[liquidether]

Hi guys, I think this may be my first post though I've been coming here for a while for answers. Great forum! I'm not sure how to look for what's going on because I'm not sure what's going on.

I think there's a leak but I'm not sure if it's a normal sound or not. I noticed a whistling noise the other week and thought it was a car next to me. Turned out to be me. I popped the hood after I got home and felt all over the place while the engine was running. When my hand passed over what I think might be a throttle body enclosure the hissing noise lessened.

I narrowed the noise to a little hole (looks like it's a hole designed to be there) on the side of a black box on the rear of the engine.

The little hole (1/8"?) is on the passenger side face of the box, right in the middle and if I cover it with my finger the engine starts to rev really high, when I uncover it the engine returns to it's normal idle, whistling while it works.

Any ideas what this is? Maybe it's normal, maybe it's not. Either it's getting louder or I'm just noticing it.

Thanks!

 

[aubrav]

Did you ever figure out what this was? I am experiencing the exact same symptoms.

Thanks!

 

[canoewnc]

Mine is an 05 and looks different. I have a heated PCV value sitting where you have the VW emblem. It has a hole, that sould not leak, they do tend to fail. It does connect to the back of the valve cover and other small vaccum line at the back of the motor. At the back of the motor are a ton of small vaccum lines. I swapped motors last winter and replaced all the lines. Almost every hard plastic line was splitting open, where it was attached to a fitting, even the vaccum line for the brake boost, behind the firewall.

 

[canoewnc]

V-6 ready to install

The photo shows my V-6 ready to install, you can see all the lines on the back corner. The intake and throttle body are not installed. My PCV goes to the hole in the top back corner of the valve cover, above the timeing chain gears. It could easliy be one small vaccum line broke, they are hard to see and hard to reach. There are three vaccum lines in the top bundle all inside one black plastic sleeve.

 

[canoewnc]

V-6 Closup behind Thottle Body

This photo is of the junk yard replacement motor, before I tore it down. I picked up a newer V-6 with only 42,000 to replace my V-6 with 116,000, which had a couple bad roller rockers. The Throttle body is removed, with tape on the intake. The black plastic line from the PCV value to the valve cover is broken. You can see the vaccum line going to the EGR valve, and two additional small vaccum lines related to the throttle body and PCV value. So hidden in that back corner on your 07 probalby has several small hard to see vaccum lines. They are plastic and due to the location and engine heat, get brittle and break easy. I know mine is a different year with a slightly different setup, but hope it helps.

 

[dwb2013]

How did you make out with that vacuum leak? I'm having the exact same issue with my 2007 Touareg, I cant seem to figure out what is supposed to be in that hole.

Thanks.

 

[canoewnc]

Vacuum leak

My PCV value has a little hole, on my 05, nothing goes in the little hole. It is a vent so the vacuum diaphragm can move. If air is getting sucked into the hole, then the diaphragm has failed. It limits the amount of crankcase ventilation. Plug a vacuum leak and it should idle higher, but not reve up. 07 might be different.
Don

 

[allglobal]

I have a 2010 Touareg and have the same issue. Local mechanic wanted to change the entire pcv valve cover at around $1200. Brought it back and ordered the diaphragm membrane for $25 on ebay. Will change it in a couple of days. While I do that, I will perhaps change the spark plugs too.
Anyone has any idea/word of advice when I open the valve cover? Do I have to take out anything else with it?

 

[happy guy]

Hello Guys, that air leak is the PCV diaphragm showing it's broken (perished). That hole should not be blowing air and is just there to allow atmospheric pressure on the back side of the diaphragm and also as a tell tale hole. The diaphragm separates crankcase pressure and inlet manifold vacuum. Once the diaphragm is damaged crankcase pressure is allowed into the vacuum side and has the effect of forcing engine oil out of the crankcase and thus risking major damage the engine internals.

I suggest Do NOT operate the engine once you hear this leak as major engine damage may follow. I've just replaced this diaphragm and unfortunately the couple of km's that was driven while the PCV was leaking has caused big internal engine damage, so out comes the engine for rebuild. See attached page from the VW manual. SEE NOTE: on page 21 of attachment from VW.

I attach a pic of my PCV diaphragm once removed.

PCV valve replacement by dealer is around $1,800 (Aust)
an alternative is an aftermarket diaphragm change:

Beware aware that the PCV changeout its not a simple task and requires some specific tools.


RKX VW & Audi 3.6 & 3.2 Engine Valve Cover PCV Valve Diaphragm

Good luck.

 

[FrankRizzo]

Hey mate, fellow aussie here and I'm about to travel the journey you've just travelled. I have a 2009 Audi Q7, same engine 3.6l FSI.

Is there any other tips or tricks you think I should probably know about. Like did you actually have to remove the fuel rails? I've read that you have to but seeing where they are placed I'm at a loss to know why they'd need to be removed. Then again I haven't even removed the intake manifold yet. If you did have to remove the fuel rails, how did you go about depressurising it first?

Did you have any problem getting the caps off the coil? (did you use a tool for that)

And finally, where did you get that manual from? It looks fantastic...


Thanks
Frank

 

[happy guy]

Hi Frank, I'm in Perth. Its BIG job. (I'm a mechanic and although I haven't worked in that capacity for a few years now, I do have lots of engine experience and tools). This job was right up there in the difficult stakes. Firstly there are lots of ancillary items to be removed and yes the high pressure fuel pump and fuel rails have to come off as well as lots of other items. My fuel rails were almost seized on and were difficult to remove. If you are going to attempt this I'd highly recommend downloading the workshop manual and following it to the letter. I was quoted around $1,800 for the dealer to replace this PC valve and in hindsight there is a reason why its that expensive. Since then I've had to remove and rebuild that engine in the driveway of my street which was a big job too. But all running smooth as silk now. Parts cost $4,500 but the dealer quoted either $9,700 or $19,700 to do the job depending upon the damage they found once removed. Good luck

 

[FrankRizzo]

Yikes..

Ok well thanks mate.

I am going away for Xmas and need to do this week. It's not throwing an CEL's but the vacuum is very strong, and I can feel suction on the housing of that pcv valve. I'm towing a light camper trailer and I don't want to risk it, I have to give it a go.

I'll take it slow and steady...

 

[happy guy]

Hi Frank, I wouldn't run the engine at all until the diaphragm is replaced. It's got the potential of damaging the engine. The aftermarket diagram I brought from the USA took around 2 weeks to arrive and was well made and did the job well (approx $40). This part is not a dealer item as they sell the entire manifold with diaphragm in place (around $450) I'd allow around 10 -12 hrs to remove it, 3 hrs to replace diaphragm and clean up and another 10-12 hrs to refit.

 

[FrankRizzo]

Thanks yeah I definitely do not want to drive it. Not going far but obviously a car full of kids and towing a van the additional stress might be enough to cause serious damage.

I back myself to get it done. Just got to be patient and take my time.

If you have any further advice regarding this I'd really appreciate it... otherwise...wish me luck.

 

[happy guy]

Wishing you good luck. A quarter dive socket set with set of torx bit sockets will be more than helpful, also a quarter inch drive torque wrench is necessary. The other very useful tool that will save lots of time is the VW water hose clamp removing/installing pliers.

 

[Beka88]

A few pictures might come handy for some