# Engine hiss



## rhyek (May 21, 2010)

So I took my 2007 2.0 s to the shop today because I wanted to see what was causing a constant hissing noise near the engine. It's only noticeable if I put my ear very close, but the noise is there.
Thinking it might be a vacuum leak I had the shop test for that using a smoke machine, but they claim they didn't find any leaks and that the noise is actually coming from the PCV valve AND IS NORMAL.
Now, I haven't had a chance to go see the car yet, but I've no idea where this valve is, and most importantly if it can actually cause that noise I hear.
Any ideas?


----------



## chimmike (Oct 17, 2002)

PCV is the positive crankcase breather valve. IF the car isn't running poorly, and if there are no codes, there are no problems. These cars have more sensors than the space shuttle now. You'll know something's wrong when that check engine light pops on.


----------



## Faja (Aug 31, 2009)

Pic is a little small but it's where the red dot is and the hose is just above it.


----------



## rhyek (May 21, 2010)

Thanks for the reply guys. So I'm back from the shop after having a talk with the mechanic and basically what he told me is that the valve is working ok, and that the noise isn't really a problem.
In any case, if I want to make sure the noise is coming from there, he also told me I could test it out by just removing the PCV hose and/or valve and just blocking the opening with something. The noise should then cease.
I'm tempted to do this, but should I really be messing around with these things?


----------



## david_2010 (Jul 29, 2010)

Removing the PCV valve would be a bad idea. This little mechanism has more benefits to your car than almost any other component. It returns unburnt gases back into the engine. Removing or blocking it permanently could cause poor fuel consumption, a smog test failure, a persistent check engine light, .. etc. You could take the hose off, check it for blockage, maybe clean it out real good. The PCV valve is made of steel so you can drop it in some alcohol to clean it, and there's one rubber hose sticking out of it. I wouldn't recommend flushing the hose out, just replace it or hit it with an air compressor. Taking it apart may give you some indication as to why it's "hissing". If there is a hairline crack in either the PCV valve, the rubber hose, or the hose just isn't sealing well, you need to replace it. If doesn't sound like your mechanic took it apart to really inspect it though, and probably just "looked" at it closely. I think if you want this tiny issue to go away, take it apart yourself and inspect it carefully.

One trick for finding weird sounds is to take a piece of plastic, or rubber hose about 3 or 4 feet in length (pvc pipe works fine unless its hard to reach), stick one end to your ear and slowly move the other end around where the sound is and you can narrow it down immediately to know if its pushing air out where the pcv valve connects to the hose, or the pcv valve connects to the engine. This can save you a trip to a mechanic when you just don't know what that funky sound is. Go in knowing WTF is making noise and tell THEM what to do 

You can also take some liquid soap and a paint brush and brush the area very lightly with soap. If it's pushing air outward, you get bubbles where the leak is. You typically get hissing when you have air exiting. Now if it's sucking air in, the soap trick doesn't work so well if it's a really tiny hole.. it's just hard to see the soap go in. It's a bit harder to diagnose, but I think you can leave this to a trained mechanic. What he can do is spray the area gently with an alcohol or fuel mixture while the vehicle is on. If the car idles differently (usually it would rev higher for a moment), you have your culprit. It's a lot safer and easier to just spend 20 bucks and replace the 2 parts yourself.

The PCV valve is 10 dollars online, and the hose should be about the same. Good luck.


----------

