okay, i have a 2005 cobalt ss/sc. for the last few weeks i have been getting a ticking noise when i first start the car. two days ago, she was hard to start, and then she developed a hissing (squealing) noise under acceleration. i was hoping it was the ac compressor, but it seems to be something else. also, she experiences a loss of power, and her gas milage is gone to ****. the check engine light was always on ( i bought the car used), and that was an oxygen sensor, but now the fuel consumption has gone from 9.2l/100km to 11l/100km....? if anyone could point me in the right direction, that would be great. Thanks

Also, if someone could tell me where the timing chain tensioner is, i would appreciate it

 

Take it to your dealer if you still have warranty first of all.

If you bought it used it sounds to me like it might be in need of a major tune up.

 

it is in need of a tune up, i know that. i just took it out of storage 3 weeks ago. she has 63000km so she is just out of warranty. the hissing noise is what concerns me the most. it only happens under acceleration, and seems to idle fine. i should also say that the ticking noise goes away once the car warms up. i am thinking there may be a vacuum leak, or a leaky intake/supercharger gasket...?

 

timing chain / tensioner?? there is a recall on those things...

 

If the hissing noise gets louder as you accelerate then most likly a exhaust manifold leak or where the down npipe joins on to it.
Where does it sound like its coming from you werent to specific ?

 

it sounds like its coming from the belt side of the engine, but its hard to pinpoint the exact location. the alternator has crossed my mind as a possible cause, as has the ac compressor. but the loss of power during acceleration is what bothers me. it seems like she is starved for fuel under acceleration, past a certain point on the pedal. either that, or loading up on fuel....

 

If its a timing chain issue , your powertrain warranty should still be good , its 6years 60000 miles in the US for 05 and 06's.

 

i'm gonna say it's an exhaust leak.. went from a ticking on start then hissing .. sounds like a leak.. i h ave one and thats what it sounds like

 

exhaust leak...prob. a clogged cat or vacuum leak

 

Well, friends, i found it. exhaust manifold leak. thanks for all your suggestions. you have been very helpful. I was scared to **** it was the engine. what a relief! I did swap out the plugs and air filter as well. they were in rough shape.

 

good deal.. no problem.. i drive with one every day .. haah i need to get it fixed

 

god, its too annoying for me to drive. it squeals like a pig under hard acceleration. at least its not an expensive fix. couldnt really get in there to see if the bolt was loose, or the gasket gone, or the manifold cracked. either way, its better than an engine replacement.

 

true it's alot cheaper.. me i know what it is.. the weld i did when i reflanged my catback isn't fully penetrated.. so theres a small hole... mines not that bad.. i get a little poppy hiss noise coming from it though .. it's annoying but it's dealable