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Important: ill effects of catch can plumbing.

63K views 216 replies 62 participants last post by  WidePANDA 
#1 ·
For the past 25k miles i've had no pcv valve, i just put a 90 degree barb in there and then ran a hose from that barb to my catch can with a breather and also the line that goes from the side of the valve cover to the catch can with the breather. You'll find alot of people with it done up like this. It's wrong, and i didn't discover this until just last night.

Think about this for alittle bit....yes, it's ventilating the crank case pressure and it's doing it well enough to make the dip stick pop out and it's doine it well enough to accumulate some oil in the catch can after a few weeks, but the nasty gases remain floating around in the valve cover damaging and breaking down the oil....

This is where an evacuation system is needed. A force is needed to suck everything floating around in the head out of the head and into a sealed catch can. How does the sealed catch can produce a force to suck? From vacuum supplied to your intake pipe before the turbo. Vendors mostly sell them without the barb on them because the idea is to eliminate the oil in your intake system. That's understandable as the stock hose goes directly from the valve cover to the intake, so all we have to do is still something to take out the dirtiness before it get's sucked into the intake. Leave the pcv valve alone and have it hooked up to the IM, because it's doing you good. It's sucking out the fumes into the IM only under vacuum and when the IM shows +pressure then the ball shuts in the valve and the pcv valve closes so your not shooting a bunch of pressurized air into your valve cover. Now the evacuation system is left to the vacuum source from the intake pipe before the turbo, which always has -pressure.

Some of the crankcase pressure could cause blow by on worn rings, it may even cause more heat in the engine leading to perhaps detonation.

:eek: , it's been discussed many times before but i think alot of people don't think about it enough.
 
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#53 ·
White91TalonTsi said:
What if you are not boosting and just are driving to the store to get a temporaty filter for it???!!! For the valve cover though, My line broke off the PVC right now
if there is no line coming from the pvc it will just dirty the throttle body since it right in front of it...i left mines off for like a week ,then realized how much oil it spattered all over the outside of the throttle body...gets a bit messy overtime
 
#56 ·
I have read through this thread and understand the basics and the focus seems to be on the PCV valve. In the case such as mine, I am running the RRE catch can off the crank case (the nipple off the left side of it VC) and haven't touched the PCV valve. My question is, because Greddy has a sealed catch can I can see the problem there, but with RRE's design they have that filter on top of the catch can, with the RRE catch can does this cause any problem discussed in this thread because of the "non sealed" design?
 
#57 ·
10secdreams said:
I have read through this thread and understand the basics and the focus seems to be on the PCV valve. In the case such as mine, I am running the RRE catch can off the crank case (the nipple off the left side of it VC) and haven't touched the PCV valve. My question is, because Greddy has a sealed catch can I can see the problem there, but with RRE's design they have that filter on top of the catch can, with the RRE catch can does this cause any problem discussed in this thread because of the "non sealed" design?
Take the filter off your catchcan and run a line from there to your intake. Besides that you will be fine.
 
#58 ·
10secdreams said:
I have read through this thread and understand the basics and the focus seems to be on the PCV valve. In the case such as mine, I am running the RRE catch can off the crank case (the nipple off the left side of it VC) and haven't touched the PCV valve. My question is, because Greddy has a sealed catch can I can see the problem there, but with RRE's design they have that filter on top of the catch can, with the RRE catch can does this cause any problem discussed in this thread because of the "non sealed" design?
if you have a filter on your catch can on the breather side(not the pcv side), your pcv valve will open under vacuum to evacuate the crankcase pressure and then it will be replaced with unmetered air coming through the filter on your catch can... this, could cause your AFR to run a little lean due to the unmetered air.

additionally, there will be no vacuum under boost to evacuate the crankcase pressure...
 
#60 ·
edmar91 said:
Is The Air Breather Filter Good Or Bad
on what? go back and read through this thread... post #2 addresses MOST of the problems with venting either the breather or the pcv. there is a LOT of information in this thread alone.. just do some reading.

im not trying to be a dick, but this is your first post on this site and any moderator that saw that post would prolly ream your ass about it. i just dont want to see you get booted for some stupid shit, ya know ;)

the search button is your friend on this site!
 
#64 ·
White91TalonTsi said:
hah thats fine, as Long I dont blow up my baby with these vented temorarily..I will NOT be boosting.
Mine didn't blow up for like 3 weeks, it was a really hot day too... Sigh. Sad day, i'm pretty convinced it was because of the vented hoses. Getting on a hot surface and catching some wires on fire or my radiator on fire who knows, it was bad though.
 
#71 ·
Originally Posted by green_bread
Heres a good way to keep boost pressure from your intake manifold from entering your crankcase through a crappy/worn out PCV valve using a check valve and a filter/catch can for an air compressor. Here are the parts you need:

Huskey mini general purpose filter
2 1/4" to 3/8ID hose fittings
US Plastic - 3/8" Kynar® Liquid/Gas Check Valves SKU:64175 ($1.50 a piece from usplastic.com...Will work with vacuum between 2 and 29 in. Hg. and pressures from 1 psi up to 150psi)


Have you tested this valve with a boost leak test? I just noticed that's it's ment for liquid, and they have seperate valves for vacuum. The vacuum check valve specs won't work, so I was wondering if you know for a fact that these valves do?
 
#73 ·
Could running it open and not connected to the intake ( not the intake manifold ) cause your car to knock?
 
#75 ·
forcefead said:
You will run lean at idle and part throttle due to air entering the VC hose with the PCV open so your letting un metered air in. The only time that PCV is shut is when your WOT.
Alright, I will tell my friend so he can get his fixed up.
 
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