Wife said there was a grinding noise today when she started the car so she turned it off and waited.

When I start the car, I don't hear a grinding sound but after I shut the car off, I can hear a cough cough sound like a little backfire or valve opening/closing from around the area of passenger side of engine and there is a chemical smell that I can't identify??

Any thoughts appreciated.

Year,engine? It helps..

It rhymes!

A loose air intake hose or air filter housing could make noise.

Could you elaborate on the chemical smell?

05 Outback. 120k miles. Auto.

I guess I've never been under the hood when I turned the ignition off so I wasn't sure what "normal" was.

After the car was driven for a while, it didn't make the "cough cough" when I turned the key off.

I drove it to a buddy who is a Lexus service manager and after listening to the non-sound first questioned my sanity then questioned whether the smell was noticeable since I was starting and stopping the engine while in the garage (yes door was open).

Anyway, I checked my 08 Outback and it makes something of a similar "cough."

It seems to be coming from the passenger front side on both cars.

They are garaged together. Perhaps the cough is contagious.

I'll try to do an audio capture tomorrow and post.

Sounds like a type of "pre-ignition" or "dieseling". The poorly burned gas will give off an unusual, and distinctive, odor. I think that this was a lot more common when cars had carburetors. I AM TAKING A GUESS AT THIS PROBLEM BASED ON THE DESCRIPTION. I have never read about a Subaru suffereing from dieseling. Anyway, if it is dieseling , make certain that you have the proper spark plugs installed. Carbon desposits in the cyclinders can also cause dieseling.

http://www.youtube.com/watch?v=FAYcT4uhytg&feature=youtu.be

:popcorn:Grab your popcorn and head on over. The sounds aren't produced as clearly as I had hoped but what I am referring to is the final 2 coughs of each start/stop cycle recorded.

As stated earlier, it doesn't make the sounds once the car is completely warmed up.

A/C clutch?

 

I dunno

Once again, this a just a guess. But, to me, it does sound like a very minor amount of dieseling, maybe one or two ignitions. There may be a small amount of residual unburned gas in one or two of the cylinders after start up, just enough to support a small combustion after the egine is turned off.

When cars had carburators, some engines would diesel for minutes after the ignition was switched off. It was something to see, and the poorly burned gasoline gave off a very peculiar odor.

Once again, this a just a guess. But, to me, it does sound like a very minor amount of dieseling, maybe one or two ignitions. There may be a small amount of residual unburned gas in one or two of the cylinders after start up, just enough to support a small combustion after the egine is turned off.

When cars had carburators, some engines would diesel for minutes after the ignition was switched off. It was something to see, and the poorly burned gasoline gave off a very peculiar odor.

 

maybe pull plugs to see if one is wet?

Lean make them smell funny feul pump not making enuff preshure pluged fillter pinched line. Or did somone put deisel in it { dont laff twice thiss year } had cars with deisel in tanks try and diagnose that pain in rump roast.

That is strange for sure. Dieseling in gasoline engines usually occurs when the engine is hot or if the ignition timing is way off. And at that, you have an electronically controlled ignition system which should not be creating spark once the ignition is off. The proper lean mix of fuel with just enough compression will combust on its own with no spark.

 

I would suspect a leaky fuel injector at the least.

Well, I now have heard the same sounds on my wife's 05 OB (subject of this post), my daughter's 05 Legacy and my 08 OB. I have to assume that this cold start/stop sound is normal. I am bringing it in for a free (Lifetime) oil change and will ask the tech to identify the sound.