

Did you inspect the tensioner pulley for the SC?

 

^^^ Yes I was just thinking the same thing, check the tension/idle pulley, make sure the bearings are not going out on this. Isolating the sound is key, make sure it’s not something else. You can drive the car without the blower belt to see if by chance your still getting the noise without the blower spinning. But I would check the idle/tension pulley first. The belt will already be off after this anyway for testing.

 

Just to clarify - the noise is only there when the car is under load / boost and is not there if I rev the car hard stood still

So questions:

How will I know / be able to tell if the tension / idle pulley has had it?

If it is the bearings would I not hear them all the time?

Is the noise I am describing the typical noise you would hear when the bearings in the tension / idle pulley have had it?

The kit has not done many miles so can something like this be worn out already?

I'm assuming that the bearings in the tension / idle pulley can be replaced if it is them or am I better to replace the pulley?

The noise is definitely not there when not running boost so it has got to be something to do with that.

More importantly will I do any damage if I drive the car like this, i.e. is the pulley likely to seize and if so what are the consequences?

As mentioned above I am due to go on a rolling road this weekend to get the car fully mapped and to identify this noise as obviously you can't put your head under the bonnet of a moving car but you can when it's on a rolling road.

Am I best delaying the rolling road session if the tension / idle pulley is causing the noise as will 400+bhp going through it kill the pulley all together and end up in some serious damage to the s/c?

 

If it was the idle pulley or blower bearings I would expect to hear it at all times. If the idle pulley does fail, the worst that will happen is it will seize up and your belt will burn up and come off and the pulley will be damaged if its plastic, likely no damage will occur to your blower. You can take the idle pulley off and spin it in your hand, feel if there is any notchiness or a lot of play in the bearing. Typically you would just replace the whole pulley, not just the bearings, if you have the stock plastic pulley then the bearings are pressed in and not really serviceable. The whole pulley with bearings is only like $25 -$35

 

Are these pulleys widely available or are they SOS only given that it is a part of their kit?

Any suggestions as to where I can get one?

 

Here you go:

Dayco 89017 Tensioner & Idler Pulley

 

$35 / £23 delivered to the UK from Amazon - bargain

Got to be worth a try