Install a catch can on a ecotec V6

[immortality]

How-to install an oil catch can on an ecotec V6 (+ ramblings)

I’ve seen this question asked a time or two, since it’s something I’ve been meaning to do for some time (and suffering from modification withdrawals) I though it’s about time I start this little project.

The Problem:

The standard PVC system on a factory engine is designed to ensure that any crankcase gasses are recycled through the combustion process so as to reduce pollution as much as possible. The standard system does this very well however the standard PCV system has a couple of design flaws primarily being that it introduces oil into the intake manifold/combustion process (in the pic you can clearly see excessive amount of oil around the intake runners for the number 5&6 cylinders).

Let’s have a quick look at the standard PVC system on an ecotec engine, The PCV system starts with a 10mm diameter hose that is connected between the bottom of the throttle body and the LIM (lower intake manifold) where the fitting allows clean air from before the throttle body into the engine crankcase. The air is then sucked into the inlet manifold through the PCV valve taking any crankcase gasses (mainly combustion gasses that have leaked past the piston rings as well as any oil vapour) with it so that it is then processed through the combustion cycle again.

This all well and good on a brand new engine, however by the time the engine has done 100,000km’s + the net result is a large build-up of oil scum inside the throttle body and intake manifold. If you spend enough time on any Holden commodore forum you will see multiple threads about idle issues which can mostly be solved by cleaning out the throttle body, especially the passages for the IAC (idle air control) stepper motor.

The Solution:
Modify the factory PCV system so that the oil vapour is removed from the air by installing a catch can (sounds simple enough) however with any MAF based engine management system you cannot introduce any air into the intake system other than what is measured by the MAF sensor.

There are a few options for modifying the PCV system and fitting a catch can, however I’m trying to set up a system where the basic principle of the PCV system isn’t compromised (i.e. it’s not causing any extra pollution by venting crankcase gasses directly into the atmosphere and therefor being EPA friendly).

The first major problem with modifying the PCV system on an ecotec engine is the fact that the actual PCV valve is fitted internally between the upper and lower intake manifolds. This severely limits the options you have to achieve the goal of removing the oil vapour from the crankcase gasses without making modifications to the intake manifold.

With that in mind I have chosen to fit the catch can in between the TB and LIM and then block the PCV valve between the upper and lower halves of the intake manifold. This will result (I think) in a small vacuum been created in the crankcase (because there is now no clean air source going into the crankcase). I’ve thought about this a bit and I don’t see this as been a problem, If you have a look at a lot of race car engines you will note that they run these engines with the crankcase under a very high vacuum (because it reduces/eliminates windage inside the crankcase reducing parasitic losses inside the engine), to test this theory I will endeavour to test to see if indeed I do achieve a vacuum in the crankcase (although I’m not expecting to see any performance increase from it).

Fitting the actual catch can (the bit you’ve all been waiting to see):
Required parts:
1. Catch can
2. Hose (approx. 1m of 3/8” or 10mm)
3. Basic hand tools and battery drill.
4. A cold brew

I choose to use a catch can from Supercheap because it was on special and it had 2x 10mm hose fittings which are the same size as the fittings on the intake manifold/TB. I also used 3/8” fuel hose because it’s black ( I don’t like the look of the clear hose supplied with the catch can and it wasn’t long enough any way) and I’m going for the stealth look

Optional extras, if you want to ensure maximum oil vapour removal like I do you can fit some steel wool inside the catch can before the air outlet.
To achieve this I have removed the top of the catch can and using some 2 pot epoxy, glued a small steel tube inside one of the hose tail fittings, I’ve then fitted some steelo pad inside the top of the catch can so that any air been sucked out will have to go through the steelo pad. I’ve then re-assembled the catch can ready for installation on the car. (see pics below)



I’ve chosen to mount my catch can directly to my MACE cold air intake as it seems to be the easiest and most convenient place for me (if you choose to do this you will need to remove the intake filter to fit the screws holding the catch can on).


1.Measure and drill the holes to mount the catch can (in my installation I haven’t needed to use the bracket supplied with the catch can).

2.Remove the intake pipe from the TB so that you can remove the factory hose from between the TB and LIM.

3.It's time to fit the new hoses. I’ve fitted my new 3/8” hose making sure to fit the hose coming from the LIM to the hose tail on the catch can which has the extra pipe glued inside. Connect the 2nd hose from the catch can to the bottom of the TB.



I’ve then used a couple of cable ties to tidy up the install and re-fitted the intake pipe to the throttle body. Hopefully you will end up with something that looks like this:


Make sure all you fittings are tight, start the car and check for any vacuum leaks.


The catch can is now fully installed, now all that is left to do is to block the PCV valve inside the intake manifold (I have a few ideas and once I have completed it I will complete this how-to.

Update: PCV valve has been blocked. In this case I have simply removed the valve and squished it flat and then bent it over and re-inserted it in it's original position. Ideally I would have preferred to tap the PCV hole in the upper manifold and then used a grub screw and some thread sealant to seal the hole without having to actually permanently stuff the PCV valve.



Interestingly, under the PCV valve I found a black plastic restrictor. From this one can only assume that the original PCV system was too efficient and was letting to much oil into the upper intake manifold. The black restrictor blocks off a 20mm hole and leaves 2 small holes of approx 3mm diameter for the PCV to breather through.



I've done a few other minor chores while I had it apart, I cleaned our the TB, especially the IAC stepper motor passages, cleaned the MAF and cleaned up a leaking rocker cover gasket.

From first observations, the idle is smoother and throttle response has come back (cleaning the MAF). Now it's a wait and see how things go.

Cheers

disclaimer: I've made every effort to make this as simple as possible, However I take no responsibility for any injury to your person (or others), damage to your vehicle or the accuracy of any information given here in especially with regard to EPA and ADR regulations or anything else for that matter.

[immortality]

I haven't blocked the PCV yet, however there is some weird stuff going on. Fuel economy seems to have improved....... no idea why at this stage. Going to leave it like this for a little while longer to see what happens as it is now.

to Block the PCV I'm going to remove the plenum and simply squish the end of the PCV valve so no air can get through. I was going to do it yesterday however I couldn't find any Silastic at home I had intended to tap the hole in the manifold so that i could simple screw a grub screw into it with some sealant however I don't have a tap big enough at home

cheers

[Dr HaxZaw]

yeah i've got a catch sitting at home waiting to be installed but just need to make a bracket up (not sure whether this justifies buying a welder lol)

The only part im not too sure about is the PCV thing so it will be great when you get some pics up of it

[immortality]

Sounds like a good excuse to me. When I do finally finish mine I will put up some pics

[BowTie]

Cool thread.


Have been thinking about this one for a while as well.

It's a tricky one due to the dual ventilation. The drivers side head gets it's vacuum from the intake runners and uses a pcv, where as the passenger side head gets its vacuum from the airbox side of the throttlebody.

A vy intake that i have shows no signs of oiling through the pcv but has built up huge amounts of crap from the tb/passenger side head. This makes me think a catch can between the intake and tb vent hose would solve most gunk issues.

I have now come the conclusion that you can run both vents into a single can with dual outlets with one feeding back to the intake and the other feeding the tb. The trick is to use one way check valves on both can outlets to prevent airflow bypassing the tb via the can. This way means one can can drain both vents and automatically take its vacuum from the stronger source like it should without affecting measured airflow.

Still, thats awkward, when its much simpler to give either head its own pcv and can and run them independantly.

A dual can setup seems to be the go, I reckon.

[immortality]

OK,

I happen to have a couple more pics of the ports in the heads where the manifold PCV breathers sit on the manifold. From the pics you can see that both
PCV ports on the manifold actually breathe from the engine valley (through a port on the head intake side next to a push rod). This is actually better then the PCV breathing from the heads as it aids oil drain back (major problem with high revving Holden 304/308's which breathe from the heads and tend to hold lots of oil there)

A vy intake that i have shows no signs of oiling through the pcv but has built up huge amounts of crap from the tb/passenger side head. This makes me think a catch can between the intake and tb vent hose would solve most gunk issues.

As you have noted, one of the failings of the factory PCV system is that sometimes there is a greater vacuum in front of the TB then there is inside the manifold, when this occurs oil is drawn back through the breather pipe (instead of the PCV valve) under the TB and you get that horrible gunk buildup inside the manifold and TB.

As some of you will be aware, on the original or early ecotec engines (VS/VT models) the PCV breather hole inside the plenum was located by the number 5&6 intake runners. For the later models (VX/VY) the PCV breather inside the manifold was moved to be just after the TB neck on the plenum directly after the TB. From what i've read the earlier design lead to problems because any oil that did come into the intake manifold founds it's way primarily into the intake runners for the number 5&6 runners contaminating those cylinders and possibly causing a misfire.

I happen to have a late model ecotec intake manifold sitting in the garage and from what I can see the contamination patterns inside the manifold is quiet different between the 2 different PCV layouts. from this I can only assume that the pressure dynamics across the 2 PCV ports has changed by moving the PCV port inside the manifold.

A dual can setup seems to be the go, I reckon.

I agree, to set up a proper catch can system on a ecotec and maintain full proper function of the PCV system will require a dual catch can setup. One catch can as I have setup in my first post and a 2nd catch can on the other side of the intake manifold with a external PCV valve fitted (will also have to block the internal PCV valve). Unfortunately this become quiet involved and a lot more expensive

If you were doing this on a race car where EPA/ADR compliance wasn't a issue you could simply fit a catch can from the breather point(s) on the LIM and then have it go directly to a catch can fitted with a mini filter (breathe to atmosphere) and block both the internal PCV valve and the breather port under the TB. A variation of this which may still meet EPA/ADR compliance is to do as suggested but instead of having a mini filter you could fit a larger breather hose that goes back to the intake filter enclosure this would also work well on a blown engine

[MR_VX]

For the later models (VX/VY) the PCV breather inside the manifold was moved to be just after the TB neck on the plenum directly after the TB.

on my vx s2 the port behind the throttle body is for the EGR hose the connects to the passenger side exhaust header....!

[immortality]

on my vx s2 the port behind the throttle body is for the ERG hose the connects to the passenger side exhaust header....!

correct, the later model ecotec's have the EGR port on the side of the throttle body neck. I had forgotten about this. This probably does explain why the oil residue on the later style manifolds has that "burnt on" look

Pic attached of later model plenum, EGR port can be seen just after where the TB mounts on the side, the PCV hole can be seen on the floor of the plenum directly after the TB neck. On this manifold that area is rather clean possibly suggesting that the oil that is coming though the PCV port is keeping this area clean leading into the number 3&4 intake runners......

Personally, i'd rather that no oil was present inside the intake manifold

[Dr HaxZaw]

So would there be any harm in installing a catch-can between the throttlebody hose and the passengers side of the engine and then blocking off the PCV?? or would the drivers side of the engine suffer then?

[immortality]

Na, not that I can see because the although the fitting may be on "one side" of the intake manifold, it's drawing air from the valley area underneath the intake manifold so in reality it's not biased to one side of the engine.

The way I see it is that you are trying to remove the excess air inside the crankcase, this is being produced primarily as "blow by" from the combustion process into the crankcase area and I guess the sooner you can remove those gasses the better. If you can suck them out at the intake valley it has to be better then doing it at the rocker cover

[VNenvy]

could you drill and tap into the pcv port just under the plenum ant put a 90deg fitting in there and run a hose of that into a catch and then just get the hole for the pcv on the plenum welded up

[immortality]

Hey Mate,

Yes you could, I would recommend removing LIM to do so however so that you don't get any swarf into the engine.

A lot of work.

For a high revving motor it's probably a good idea to have multiple breather lines.

cheers

[MR_VX]

how far have you gone with this other then just installing the can? any progress?

[immortality]

Hey mate,

I have blocked the PCV valve, to soon to tell if there are any changes though. I'll post some pics later in the first post.

Last couple of weeks have been good though, the trip computer average for about the last 6 months is 11litres/100km's however the last 2 weeks the average has been a lot better then that. last week I worked it out at about 9.3 litres/100km's with a few decent motorway trip included.

Cheers


Having said all that, possibly considering upgrading to a 2002 S model with L67

[immortality]

I've updated the first post with pics of the PCV valve arrangement and modified PCV valve. I've also got a pic of a restrictor that is found under the PCV valve......

cheers

[Wombles]

Subscribing to an awesome thread.

[Fenix_Longbow]

Does anyone have any info on doing something like this to the buick engines? Easier or harder? Is it worth it?

[immortality]

It is definitely worth it in my book.

It can be done. The PVC valve is a little easier to get to. There are some slight variations depending on which model 3800V6 engine you have. Also, because the 3800V6 engine is tuned using a MAP sensor you can introduce air into the engine at or before the manifold without it upsetting the tune.

To fit a catch can on the 3800 V6 engine you can simply block the PCV and fit a catch can on the line that goes from the manifold to the underside of the TB and then fit one of those mini filters on the rocker cover to vent the engine. Check my ride for pics of a catch can that i've installed on my VN V6.

Cheers

[Wombles]

So.. Any developments on how it went with the PVC valve blocked?

[immortality]

Well it's not running any worse

But seriously, it's always has a slight miss at idle, never been able to get rid of it totally but it does seem to be gone. I guess it's wait and see over a longer period to see it it comes back.

I'll pull the plenum cover off in a few months and all going well it should still be clean in there

Generally speaking the car is running better now that any time since we've owned it.

I've also got a set of 20% underdriven pulleys going on it tomorrow hopefully

[Clutchy]

Easiest way to block the pcv off is pull the spring off the valve throw the valve over ya shoulder put a 10 cent coin in the hole put the spring back in the hole ontop of the coin does the trick just nice. then ya just run the hose to ya can like ya have from the center of the manifold.

[immortality]

I assume you are referring to the later style 3800 V6 engines that have the internal PCV valve under the large nut at the front of the manifold. The earlier V6 engines have a external PCV valve, I've actually left the PCV valve in place inline with the catch can as it was the easiest way to connect the hose into the manifold and run a external breather on the rocker cover (on top of the oil filler cap).

Seems to work well on the Buick engine. I get a little oil in the catch can but not anywhere enough to worry about it.

[vscom88]

I have a stock PCV system, no oil catch can and my Ecotec is pretty heavily modified .. I've never had any issues with the plenum filling up with oil its generally nice and clean, maybe a fraction of dirt but nothing you would really worry about.

When i pulled my manifold off last the whole valley and balance shaft was all shiney.

Do you rekon i should give this catch can thingi a shot ?

[Gabster118]

I'm considering doing this tomorrow to my VX, Just makin sure, so your saying its better if I thread and put a bolt in the upper PCV hole?
The newer ecotecs have this hole just inside the TB and the air runs down a valley between the plenum and Manifold intake.

[Jonah 101]

Well it's not running any worse

But seriously, it's always has a slight miss at idle, never been able to get rid of it totally but it does seem to be gone. I guess it's wait and see over a longer period to see it it comes back.

I'll pull the plenum cover off in a few months and all going well it should still be clean in there

Generally speaking the car is running better now that any time since we've owned it.

I've also got a set of 20% underdriven pulleys going on it tomorrow hopefully

So hows it going? the PCV mod?