View Full Version : BSH PCV Replacement & Strage new sounds from Breather Hose

05-23-2013, 05:00 PM

This is my first post here, so I hope I’m following the rules properly - If I have skipped something, my sincerest apologies.

I’ve recently started exclusively working on my own 2007 A4 B7 in regards to all mechanical needs (within reason and tool allowance, logically). I had for over a year, albeit passively been trying to identify the cause of the excessive 400 mile/liter oil consumption issue. Recently, after more vigorous education on the TFSI 2.0 engine, I had found the common issues associated with this design - notably the poor PCV valve quality. Long story short, I tried to clean the PCV with carb cleaner and after reinstall I noticed physical oil seepage from a still unknown source, which was not the case before at all! I assumed it had to be the PCV had fully been screwed up at this point and a replacement was due.

I picked the BSH modification instead of OEM for multiple reasons; Reasons obvious to anybody even remotely familiar with B7 A4 issues. After BSH replacement, I noticed a nice power increase and more "relaxed" engine dynamics, where before the engine felt uncomfortable with itself (like a plugged up nose in a human) and peaky, both under load and idle. (The previous statement is purely subjective and is used for illustrative purposes in regards to who so ever may understand).

However, after the BSH replacement, I noticed a rattling sound from under the hood. It sounded, honestly, like my intake filter was bumping against the car chassis corresponding to the engines vibrating frequency. After further inspection, I found that was not the case, at all and although the noise was coming from within the filter, the cause was not the filter itself. After removing the filter, I visually saw where the sound was coming from immediately. The breather hose, which is connected to the turbo inlet, had small amounts of smoke puffs at each engine rotation cycle. Now this is small amounts of smoke, and I would even consider it normal had it not been for the noise. It’s a puffing noise that literally sounds like you have something loose vibrating against the chassis of the car.

Question 1:
Isn’t the breather hose supposed to be INPUTTING air into the crank case, not puffing it out? Or am I misunderstanding the purpose of this hose? To me it looks, clearly as outputting crank pressure with some smoke and oil as well. I was under the impression that’s what the heck the PCV was supposed to do...

Is this normal with the new BSH PCV? I’m leaning towards a logical, no.

I’ve placed a video on YouTube illustrating what I mean. You will see the smoke puffs I’m referring to and hear the noises, as well.


Note: Before PCV replacement, quite a bit of oil was leaking into the turbo housing from this breather hose, in fact my intercoolers are still oiled as are all the tubes and part of the throttle body. I’ll need to drain those again, and clean the oil out of the intercoolers, right?

Question 2: Is it normal for oil to be seeping through the breather hose into the turbo inlet, and subsequently through the entire air intake system? I drained over half a liter of oil from intercooler piping itself, and my air filter is thoroughly oiled. This was, of course before the PCV replacement. Should I bother with draining the oil from the intercooler piping again, or is it just "how it be"?[:)]

Question 3: Would a broken PCV valve, left unattended to for several months cause permanent damage to an engine? For instance, I had suspected issues with the PCV for a while, before I knew about what it does. And oil was being burned NOT leaked out. The engine never had a drop of oil leakage before I attempted to clean the OEM PCV valve, just burning oil and the occasional exhaust puff at 5k RPM every now and again. Would my ignorance could have caused damage to the engine, or worn out components such as gaskets and seals anywhere, permanently? Where would be the most cause for concern, if so?

Question 4: What is the likelihood that the BSH PCV replacement valve will stop the engine oil leakage from the unknown location, which occurred after OEM PCV cleaning attempt?

Question 4 Note: Its almost impossible to see where the oil is coming from because its almost as if it is being sprayed and then leaks throughout the underside of the car. There isn’t any one, visible area where its coming from. The leak is on the passenger side and as far as I can tell is not coming from the turbo itself. Although the turbo housing could be burning the oil up and not leaving a trace to know for sure – though there is no smoking in the engine bay at all.

Any help and answers to these questions are welcomed. Thank you!

05-29-2013, 02:33 PM
Well, I think that when you removed the PCV system that pressue has to go somewhere and it's going through the turbo inlet. I'm surprised that you can hear it with everything connected though. The only thing the Oil going through the PCV system unchecked will do is create dirty intake ports and clogged valves that everyone is always complaining about. You can find numerous posts related to that.

You can't really stop the oil completely unless you undo all the breather hoses to any of the intake paths. After all, there is oil underneath that valve cover and those breather hoses all come from that area. There are more complete answers that basically give you the technical reasons associated with running a turbo powered direct injection car that has no injectors in it's intake manifold, but you'll have to search them out. But basically it's the way this engine was designed to some degree.

Still, I'm curious how loud that noise is from the driver's seat. I'm considering a similar mod that gets rid of the PCV valve. It's a different billet valve cover that eliminates those ports completely.