Sucking/gurgling noise from intake

[momento1]

Hi guys,

Lately I have been hearing a loud noise which as first I thought was a knocking noise but since pulling apart the intake side I have located the noise coming from the return line from the crank ventilation. (Excuse my terminology)
It is sounding like sucking or gurgling coming from the return line and when I cover it with my hand(with the engine running) the noise stops.

The car is fitted with a closed loop oil catch tank. But since I have only owned this car for just over a week I don't know how the original Pcv system was setup to understand if the catch tank is setup correctly.
When I picked up the car it wasn't making this noise.

I'm not sure if its related but I'm also seeing inconsistent boost.
When I punch it in 2nd it can see up to 21psi, and sometimes in 3rd I see 25psi (overboost obviously). But other times in 3rd or 4th it won't reach past 16-18psi.
Both issues are annoying me at the moment

I searched through the forum for pcv and catch can but nothing is helping my cause.

[prj]

Post up some pictures of the system.

[bluequattro]

Disappointed, thought this was a rude joke thread by the title!

[sam80quattro]

when i had my car laid up for a few month it did the noise your describing from an engine breather pipe and after alot of reading and worrying i decided to believe it was a sticky piston ring which actually fixed itself after using it again for a few hours...

[sam80quattro]

that was on a 1.8t though..

[UrS4boy]

AAN, ABY, ADU and 3B PCV system info

Hi guys, Lately I have been hearing a loud noise which as first I thought was a knocking noise but since pulling apart the intake side I have located the noise coming from the return line from the crank ventilation. .... But since I have only owned this car for just over a week I don't know how the original Pcv system was setup to understand if the catch tank is setup correctly....
I searched through the forum for pcv and catch can but nothing is helping my cause.

You should have found something here. However, as the quickest response, read this:

AAN, ABY, ADU and 3B PCV system info

[momento1]

prj - i will take some pics tonight and post for you to see.

bluequattro - sorry to disappoint...

urs4boy - thanks for the link. I will try to use that info to see how the catch tank is mounted in reference to the standard setup.

Im hoping that the PCV valve (or N80) is just shot and need replacing

[UrS4boy]

urs4boy - thanks for the link. I will try to use that info to see how the catch tank is mounted in reference to the standard setup.

When asked, this is what I would recommend for a catch can installation location, i.e. after the PCV stuff and before the hose goes into the cam cover on its way to the front of the engine. I believe that it is best (environmentally) to plumb the catch can as part of the PCV system, i.e. no open discharge, just a means to remove most of the oil from the vapour before it gets to the intake system.

[momento1]

urs4boy that is a good diagram in explaining what should occur. However looking quickly last night (as i didnt have much time) i cannot see either PCV or non return valve within the catch tank setup i have. Im starting to think that could be part of my problem.

See pics below:








also noticed the above pic shows a slight kink in the "feeder" line going to the side of the catch tank. That i will need to change with a 90 degree bend hose, but i dont believe its directly related.

I cannot see that well past the cruise control module, however i still dont notice a PCV anywhere, or the one way ball valve (non return valve).

i need to get me hands on a pair of those valves and fit them as per urs4boys pic which is exactly how i had the setup on my S4 catch tank.

P.S. dont mind the little bit of coolant splatter, i had a very small drip from the radiator top hose was dripped onto the fan and splattered everywhere. Makes the engine bay look dirty....

[momento1]

Bump!

Looking into it more last night, i removed the intake pipe and ISV etc etc toget a better look back there and noticed that i do have the "non-return" valve but it doesnt look like a stock item... it looks like its made out of metal... possibly the 034 billet type valve they sell... im not even sure if its mounted correctly as it has "engine" written on it and a little arrow pointing away from the engine. So should it mean that the arrow points to the engine, or does the arrow mean the direction of flow from the engine.
Has anyone installed one of these before or had success with them?
There are some mixed reviews on the forum here about premature sticking on the ball valve and failing, so it has my suspicions aroused

now i can confirm that i do not have a pressure regulating valve (pancake valve) in line with the system before the catch can. My question is, for a correctly flowing system, should i have one installed prior to the catch tank like urs4boys diagram above??

also i discovered the vac line was disconnected from the cruise control pot and just flapping around. i removed the entire cruise control pot and plugged the vac line... i hope that resolved something haha

[UrS4boy]

I seriously don't understand how some people (in this case one of your car's previous owners) think they are smarter than the engineers who designed their engine's positive crankcase ventilation system and just start willie-nillie eliminating portions of the system (probably because the part failed and they couldn't be bothered buying and installing a new part). In this case, I would say buy and install the pancake pressure control/regulating valve in its proper location. I would also say that the catch can should be after the pressure control valve in order to catch the vapours from both the crankcase and from under the cam cover (one cam cover connection is actually ventilation, the other is just a pass-through to the turbo inlet).

The diagram below might help with the above and the orientation of the bleeder valve (Item 20 below). The orientation must be such that under boost, the ball is pushed into its seat to seal off boost from the PCV system. The ball should rattle when the valve is shaken in your hand. Cleaning in solvent might help.

[prj]

I would not recommend fitting the 034 valve, I have first hand experience of a brand new valve from them fitted, then failing, sticking open and boost running into the crank case and the engine suffering bearing failure.

I still don't see a single pic. All your links point to 1x1 pixel images.

[momento1]

Thanks again guys! your worth your weight in gold!

just as i thought, so lucky i ordered a new pancake valve a couple days ago, and a new OEM bleeder valve just in case.

Any thoughts on the disconnected vacuum line from the cruise control affecting performance? i cant see it as a good thing, so i have plugged it anyways.


Im hoping that i get my lost power back once i sort out the pcv system!

[prj]

The pancake is not a valve, it's the so called flame trap, if you mean the black one.

You don't need the OEM valve, you can just blank that portion off and only run it to the MAF-Turbo hose...

As I said, I don't see any pics of your setup so hard to tell what you're working with.
Of course if in doubt, just put it to factory, and it will work for sure.

[momento1]

I still don't see a single pic. All your links point to 1x1 pixel images.

thats odd! im linking to photos that i have uploaded in my album. all pics are in my public album if you care to take a look