Catch Can Info/Discussion

edk

Addicted to Torque
Staff member
Cleaning my intake/egr valve the other day. Had the catch can pipes disconnected and I saw how the thing was doing dick all. There's oil in the boost pipes, and the amount of oil vapour flowing out of the catch can was like a smoke machine.

So it was either invest in a baffled catch can (£90+), or as James at JD-M suggested vent the crank case in to the exhaust. Opted for the latter, so bought some black hose and a bung for the in take pipe. Result will be cooler intakes, cleaner air, less oil lining boost pipes. I'm willing to risk 'unmetered' air. Thoughts?

-mobile phone post-
 

Sam

Moderator
Staff member
you will need some form of valve before going straight into the exhaust
 
id just put a filt on the rocker mate, :)
and block off the inlet on the intake
simples.

or block off the intake and put a filter on the outlet on your catch tank so it goes into the catch tank then filter out the breather filter
 
id just put a filt on the rocker mate, :)
and block off the inlet on the intake
simples.

or block off the intake and put a filter on the outlet on your catch tank so it goes into the catch tank then filter out the breather filter
there is a very good reason not to put a filter on there.

you HAVE to plumb the crank case ventilation into the intake on our cars as it is a system designed to increase ring seal. when i put a filter on mine it was undrivable. way down on power. which probly means my rings are on borrowed time...

Crankcase Ventilation Explained
 
  • Like
Reactions: edk
ah cheers ross, :)
ill look into getting my turbo one piped bk in,

will pre turbo be ok or after turbo?
i have a inlet just after the maf,
 
When he mentions "Ring Seal" i cant help to say in my head "ring Sting"

Dunno y lol.. Anyone else have this problem lol - Not actual ring sting, but reading it wrong
 
ah cheers ross, :)
ill look into getting my turbo one piped bk in,

will pre turbo be ok or after turbo?
i have a inlet just after the maf,
pre turbo mate,

if you put it post turbo you will be boosting your crankcase.

(sorry ed!)

i dont think plumbing it into the exhaust is a good idea as the exhaust is pressurised, and as per that link above, you need the vac to draw out the crank case gases.
 
Could you not plumb it into the exhaust with a non-return valve? The exhaust gasses should pull the crank case gasses out surely?

*Edit* Ignore that. What about a smog pump like on the old vauxhalls?
 

edk

Addicted to Torque
Staff member
Hrm. Looks like I need to invest in a decent catch can then :/

-mobile phone post-
 

edk

Addicted to Torque
Staff member
there is a very good reason not to put a filter on there.

you HAVE to plumb the crank case ventilation into the intake on our cars as it is a system designed to increase ring seal. when i put a filter on mine it was undrivable. way down on power. which probly means my rings are on borrowed time...

Crankcase Ventilation Explained
From my understanding there it's only important to make sure pressure is released from the crank case. So why wouldnt venting to the exhaust work? Wouldnt the back pressure be enough to pull the gasses out from the case and not have exhaust gases flow back up the vent pipe?

I understand how just venting to atmos isn't enough to expel the crank case pressure, but there must be another way other than using the intake system?



Using the Exhaust to Create Suction (Via a Venturi) to Ventilate the Crankcase on 1991-1999 Engines



Effect on the following characteristics:

De-clutters the engine bay - No
Simplifies crank case ventilation system - No
Helps remove more oil from the air - No
Help evacuate the crank case - Yes
Maintains or improves the stock flow capacity - Yes
Helps promote ring seal and prevent blow-by - Yes
Helps prevent oil smoke in exhaust - Yes
Helps prevent dip stick from popping out - Yes
Helps prevent oil leaks due to pressure - Yes
Helps keep intake track clean including throttle body - Yes
Helps keep intake manifold/plenum clean - Yes
Maintains or reduces amount of pollutants - No
Maintains prevention of un-metered air from entering the intake - Yes
Consensus: GOOD IDEA
 

edk

Addicted to Torque
Staff member
It might also be worth noting that I only have the one vent, on the right side of the rocker cover, and with no PCV valve.
 
I might be completly off the mark here. But are you on about the top right exit on the rocker cover. If so i have an oil breather there (looks like a mini k&n) is that a bad thing ? . If im being a idiot dont be afraid to say ha ha.
 

edk

Addicted to Torque
Staff member
According to the guide there in Ross' link, yes, you're being an idiot :lol:
 

shaggy_master

brapp brapp!
Please not I've always had my breather system properly plumbed in and some of my rivals haven't ;)
I think it is worth doing tbh
 

edk

Addicted to Torque
Staff member
After lots of reading up on it there seems no reason to not have it plumbed in. Trick so as to not reduce performance is if you can properly condense the oil out of the vapours. There certainly seems to be a fair amount in mine.

My pipes going to and from my catch tank were cheap and a pretty small bore so I've put back the OEM breather hose (seeing as the catch tank didn't seem to be doing much). I'm ordered some decent hose, and am looking into buying a baffled larger tank, or doing a tried and tested stainless steel scrubber mod by stuffing the catch can with the stuff so there's way more surface area for the oil to condense on. I'll try the SS Scrubber method in my current can first, if that doesn't work then I'll upgrade.
 
K

Kiwibacon

Guest
Diesels breathe a lot more than petrols, especially turbo diesels. The catch cans that work on a typical petrol are generally woe-ful on an oiler. Venting the crankcase won't do anything bad performance wise, but it'll make a huge mess. I won't do it even on my work car, so there's no way you'd be happy with it on yours.

Get yourself one of these:

They are a real air/oil seperator made to work on man-sized diesels. They can run either return to sump or to a collection can.
 

edk

Addicted to Torque
Staff member
Thanks Kiwi, will definitely look into that. Will have to find out where to buy and how much :).

I've done the tweaks to my current setup for now.


Stainless scourer in.
PTFE tape round all the threads (it leaked like a bitch before).


Scourer seen though the ports.


Beefed up the mounting. This is an ebay special tank and comes with tiny little screws for mounting.


OEM pipe.


New silicone hoses to replace the little rubbish orange ones I had.


Money shot.
 
Top Bottom