2006 Colorado I5 engine noise

[HaroldCallahan]

On my 2006 Colorado with I5 with about 1800 miles I notice a hissing like noise from rear of engine on drivers side. There is a hose going into the back of the plastic housing on driver side. Appears to be from the hose inside the housing. I put a rag around the opening in the housing where the hose goes in and the idle speed dropped.

 

If it is normal then I dont want to take it to dealer.

 

On other hand if it is a problem then I want to know before I take it in, so I will know what to say if I am told "it is normal". I am concerned that this could be a loose hose connection somewhere under the housing that I cannot see , causing a vacuum leak. This might cause a lean condition or be sucking dirt into the motor.

 

Also I notice a whining noise coming from front of engine, not at idle but when engine speeds up. Not like a slipping belt, but more of a whine or whirring noise.

 

Any information on this will be appreciated.

[GM-Tech]

Is the hissing noise constant? This may be just normal air flow within the plenum, but it's really hard to say without hearing it.

 

As for the whine... we had a problem with timing chain tensioners making a whine noise, but that was only in 2004 Colorado and maybe a few early 2005's. Almost every one made that noise, some barely audible, others pretty loud. I have an '05 Colorado and it made that noise too. I just drove it because I knew it wasn't a problem, just a noise, and not that loud. Now that I have some miles on it, the noise appears to have gone away.

 

So while the whine problem was supposedly fixed in 2004, it's possible this could be what's making your noise. Again, without hearing the noise and diagnosing its source, it's hard to say for sure.