Got Boost: Oil Catch Can and Dealing with the PCV

blueroadster · 07-12-2007, 11:35 AM

Here is a PIC from the shop manual that shows the flow of air through the crankcase.

As you can see from the flow, clean air comes from the intake pipe and goes into the crankcase via the valve cover. The gunk and sludge from the crankcase exits out from the PCV and gets recycled into the intake manifold. To prevent the sludge and gunk from getting int the intake manifold, you should install a sealed and baffled catch can inline along with a check valve. It would go like this:

PCV > hose > sealed and baffled catch can > hose > one way check valve > hose > nipple on the intake manifold

For the nipple on the crankcase, you could either connect a hose from it to the intake pipe (if there is a nipple there) or just install a breather filter.

The above is how I currently have the connections made. There is another point to be made about this setup though...When vacuum is present, the air flow as depicted in the above picture remains the same and the oil catch can collects the gunk so it does not get thrown back into the intake manifold. Things however change when boost is present. In that scenario, the check valve will seal to prevent boost from being blown past the PCV and into the crankcase. With this one side plugged, there is no vacuum present in the crankcase to help escape the gunk. Instead, there would only be one opening (via the breather filter on the nipple of the valve cover) that will not be sealed. When boosting, excess pressure in the crankcase will blow out from this filter and that is the reason why some have noticed that their breather filter on the valve cover gets dirty. What you really want to do is to ensure that there is about 14 inches (or 7psi) of vacuum on the crankcase whether vacuum or boost is present. Here is how I plan to achieve that:

1) Install a breather filter onto the nipple on the valve cover.

2) Remove the PCV hose from the PCV and intake manifold.

3) Install a cap and plug the PCV hose connection on the intake manifold.

4) Remove the PCV entirely.

5) Install a fitting to screw into where the PCV was originally located. The other end of the fitting could be a push-lock, male AN fitting, etc. depending on the type of vacuum hose you wish to run (braided, push-lock, etc.).

6) Run a hose from the new PCV fitting to a sealed and baffled catch can.

7) Run another hose from the sealed and baffled catch can to a female threaded AN fitting.

8) Get some SS hose and install a male threaded AN fitting on one end and attach to the female threaded AN fitting in item 7.

9) Weld in a bung onto the exhaust after the O2 sensors and install a check valve. Here is a PIC of the parts needed:

10) Attach the other end of the SS hose in item 8 to the check valve nipple in item 9.

In the above configuration vacuum will be present regardless of whether the intake manifold sees vacuum or boost. This will allow for the airflow in the first PIC to remain constant. The only issue that would need to be delt with is to ensure that there is enough vacuum present (around 14 inches). If too much vacuum is present, you could drill a hole on the top of the catch can and install a vacuum control (relief) valve to regulate the amount of vacuum on the hose going to the PCV connection. Here is a PIC of a simple vacuum control valve:

blueroadster · 07-12-2007, 12:58 PM

If you do not want to install a catch can and got boost, then you should install a one way check valve on the PCV line.

This will prevent the PCV from seeing positive pressure (thereby also increasing the lifespan of the PCV) where the boost could escape past the valve and into the crankcase or blow right into the crankcase if the PCV has failed. Either case is not good and a one way check valve will provide protection and safety. To test to see if your PCV is functioning correctly, all you need to do is crimp the hose running off of the PCV. If you hear the PCV clicking, then it is fine. If you do not hear clicking when the hose is crimped, then the PCV is not functioning correctly and needs to be replaced.

***NighHawk8Gen*** · 07-12-2007, 02:57 PM

Wow, thats a lot of info. But it is definatley important to consider. I think I'll go with the check valve for now until I work up either the balls or the boredom to perform the elaborate set-up. Or I'll just wait ntil you post the DIY hehe. Kudo's once again!! Sticky?

You must spread some Reputation around before giving it to blueroadster again.

nelsonr31 · 05-13-2008, 05:24 PM

Hey Blue do you still have these pcv line check valves for sale? My greddy kit is on the way and I would like to take all the precautions neccesary.

ItsMeRicky07 · 05-13-2008, 05:33 PM

wow pretty kool about the constant vacuum part. I might upgrade my set up in the future. I just hate welding -.-

blueroadster · 05-13-2008, 06:51 PM

Quote:

Originally Posted by nelsonr31

Hey Blue do you still have these pcv line check valves for sale? My greddy kit is on the way and I would like to take all the precautions neccesary.

No, I do not. You can order them from this link. I forget the exact size, but it was either 3/8" or 1/4". You want to get the one with the Kynar housing.

nelsonr31 · 05-13-2008, 07:57 PM

^ Thanks ^

soxfan143 · 06-10-2008, 09:46 PM

Hey blue, which way do you not want the air flowing if I install the baffled catch can and the check valve on the PCV? Which way should the check valve flow be going on that setup. Should the flow be going into the crankcase? I'm a little confused as to which way the air is not supposed to flow. I know you explained it but I think I'm over thinking this whole thing and confusing myself. lol. Also, would you recommend a catch can from the valve cover to the intake pipe in a boosted situation as well. I really don't want oil blowing through a breather filter or back into the intake piping into the compressor wheel. I have 2 catch cans one is a regular GReddy one and I have a home made one that I'm going to put on the PCV system like you suggested. I just need a little help on this. Thanks Blue.

Oh. And the PCV hose is 3/8" in case anyone was wondering. The 1/4 check valve is too small.

-Mike

ItsMeRicky07 · 06-11-2008, 09:02 AM

a catch can is not needed for the hoses going into the intake. I ran them both to a catch can for over 2k miles and they caught nothing. I think as long as the one on the manifold has a catch can thats all you need. I just removed the ones on my intake last night and put on breathers. My manifold one is catching alot though.

soxfan143 · 06-11-2008, 02:20 PM

So I could actually use the breather bung on the intake tube for my recirculation fitting for my BOV system and just put a breather filter on the valve cover. That makes everything so much easier for me. Where can you find the breather filters. Can I just use a cheap autozone one for now until I can get a good one? I won't have time to wait for it to show up if I order one. The kit will be going on before it could get here. Do you know thw Outside diameter of the breather fitting on the intake tube? I haven't gotten my kit yet I get it tuesday. If you could help me with that I can order the correct size tubing now so I can have it here asap. Thanks.

blueroadster · 06-11-2008, 02:31 PM

I sent you a PM where I tried to answer your questions.

Do not install breather filters; I'd suggest searching on that topic as there was a recent discussion related to them. Keep the stock hoses running from the intake pipe intact. Other than that, I would strongly suggest installing thne turbo kit the way it was intended and getting the car running right before you start modifying other things (like recirculating the BOV).

soxfan143 · 06-11-2008, 03:12 PM

I just read your PM Eric. Thank you so much. I actually sent you a reply. Thanks again bud.

07-12-2007, 11:35 AM	#1 (permalink)
blueroadster Senior Member Member Join Date: Aug 2006 Location: Maryland Posts: 3,573 iTrader: 7 / 100%	Got Boost: Oil Catch Can and Dealing with the PCV Here is a PIC from the shop manual that shows the flow of air through the crankcase. As you can see from the flow, clean air comes from the intake pipe and goes into the crankcase via the valve cover. The gunk and sludge from the crankcase exits out from the PCV and gets recycled into the intake manifold. To prevent the sludge and gunk from getting int the intake manifold, you should install a sealed and baffled catch can inline along with a check valve. It would go like this: PCV > hose > sealed and baffled catch can > hose > one way check valve > hose > nipple on the intake manifold For the nipple on the crankcase, you could either connect a hose from it to the intake pipe (if there is a nipple there) or just install a breather filter. The above is how I currently have the connections made. There is another point to be made about this setup though...When vacuum is present, the air flow as depicted in the above picture remains the same and the oil catch can collects the gunk so it does not get thrown back into the intake manifold. Things however change when boost is present. In that scenario, the check valve will seal to prevent boost from being blown past the PCV and into the crankcase. With this one side plugged, there is no vacuum present in the crankcase to help escape the gunk. Instead, there would only be one opening (via the breather filter on the nipple of the valve cover) that will not be sealed. When boosting, excess pressure in the crankcase will blow out from this filter and that is the reason why some have noticed that their breather filter on the valve cover gets dirty. What you really want to do is to ensure that there is about 14 inches (or 7psi) of vacuum on the crankcase whether vacuum or boost is present. Here is how I plan to achieve that: 1) Install a breather filter onto the nipple on the valve cover. 2) Remove the PCV hose from the PCV and intake manifold. 3) Install a cap and plug the PCV hose connection on the intake manifold. 4) Remove the PCV entirely. 5) Install a fitting to screw into where the PCV was originally located. The other end of the fitting could be a push-lock, male AN fitting, etc. depending on the type of vacuum hose you wish to run (braided, push-lock, etc.). 6) Run a hose from the new PCV fitting to a sealed and baffled catch can. 7) Run another hose from the sealed and baffled catch can to a female threaded AN fitting. 8) Get some SS hose and install a male threaded AN fitting on one end and attach to the female threaded AN fitting in item 7. 9) Weld in a bung onto the exhaust after the O2 sensors and install a check valve. Here is a PIC of the parts needed: 10) Attach the other end of the SS hose in item 8 to the check valve nipple in item 9. In the above configuration vacuum will be present regardless of whether the intake manifold sees vacuum or boost. This will allow for the airflow in the first PIC to remain constant. The only issue that would need to be delt with is to ensure that there is enough vacuum present (around 14 inches). If too much vacuum is present, you could drill a hole on the top of the catch can and install a vacuum control (relief) valve to regulate the amount of vacuum on the hose going to the PCV connection. Here is a PIC of a simple vacuum control valve: Last edited by blueroadster; 07-12-2007 at 03:10 PM.

07-12-2007, 12:58 PM	#2 (permalink)
blueroadster Senior Member Member Join Date: Aug 2006 Location: Maryland Posts: 3,573 iTrader: 7 / 100%	If you do not want to install a catch can and got boost, then you should install a one way check valve on the PCV line. This will prevent the PCV from seeing positive pressure (thereby also increasing the lifespan of the PCV) where the boost could escape past the valve and into the crankcase or blow right into the crankcase if the PCV has failed. Either case is not good and a one way check valve will provide protection and safety. To test to see if your PCV is functioning correctly, all you need to do is crimp the hose running off of the PCV. If you hear the PCV clicking, then it is fine. If you do not hear clicking when the hose is crimped, then the PCV is not functioning correctly and needs to be replaced. Last edited by blueroadster; 07-12-2007 at 03:13 PM.

07-12-2007, 02:57 PM	#3 (permalink)
*NighHawk8Gen* They like my swag.... Join Date: Mar 2006 Location: Germany Age: 28 Posts: 376 iTrader: 0 / 0%	Wow, thats a lot of info. But it is definatley important to consider. I think I'll go with the check valve for now until I work up either the balls or the boredom to perform the elaborate set-up. Or I'll just wait ntil you post the DIY hehe. Kudo's once again!! Sticky? You must spread some Reputation around before giving it to blueroadster again. __________________ New Project: 2008 BMW 135i :)

06-11-2008, 02:20 PM	#10 (permalink)
soxfan143 Senior Member Join Date: Nov 2007 Location: Lynnfield, MA Age: 34 Posts: 3,226 Mike iTrader: 4 / 100%	So I could actually use the breather bung on the intake tube for my recirculation fitting for my BOV system and just put a breather filter on the valve cover. That makes everything so much easier for me. Where can you find the breather filters. Can I just use a cheap autozone one for now until I can get a good one? I won't have time to wait for it to show up if I order one. The kit will be going on before it could get here. Do you know thw Outside diameter of the breather fitting on the intake tube? I haven't gotten my kit yet I get it tuesday. If you could help me with that I can order the correct size tubing now so I can have it here asap. Thanks. Last edited by soxfan143; 06-11-2008 at 02:22 PM.

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05-13-2008, 05:24 PM	#4 (permalink)
nelsonr31 Senior Member Join Date: Sep 2007 Location: nunya Age: 27 Posts: 1,876 iTrader: 23 / 100%	Hey Blue do you still have these pcv line check valves for sale? My greddy kit is on the way and I would like to take all the precautions neccesary.

05-13-2008, 05:33 PM	#5 (permalink)
ItsMeRicky07 Senior Member Join Date: Dec 2007 Location: Port Saint Lucie, FL Posts: 377 Ricky iTrader: 7 / 100%	wow pretty kool about the constant vacuum part. I might upgrade my set up in the future. I just hate welding -.-

05-13-2008, 07:57 PM	#7 (permalink)
nelsonr31 Senior Member Join Date: Sep 2007 Location: nunya Age: 27 Posts: 1,876 iTrader: 23 / 100%	^ Thanks ^

06-10-2008, 09:46 PM	#8 (permalink)
soxfan143 Senior Member Join Date: Nov 2007 Location: Lynnfield, MA Age: 34 Posts: 3,226 Mike iTrader: 4 / 100%	Hey blue, which way do you not want the air flowing if I install the baffled catch can and the check valve on the PCV? Which way should the check valve flow be going on that setup. Should the flow be going into the crankcase? I'm a little confused as to which way the air is not supposed to flow. I know you explained it but I think I'm over thinking this whole thing and confusing myself. lol. Also, would you recommend a catch can from the valve cover to the intake pipe in a boosted situation as well. I really don't want oil blowing through a breather filter or back into the intake piping into the compressor wheel. I have 2 catch cans one is a regular GReddy one and I have a home made one that I'm going to put on the PCV system like you suggested. I just need a little help on this. Thanks Blue. Oh. And the PCV hose is 3/8" in case anyone was wondering. The 1/4 check valve is too small. -Mike

06-11-2008, 09:02 AM	#9 (permalink)
ItsMeRicky07 Senior Member Join Date: Dec 2007 Location: Port Saint Lucie, FL Posts: 377 Ricky iTrader: 7 / 100%	a catch can is not needed for the hoses going into the intake. I ran them both to a catch can for over 2k miles and they caught nothing. I think as long as the one on the manifold has a catch can thats all you need. I just removed the ones on my intake last night and put on breathers. My manifold one is catching alot though.

06-11-2008, 02:31 PM	#11 (permalink)
blueroadster Senior Member Member Join Date: Aug 2006 Location: Maryland Posts: 3,573 iTrader: 7 / 100%	I sent you a PM where I tried to answer your questions. Do not install breather filters; I'd suggest searching on that topic as there was a recent discussion related to them. Keep the stock hoses running from the intake pipe intact. Other than that, I would strongly suggest installing thne turbo kit the way it was intended and getting the car running right before you start modifying other things (like recirculating the BOV).

06-11-2008, 03:12 PM	#12 (permalink)
soxfan143 Senior Member Join Date: Nov 2007 Location: Lynnfield, MA Age: 34 Posts: 3,226 Mike iTrader: 4 / 100%	I just read your PM Eric. Thank you so much. I actually sent you a reply. Thanks again bud.