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Catch-tank breather system ?

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Old Apr 10, 2007 | 06:32 PM
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Default Catch-tank breather system ?

Another catch-tank thread

After my recent problems with my rear crank seal failing,ive had a close look at my breather system and catch tank that was on the car when I bought it.

Both the rocker cover breathers are tee'd together and the crankcase breather also joins this and then goes off to the catch-tank.

I have noticed today that the PCV valve is still fitted and there is a pipe that goes from here to the throttle body.

Im under the impression that the PCV valve is best removed and a blanking plug fitted to the throttle body ?

Can anyone give me a detailed description of what to remove and which pipes should go where ?
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Old Apr 10, 2007 | 08:32 PM
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Anyone ?
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Old Apr 10, 2007 | 08:40 PM
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Si, if I was you, I would run 2 seperate catch tanks 1 for each side of the breather system.
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Old Apr 10, 2007 | 08:55 PM
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Yeh,but I need to know for sure what to do with the PCV valve,blocking the TB etc ??
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Old Apr 10, 2007 | 08:58 PM
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Well on the evo, I left the PCV in place and took the feed from that to the catch tank and blocked the port on the tb (bolt in the hose).

Didn't cause any problems doing that.

I wouldn't remove the pcv as it's there to stop the fumes going back into the system on the overrun etc.
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Old Apr 10, 2007 | 09:01 PM
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I was told it's not the best idea to T 2 breather lines together.

I'm not 100% sure why it's not a good idea, unless it's to do with the fact that only 1 PCV is fitted so it can force the fumes / oil mist into the side that doesn't have the pcv fitted, or maybe it just blocks up the system under load ? (with 2 sides of an engine / rocker cover trying to breath into 1 line).

Maybe someone can answer that 1 ??
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Old Apr 10, 2007 | 09:02 PM
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Originally Posted by cossie01
Well on the evo, I left the PCV in place and took the feed from that to the catch tank and blocked the port on the tb (bolt in the hose).

Didn't cause any problems doing that.

I wouldn't remove the pcv as it's there to stop the fumes going back into the system on the overrun etc.
Ive had a quick search on here and most people say remove the PCV and blank off the TB. I just want to know exactly how it should be done ?
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Old Apr 10, 2007 | 09:05 PM
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Originally Posted by cossie01
I was told it's not the best idea to T 2 breather lines together.

I'm not 100% sure why it's not a good idea, unless it's to do with the fact that only 1 PCV is fitted so it can force the fumes / oil mist into the side that doesn't have the pcv fitted, or maybe it just blocks up the system under load ? (with 2 sides of an engine / rocker cover trying to breath into 1 line).

Maybe someone can answer that 1 ??
The 2 rocker breathers are joined anyway.

What im thinking of doing is just having some hose going from each of the rocker breathers down under the car with filters on the end and then the same for the crankcase breather. Not going to bother with the catch tank.
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Old Apr 10, 2007 | 09:06 PM
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I don't know what if any difference it makes, but when I asked Si @ Performance Autoworx (the guy that did all the work on my Evo's) if I should remove the PCV he told it not to, as it allows the fumes to be sucked back in on the overrun if it's removed.

Might be different on the scoob, but I wouldn't have thought so.

Leaving it in place won't cause any problems, just block off the tb and run the pcv to catch tank
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Old Apr 10, 2007 | 09:08 PM
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Originally Posted by 340BHP-WRX
The 2 rocker breathers are joined anyway.

What im thinking of doing is just having some hose going from each of the rocker breathers down under the car with filters on the end and then the same for the crankcase breather. Not going to bother with the catch tank.

Yes I know there joined as std on the scooby, but that was meant for a car running 240 / 260 bhp ? your running a fair bit more than that now

The filters are a good idea, but if your car does breath your gonna have oil everywhere underneath, and you will smell all the fumes in the car unless you have the filters near the back of the car.
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Old Apr 10, 2007 | 09:22 PM
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Originally Posted by cossie01
Yes I know there joined as std on the scooby, but that was meant for a car running 240 / 260 bhp ? your running a fair bit more than that now

The filters are a good idea, but if your car does breath your gonna have oil everywhere underneath, and you will smell all the fumes in the car unless you have the filters near the back of the car.
Its not oil that comes out the breathers,that would be bad if it was ! Its condensation and emulsified oil. Searched through some more posts on here and have got a better idea of what to do now.
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Old Apr 10, 2007 | 09:31 PM
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It's fumes and oil mist, the condensation is "enhanced" by the metal catch tank

In reality there isn't that much condensation / water in the system, but the catch tank gets hot and cold pretty quick which creates the condensation.
Either way if you have a breather filter under the car unless it's near the back it will stink.
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Old Apr 10, 2007 | 09:33 PM
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It wont be any different to what I have now. The outlet pipe on the catch tank just goes under the car and at the moment has no filter on the end.
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Old Apr 10, 2007 | 09:35 PM
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The tank is "catching" the mist atm, so most of the smell is staying in the tank.

If you do away with the tank then all the "crap" will get blown out under the car and you will smell it.
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Old Apr 10, 2007 | 09:39 PM
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No,the tank doesnt actually do anything ! As its un-baffled the fumes and stuff just go in it then out through the outlet pipe !! Thats why im just going to get rid of it and have all the breather hoses routed under the car.

Thats how I was shown it at Api.
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Old Apr 10, 2007 | 09:42 PM
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Ok, well in that case, just bin it, it's only there for show
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