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Discussion Starter · #1 ·
So What is an oil catch can?
It is a container or sorts that collects oil from blowback gas vapours an engine produces. I don't think it is very effective and you'll see later.
An Oil/Air separator is better as it is design to extract the oil and soot as well act as a catch can.
With just some easy modifications to the catch can you will hopefully eliminate oil and soot from you intake.
Do I need one?
Dunno... you might, but it depends on how you car is doing Crank Case Venting (CCV) and recirculating the vapours for vehicle emissions.
These vapours are caused in ANY car by the combustion process. Some combustion exhaust gas escapes past the piston rings (blowback gases) and into the internal cavity of the engine where it gets mixed up with your oil.
This caused 2 issues...
1) These blowback gases contaminate your oil with noxious fumes and un-burnt fuel and soot... turning oil black.
2) The reverse also happens... the blowback gases contain oil and soot particles and then are released back into you engines intake via the CCV to be re-cycled as part of the combustion process and then pass out the exhaust through the catalytic convertor. Yes TDi's have special catalytic convertor!
It is problem 2) that creates havoc with my TDi car (and maybe normal petrol turbo engines as well)
Here is my scenario...
I have a Mk3 TDi 66kw engine.
Here is the engine:

The CCV is the disc looking thing ontop of the engine at the right with a hose going to the left and a hose going down the front of the engine.
The hose coming from the CCV to the left across the top of the engine goes straight into the Air Intake.
Hot CCV gases enter the intake's cold air, after the Airfilter and MAF but before the Turbo inlet.
When the Hot CCV Gasses meet the Cold Air condensation occurs and the oil and soot start coating the turbo inlet, the turbo inlet chamber, then all the piping to to the inter-cooler... the inter-cooler then condenses the rest of the Oil and soot from the vapours. The inter-cooler is a very efficient oil air Separator... BUT I don't want it to ba a Catch Can.
So over time Oil collects in your air-air inter-cooler and make it less efficient at what it is supposed to do... and this makes it an oil catch can of sorts and it is a PITA to clean.
What also happens is that the oil and soot that is coating the intake pipe before the turbo also dry out, and a hard sooty coating builds up and starts to block your intake reducing you air flow!
TDi's need air and lots of it to be efficient. So blockages to the turbo intake and oil in the inter-cooler makes for a less efficient engine, and robs you of power and money as you tend to use more fuel to go faster...
this is the catch 22...
as the engine is now less efficient at burning the fuel due to less air and not as good inter-cooler operation, the extra fuel used to go faster makes the problems worse as it is not effectively burnt and this produces more unburnt fuel and soot!!!.
So it makes sense to add one... it will save you problems later. Why car manufacturers don't add one someone will tell me!
Here is the catch can:

Fittings for Inlet and outlet, fluid level sight gauge, and on the bottom a screw plug for draining fluids.
Connecting ip up is pretty simple... You just disconnect the CCV hose to the air intake and add the kit.
The problem is with me and my anal approach to making things work better!
There are issues with nearly ALL Catch cans... the name says it loud and clear... it's a catch can!!!
They are empty containers. Vapours go in and vapours go out, nothing is inside to help stop the vapour problem. (It is best suited for oil spray catchment for those drifters and high G racers. It just catches the oil that comes out of the engine through the CCV.)
Some catch cans contain a baffle or wall to make the vapours take a longer path inside the container... this is better but still not that good.
The Quick and dirty modification to fix this is to just add Stainless Steel wool scouring pads (SS wool).
Yep a simple fix.
Stuff the container full of SS wool. This creates more surface area for the oil and soot to stick to as the vapours enter the container and then tries to leave. Much more effective - and now is an oil air separator!
Now if you look at the design of your catch can you start to wonder how effective is it really!
Well my catch can inlet and outlet pipes are only 2 inch apart... so how effective is it going to be anyway!
There are no baffles inside... so I made one! Baffles are good. If you don't want to spend $$$ on a can with baffles make the baffles!
So what I did was cut my can in 2, and braze a copper angle and pipe around one of the holes... this is now my inlet hole!!!
The design is to force the air to the bottom of the can where it will pass more SS Wool and be extracted.
How I welded Aluminium and Copper:
I bought some of those Aluminium welding rods from the Home Show years ago.
Back then I could not get the rods to work correctly with my primus torch back then... the job was melting before the rods!

So I searched on the net a found a site that had some videos of using a similar rod to weld and repair aluminium.
I came to the conclusion that I did not have a direct enough heat source.... so I went out and bought a portable MAPP torch.
I did a little net surfing on welding dissimilar metals as that is what I'm doing.
I could not find any site of FAQ or Forum that has a method for welding 2 different metals like Copper and Aluminium.
Most of the sites said you just don't do it as there is no need for it in plumbing or tank fabrication. The join would fail under stress from movement or pressure.
Brazing the parts together with plumbers brass rods will not work.
Lead Soldering was an option as the pipe was not under stress or under pressure.
Tig Welding... I don't think so!
Because these Aluminium welding rods can weld non ferrous metals... so I thought copper and Aluminium should be ok.
Here is proof!

Bit untidy... but it worked and it is so strong. the copper pipe was flexing when I tested to see how strong the weld was!
Some closeups...

The Center hole is for the fluid level sight gauge.
The copper pipe comes to about 2cm from the bottom of the can.
I was not going to attempt to Weld the can back together... so I sent it off to get TIG welded...
Because the can is Chromed Aluminium, the chroming process 1st involves plating the can in copper then chroming ontop of the copper.
You cannot TIG weld with copper or chrome layers around the weld so they had to grind back the layers to aluminium.

You would think that the guy who welded it together could have lined up the alignment marks better!!!

So now i wanted to reduce the weld so that it was flush with the can surface.
I especially cut the can here as this is where the mounting ring is positioned.
The Weld:

Filing down the weld... weld is easy... chrome is a biatch to get off!

Hit it with the orbital sander and plain 120 grit paper!
You can see the copper and chrome layers... I thought this was a cool effect and even though of leaving it.

Taking too long with orbital sander... back to filing the whole can surface back to aluminium. Filing was much faster:

Final process... hit it again with orbital sander and 120Grit:

Hit it with orbital sander and Wet and Dry 400 grit then up to 1200 grit:

Thought of polishing it up... can't be bothered.
The top and bottom are still chromed... that's enough blink in the engine bay!
I then filled it up with SS Wool.
It is ready now for mounting... when I pull my finger out and redo my alarm mounting point!
I am pretty happy with the outcome.
Edited: Fixed broken Pics

Modified by Gigitt at 12:44 AM 8-14-2008

3,968 Posts
Discussion Starter · #9 ·
Re: (59Bugto05Golf)

Yeah the best spot to put the catch can is in a cooler spot - Up front etc... but this just becomes messy with tubing running from the back of the engine to the front of the car. I do not think that cooling the can in this way will make a significant difference... This is why you put the SS Wool inside... separation due to surface area contact... not really cindensation.
Most logical spot is on the wheel hump... but In my car these have already got too much bolted too it.. like air conditioner pipes, radiator expansion tank and stuff...
Because I do not have ABS, the brake lines attached to the fire wall has a space above - with good clearance. This is were I want to put the catch can... funny thing is (and what is holding me back) is I have to relocate the car alarm... It was such a good spot to mount the alarm! LOL... so I'm devising a bracket that will accomodate both the alarm and the catch can below it.
Yes I have cleaned out the intercooler before (and all the piping @ ~100,000km) took me about 5 hours total!.
I did not have much oil in the intercooler - only about 20ml... but all the piping and intercooler did have an oily film coating the insides. This all depends on how you drive... but some others have spilled/poured out about 1/2 to 1 liter of oil from the intercooler with similar Km travelled!!! Yep lead foot TDi drivers!!!
To clean them I just used biodegradable Degreaser and water and swished it inside the intercooler about 3 times for about 2-3 minutes each. Then used paper degreaser and towels to clean the pipework.
Most of the time taken was waiting as the intercooler was drying out... took about 3 hours (Also used a hair dryer to make sure it was really dry - you don't want water in there!)
Putting the intercooler and piping back took twice as long than taking it out... aligning the pipework and getting the intercooler back in was tricky.
There is NO issue with this and your catalytic convertor... oil just sits at the most most bottom point - the intercooler! Oil does not go up the intake and then back into the engine... and if it does, by then you should have NO power to even drive the car - because you would not have any cooling capacity and the turbo would be ineffecient etc etc...
You probably do not even have to clean the catch can after adding it (unless you want to clean up the sight level gauge etc or for show... there is a drain screw on the bottom of the can... just drain it!...
Welding was fine... sent it to someone else to do it! cost me $25 for TIG welding.

3,968 Posts
Discussion Starter · #11 ·
Re: (lea)

Quote, originally posted by lea »
so how much are you getting? whats the end verdict, have you looked?

Lea... You Talking to me?
have not installed it yet!
not since I did it 40,000km ago.

3,968 Posts
Discussion Starter · #12 ·
Re: (Gigitt)

Here is Lea's engine...

Lea's has asked if the Mk5 2.0 TDi will suffer the same problem as my Mk3 1.9 TDi engine..
The Green Hilighted area is the Crank Case Vent (CCV) and the red hilighted area is the Breather tube connecting the CCV and the Air Intake just before the Turbo.
My response to Lea:
Just above the Oil Fill cap, you will see the CCV. There is a tube (about 15-20 cm long with a bend) that goes from the left side of the CCV to a big black tube... that is the intake tube...
So Yes you might have the same problem in time.
To test if the problems is starting to occur... you can pull the tube from the CCV to the intake off (looks like you can just slip it off) you can then stick you finger inside and feel/see if you are getting any oil vapours coating the inside.
If you are then you might want to consider an Oil Air Separator.
Better sooner than later.
This should NOT void you warranty. You have not altered in any way how the engine operates... you have really just added a filter. And it is completely legal as all gases getting filtered still pass thought the engine intake. So long as the gases DO NOT vent to atmosphere like some other oil air separators do... this can be illegal and might void your warranty as it could be percieved by VW as altering the way the engine works as you are now NOT recirculating the emissions.
Edited: Fixed broken Pics

Modified by Gigitt at 12:40 AM 8-14-2008

3,968 Posts
Discussion Starter · #15 ·
Re: (Mail2me)

Quote, originally posted by Mail2me »
Is it possible to buy an oil/air separator from any parts supplier? I won't be able to make one

Yes you can... Any performance store will have them.
But they do come in a variety of shapes... and most do not have any internal baffles - this is what My DYI thread is all about.
They will cost you between $100-$500 in store (generic cheapy to Big Name brand llike Greddy etc)
There are also some available that have a breather filter attached... don't get these!
Just search ebay... http://search.ebay.com.au/catc...omZR8
This is where I bouht mine (5R Racing type - there are a few listed on ebay)

3,968 Posts
Discussion Starter · #16 ·
Re: (Gigitt)

OMFG... its about time... I finally finished it and installed it a couple of days ago! LOL
I had to relocate my Alarm Siren and it now sits under the Oil Air Separator.
Here are the install pics...
The Mounting Bracket and rear support bracket:

Mounted with High Tensile bolts and Super Thread lock

The Bracket and mounting bits:



Copper bling! :


My custom siren mounting:

Modified by Gigitt at 12:46 AM 8-14-2008

3,968 Posts
Discussion Starter · #18 ·
Re: (sweatyworker)

Oh yep... only problem is that I have to keep an eye on the Clear Nylon Tubing ... it get hot under there and ATM I do not have any clamps on the 90deg copper angles etc. Don;t want them melting or blowing off... but should be OK and it is not under muc pressure at all.
OK Parts list:
Intake Barb is ~22.5mm OD
CCV Outlet Pipe is 22.5mm OD
Copper 90deg angle reducer joiners (21.5mm OD and 14.5mm OD)
20mm ID Clear Nylon Tubing 30cm (only need 10cm)
12mm ID Clear Nylon Tubing 2m (only need ~1m)
9mm ID Blue Vinyl Tubing came with the Oil Catch Can
6mm Aluminium plate
To mount the can to the firewall I used 6mm Aluminium Plate and same for a backing plate. I Heat Bent the large plate so that the mounting point will be vertical to ground as you are mounting the plate to an inclined firewall.
Plates and Catch Can Mounting brackets were secured with High Tensile M6 Bolts and Nuts with plain Machine washers... No spring Washers used - only Strong Loctite Thread glue. I wanted a clean flush tight pressure join and the spring washers did not spread the load enough. I did not want it shake loose either as the can is really hanging down 10 cm from the main mouting point on the car.
ok... So I used about 5cm 20mm ID Tubing to mate the copper 90deg angles reducers to the Intake pipe and again 5cm for the CCV outlet pipe. Leave the tubing in the sun to softenup... this weeks 38deg days have been good for this
I then connected the 12mm ID to the copper reducers and then pushed the 9mm Blue Tubing inside ~2cm... You just have to improvise... this is the best I could come up with.

3,968 Posts
Discussion Starter · #22 ·
Re: My Oil Catch Can turned Oil Air separtor (ThatGuy)

Quote, originally posted by ThatGuy »
so does this just hang on the supports that you made?

Yeah the can just attaches to the brackets via a large hose clamp.
(I added a small piece of Mouse Mat foam between 'L' braket and Can so as not to damage the alimimum can side when tightening then clamp up.)
There are 2 'L' brackers fixed to the mounting plate.

One of the 'L' brackets has a curved face to fit the side of the catch can.

Okey Dokey... Did a Pela Oil change on Thursday Night... Took some pics of the can and what it is doing.... eeekkkk!
Well it is working:
CCV output tube is covered internally:

A close up of the Tubes... White Paper is behind so as to give a clearer picture and som contrast. I have some oil splattering back out of the Catch Can

A closeup of the inlet/outlet port on the can...

I do not know why the outlet is getting oil splatters from the can.
The Inlet is designed so the vapours are forced too the bottom of the can (via the copper tubeing I added) then all the vapours will then have to pass through all the Stainless Steel Wool before exiting from the top port. The can is not full of oil... but the principle of the can is working... filter the vapours and try and collect/extract the oil.
So why the splattering?
I have to take it off and have a look...
... and while I'm there fix a leak in one of the threads... I need to add some Plumbers Gas or Water tape to all the treads as oil has seeped onto the side of the can from the inlet port.

Modified by Gigitt at 12:42 AM 8-14-2008

3,968 Posts
Discussion Starter · #24 ·
Re: (yeayeayea)

Quote, originally posted by yeayeayea »

What grade ss wool did you use? the real fine stringy stuff should do the trick, not the tangled coil design.

I used the curly SS Scourers... Some course some fine... all ribbon tape... it is not wool. Wool would be too fine and and if any bits break off then they are potential turbo busters... so Scourers was used - plenty of scourers.

I took the Can oof last night to give it some Plumbers tape on the threads... While I had it all unscrewed I just stuffed another 1 big and 3 small SS Scourer pads in there last night after poking a chopstick inside and packing the pad up a bit more. I was trying to get some pads up between the inlet tube and outer wall of the can. This is where there is more chance that the vapours have less pads to pass through ie: letting the gas hit the bottom of the can then straight back up and out. There is like 6 big and 12 small ones stuffed in there now.
Have to temp install it as Im redoing the hoses... and need to drive to get some hoses and clamps.

I decided that I'll put 3cm length of small hose over the inlet/outlet pipes and nipple, then put the 12mm ID clear hose over this as much as I can then use a hose clamp to hold things tight. Will also buy hose clamps for the rest of the system as the nylon hose gets soft with the heat and there is potential for a hose to pop off under vibration... just to be safe!

3,968 Posts
Discussion Starter · #28 ·
Re: My Oil Catch Can turned Oil Air separtor (mujjuman)

Catch can is still going and going and going.
Doing it job fine.
Don't know why there were a few oil spots in the outlet... but thats all there was and still is in the pipe.
The Inlet pipe is black now the outlet still has a light brown stain.
A catch can is not going you remove 100% of the oil out of the CCV air. if you get 95% oil out then that still mean you will not have clean you intercooler for another 100 years!

3,968 Posts
Discussion Starter · #32 ·
Re: My Oil Catch Can turned Oil Air separtor (AA003)

Quote, originally posted by AA003 »
This thread is really out of character with Vortex!
An intelligent post on Vortex ??? One for Mythbusters.
(Gigitt must be Azn)

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