OK, two weird noises started happening lately, the first one came first a few weeks ago and hasn't gotten worse, but the second one just started and is getting worse quickly. 1) When engine is running, it sounds fine, however when I rev it a bit, it sounds fine going up in RPMs, but on the way down it makes this weird hissing noise like a hose spraying water with one of those nozzles. There are no noticeable leaks under the car. 2) This is the weird/alarming one...when I turn off my engine, it makes this really loud creaking noise like a really old rusty door hinge slowly creaking open. It's been getting louder, and the longer I run the car the louder it is when I turn it off. Any thoughts?

My car seems to be running fine, accelleration and everything else-wise, but lately it has been getting TERRIBLE gas mileage for no "regular maintenance" reasons (I changed the oil+filter, air filter, fuel filter, MTL, all with top-notch stuff less than 500 miles ago). I am talking barely 200 miles per tank. And these tanks are HUGE! I calculated like 15-17 MPG or something, half city half highway, and I don't usually drive it that hard.

Also, don't know if this matters, but I just got a new alternator installed about a week before this started happening, I think my stereo killed the first alternator ('bout 1000 watts from 2 amps.) I went with a new stock alternator, couldn't find a reasonably priced aftermarket one that was noteably better. Could something be wrong with the new alternator causing any of this?

 

No one has any suggestions?

 

the creaking door sounds might be the lil elves getting into the engine so they can work the cranks and pulleys to get the car moving......damn keebler elves......
as you can tell i have no clue what i could be....

 

Vacuum ... leak ?

 

No Check your belts and your Tensioner. I remember I had a cricket sound in my engine one day out of no where and well it didnt get worse but two days later it turns out it was the Tensioner. It shattered on my way to a Junk yard with a friend. Had to get my engine rebuilt. And 1500 dollars later. Its fixed. So please I beg you get your tensioner checked out and the timing belt. Thats what could be going. I had the same noise you had. And I thought nothing of it and right now Im paying back a fat loan because of it. So get your car to a mechanic and check that tensioner and timing belt soon.

 

Ps when I was driving to the junk yard my car started loosing power and gas mileage was starting to suck as well. My mph were dropping even though my foot was at the same spot and then the unevitable. The engine made a weird noise and stopped and I coasted to the side of the road luckily with my steering wheel locked in that direction with barely any brakes. It was scary.

 

That's your blow off valve, mine does it too.

 

Actually my JWT Intake makes a sound a lot like a BOV, but this is much scarier, it sounds like when you spray an aerodol can, and its constant all the way down to idle when you take your foot off the gas.