N00b question - what is this?

[garethcayman]

Hi Guys,

I've bought my first Cobalt with Mercruiser 496 mag a couple of months ago and still getting to grips with this 8.1l beauty.

Replaced my first serpetine belt and two idley pulleys... feeling like a hero!

I took the cover off today to try and find the IAC and was wondering what this is? Is it an Air filter? Mine is so dirty

Anybody got any tips on how best to clean?

[Titaniumboy]

While I suppose it might do some minimal air filtering, its main purpose is as a flame arrestor.

Looks like yours is clogged up with a good portion of the serpentine belt. It is easy to remove. I would try blowing it clean with some compressed air, but be gentle.

While the flame arrestor is removed, see if the IAC Muffler (a tiny $2 piece of foam) is still in place and in good condition. If it is missing or deteriorated, your engine will have a loud whistling sound.

[garethcayman]

Thanks for the tip.

I removed, cleaned and refitted. Engine is starting first time now and not stalling.

re: IAC muffler - it looks to be in place but is completely black? I'm going to order a new one to be safe. How long do they normally last?

While I suppose it might do some minimal air filtering, its main purpose is as a flame arrestor.

Looks like yours is clogged up with a good portion of the serpentine belt. It is easy to remove. I would try blowing it clean with some compressed air, but be gentle.

While the flame arrestor is removed, see if the IAC Muffler (a tiny $2 piece of foam) is still in place and in good condition. If it is missing or deteriorated, your engine will have a loud whistling sound.

[Titaniumboy]

I have no idea how long they last. I happened to be talking with Cobalt Chat member baktasht last year about adding a real air filter to the air intake. I mentioned in passing that my engine had a loud whistling - actually more like a wheezing sound - that was really noticeable when the engine cover was open. He offered the opinion that my IAC muffler was missing or deteriorated.

First time I had ever heard of such a thing. I bought and installed the little goofy piece of foam and , sure enough, it solved the engine wheezing problem. I later took a closer look at my Merc Owners manual, and found a section discussing the IAC muffler. The owners manual pictures were not very good and I would never have guessed they were talking about a piece of foam without the help of baktasht.

Kind of amazing that so much sound would be coming from the IAC valve back into the air intake. Even more amazing that a little piece of foam stops all of that sound.