I recently got my oil changed and about a week or two later I started to notice that my engine was louder than normal. It had started to produce a "hiss" or "buzz" that IMO is common to an old beater car that isn't in the best shape. I'm at 76,900 and while my car isn't brand new, I know what it sounds like and this for sure came out of nowhere.

The sound occurs constantly throughout acceleration with the motor hot or cold. I have tested with the hvac on and off and the noise doesn't go away. I can even hear it over the radio if it isn't cranked.

I took my HHR to the dealership in hopes that they would find a leak of some sort but they couldn't find the issue. My vehicle had already been there for 2 days for them to tell me that so I decided to take it to another dealership where I was told the same thing. I rode with a technician and he didn't see the sound as a problem and he couldn't even begin to tell me what might cause the sound to just appear out of nowhere like it did.

Does anyone have any ideas? Could the new oil from my oil change cause this? I am tempted to get another oil change just to troubleshoot.

 

My money is on that they checked your air filter and didn't resecure it correctly.

 

Great idea! I was already planning on checking and maybe replacing it this weekend along with the cabin filter. I will post up my findings. Thank you

 

Well I called to ask them if checking the filter is something that they do and the Shop manager told me it wasn't part of normal procedure unless it was requested by the customer.

It's still a good starting point for troubleshooting.

 

Air box hose could still be loose, regardless of if its standard operating procedure.

 

I feel like the dealership should have been able to find it in 5 minutes. Have you checked your oil level, just for the hell of it? Doubt it has anything to do with that.

It sound likes it could be an air leak. Have them re-secure it REGARDLESS of normal procedure on the prior work it received. Have you tried to pinpoint the sounds location yourself at all-as in popping the hood and giving it a listen?

 

Another possibility once the airbox is checked for proper installation is a cracked down pipe leading from the exhaust manifold, if they break you will get a commotion close to what you's hear from a loose airbox.

 

A cracked downpipe/flexpipe would sound like a hiss and tick. Does it tick? You should also get a code.

 

Flex pipe............ and you may or may not get a code, but you will get the noise.

 

I had the oil change tech at my dealership forget to cap off the top of the block a couple times.. made a hissing/tick sound.