2010 ZR6 engine noise, belt side

[AurionZR62010]

My Aurion is a 2010 ZR6, I've got an intermittent rattling noise coming from the belt side of the motor.  I've replaced all three pullies, the A/C compressor and new belt installed.  I've checked the water pump, all seems fine there, I'd replace that too but it appears to be a "challenge" to remove and replace, we don't think it's coming from there.  The alternator has 100K on it, replaced three years ago.  Like I say, it's intermittent, but when it happens it sounds BAD.  When I rev the motor there's a "whoosh" noise and it goes away.  It's really hard to pinpoint a scenario that makes it happen.  Motor itself is in good shape, no sludge, plenty of power.  300K freeway kms.  Any ideas?

[fortydegrees]

Sorry it's not a solution reply but I also get a short intermittent rattle on start up when car is almost cold. I've managed to isolate it to when the coolant needle is sitting maybe half a cm above cold. Doesn't do it when dead cold or at operating temp and doesn't make any noise at all when driving, just on start up. Half a second it's gone, sounds like a pulley to me so interesting to hear you've replaced pulleys with no success.

Some on here have said that VVTi gears or something to that effect can cause a rattling noise on that side of the engine. I'm not 100% certain of it is that how bad it is if these engines do have noisy VVTi gears. Sorry I couldn't help but if you do some searching on the VVTi thing you might see if it's a similar noise.

[Tony Prodigy]

On 6/21/2023 at 3:51 PM, AurionZR62010 said:

My Aurion is a 2010 ZR6, I've got an intermittent rattling noise coming from the belt side of the motor.  I've replaced all three pullies, the A/C compressor and new belt installed.  I've checked the water pump, all seems fine there, I'd replace that too but it appears to be a "challenge" to remove and replace, we don't think it's coming from there.  The alternator has 100K on it, replaced three years ago.  Like I say, it's intermittent, but when it happens it sounds BAD.  When I rev the motor there's a "whoosh" noise and it goes away.  It's really hard to pinpoint a scenario that makes it happen.  Motor itself is in good shape, no sludge, plenty of power.  300K freeway kms.  Any ideas?

Sounds like the dreaded VVTI rattle.  Did your mechanic shot gun replace all those other parts mentioned without doing a proper diagnosis ? Pretty expensive way to diagnose a problem that's for sure.