Hi all after trying to change a cooler duct on my 4.2 I gave up and have ordered more parts so I can do both banks together.
As it was a fairly minor vacuum leak I put it back together so I could carry on driving it but I have a horrendous noise now and have no idea where to start? Any help would be grateful as I am really worried...


 Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

I meant to also say this hose had Popped off I think when I looked earlier on - would this cause that sound or am I dreaming - hopefully someone has some ideas I can look at this eve cheers

Hard to tell, but it sounds like a dry bearing.

Can you pinpoint where the sound is coming from? Current:
- 2017 L405 3.0 V6 Autobiography
Sold:
- 2013 L405 4.4 TDV8 Vogue
- 2004 L322 4.4 Vogue (BRC LPG)
- 2002 L322 4.4 HSE (having fixed timing chain guides)
- 2000 P38 4.6 Vogue (BRC LPG)
- 1981 2-door In-Vogue
- 1980 Ex-Army SIII LWB
- 1976 SIII LWB
- 1968 SIIA
Stripped for parts:
- 2003 L322 4.4 Vogue

Got the little hose on at lunchtime not sure if It’s any different

Bearing idea sounds good but it didn’t do it until I took the plastic intake offf and the supercharger ducts?

 Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Yes sounds like a bearing, maybe one of the beld-tensioner-bearings.

You are going to need to pinpoint the noise - I find a GS (giant screwdriver) helps in this regard.

Stick the handle in your ear and the tip at various locations. You should be able to pinpoint it fairly accurately.

Would you drive it or park it? Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Depends on where the noise is coming from. Either way I wouldn't drive it, if one of those bearings stops then it will tear the belt and none of the auxiliaries will work. Best bet it to try and listen to where the noise is with a long screwdriver. Hopefully it's just a tensioner as they are a common thing to go.

Ok so to anyone it doesn’t sound like a knackered supercharger or anything like that? I was wondering if i have a vacuum leak what the out of amplified sound coming from there are? Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Could be a bearing in the supercharger. Really easy to fix. They don't go wrong that often so I would start by isolating the noise. Take off the auxially belt and see if the noise it still there. That would tell you if it's the supercharger or not.

I once left a washer on one of the studs between head and intake manifold on my girlfriends Porsche 944. It let air in, and made the gasket vibrate like the tongue in a instrument. It made such a noise I think all our neighbors heard it! I thought a bearing was dying first.

You can use a pipe to listen for the sound, one end by your ear, the other end scan for the source. 2006 Supercharged

Ok - an update

Parts arrived yesterday so last night armed with a torque wrench the workshop manual and the parts I followed everything to the letter and it looks like that’s what I had actually done initially whilst I was going through it.

I changed the two gaskets and the elbow gasket to the supercharger.

I then too a photo of the charger with the elbow off is there anything to be worried about here...? No obvious debris damage?

Just a wild stab in the dark, but have you checked the oil level in the supercharger?

And again, try to pinpoint the source of the noise with a GS or similar - supercharger, all the stuff down the front of the engine - water pump/fan, aircon, steering pump, idler etc. To eliminate the SC, you could remove the drive belt for it.

I tried the screwdriver but was trying to do fairly quickly as don’t like the noise as don’t want a serious problem - how can you check the supercharger oil level I saw a refill guide but is there a way just to check the oil in it?

I did think next stop supercharger belt off and go for a short drive if the sound goes and if it doesn’t serpentine belt off and just start and run it for a minute or two?

Are my long term fuel trims at idle still indicating a vac leak or will they take a while to readjust? Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF

Are your ltft plus 22?

If so you still have a large vacuum leak and that'll be the source of the noise