Hi All,

New poster here. I have a 2005 A6 with 112k miles (original owner) and over the last couple weeks I've been hearing a sound from the engine bay that I've never encountered before. It is periodic, it doesn't seem to vary with A/C or blower settings being on/off. Not sure how it responds to RPMs (I can test if need be). The best I can describe it as is a brief, repeating vacuum/suction whistle.

In any case, a video is worth a 1000 words so please see attached. If someone could point me down a debug path, that would be excellent

Thanks,
Mike

 

It's probably the Crankcase Vent Valve. It's the round looking thing under under the engine cover. The diaphragm is probably failing in it. With the car idling, loosen the oil filler cap. Try to slowly remove it. If it feels like it's being sucked back onto the filler neck, the crankcase vent is failing. Also if removing the oil filler cap makes the noise go away, that will also point to the crankcase vent. Here's what it looks like. Easy fix too.

http://www.partsgeek.com/catalog/200...ent_valve.html

Yours should be the second one down the list.

 

Thanks so much! I removed the oil filler cap slowly and it was being sucked backed onto the neck. The tone of the noise changed as I removed the filler cap as well.

I'll be ordering a new crankcase vent - thank you again for this info.

Mike

 

Hi All,

I finally had a chance to attempt to fix this problem today so I installed a brand new crankcase vent valve - the exact one in the post from Dave944. The valve went in fairly easy - but - still I hear the same noise as in my original post.

The noise seems to be focused towards the front of the engine - near the lower left side somewhere.... but my hearing isn't 100% so take that info with a grain of salt.

Any ideas on the next course of action? Does anyone have a breather & vacuum system diagram they could share?

Thanks,
Mike

2005 Audi A6 Quattro

 

Man, I could have sworn that would have been a crankcase vent leaking. At least it's a cheap and easy repair/troubleshooting step. Try this. Get a can of spray carb cleaner. Crank the engine and spray (not soaking spray but more of a little brief squirt) around the hoses that you can get to in the area your hearing the noise. If you get a change (up or down) in the idle speed of the engine, where you just sprayed is where your leak is located because it will be sucking in the carb cleaner (adding fuel). Carb cleaner will evaporate very quickly but be careful with it.

Is the check engine light on?