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Bumping this.

I grabbed a catch can from Amazon. The engine bay on Gen 2 Volt is tight. Right now I'm looking at the space behind the passenger side headlight for the can install. I want to make sure the can will fit without touching the headlight assembly. The catch can was delivered yesterday and it was raining all afternoon, so I didn't get to play with it much.

Most of my wrench time has been on old aircooled VWs and the original Insight, both of which had fairly simple and easy ICEs to work on. Here's the PVC hose:

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I assume that the catch can plumbing should tap the line in the upper most section of the PVC hose as orientated on the parts diagram, but I'd appreciate confirmation.

Thanks in advance for any tips.
 

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OK, my curiosity has overwhelmed the chance that I'll come across as sarcastic.

You will spend most of your time in EV mode so why bother with a catch can?
 

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OK, my curiosity has overwhelmed the chance that I'll come across as sarcastic.

You will spend most of your time in EV mode so why bother with a catch can?
I keep cars a really long time (I traded in a MY 2000 Insight for the Volt).

Currently I'm at 60/40 electric to ICE.

Often when I am using the ICE, the car is pulling a kayak trailer (about 500 pounds), so my ICE is under a little more load than average.

I live in a very humid environment which leads to more gunk in the intake than in dryer climates.

I've had good experience with catch cans in the past.
 

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Thanks for the reasons.
 

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While I've seen plenty of catch can solutions with older cars, is it proven to work on GDI systems or is it a hold over?
 

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You may trigger a Check Engine Light for a PCV system fault after you install it. It also may void your warranty, especially if you have to cut into the existing lines.
 

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While I've seen plenty of catch can solutions with older cars, is it proven to work on GDI systems or is it a hold over?
Because Gen 2 Volts have not racked up lots of ICE miles (and the Gen 1 didn't have DI), I spent some time reading Chevy Cruze forums. Some swear by catch cans and others say it's snake oil, so I would not go as far as to say it's been "proven" to work. As best I can tell, on a similar DI motor from the same manufacturer, catch cans are collecting gunk and not throwing CELs when properly installed. That's enough for me to continue investigating.

When you mention older cars, the VW Thing has a large oil bath air cleaner which acts as a built-in catch can. Seeing some of the gunk that would accumulate after a long highway run is what prompted me to consider catch cans in general. Of course Pumpkin's motor is perpetually tired and I get more blow by than you'd see on a modern engine, but it's still eye opening.
 

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You may trigger a Check Engine Light for a PCV system fault after you install it. It also may void your warranty, especially if you have to cut into the existing lines.
I have not had that happen in the past with previous catch can installs and I don't see CELs or warranty issues on the Cruze forums, so I think it's a fairly low risk mod if done properly.

Obviously there's no guarantees, but this is not a crazy mod.
 

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You may trigger a Check Engine Light for a PCV system fault after you install it. It also may void your warranty, especially if you have to cut into the existing lines.
Do you have ANY facts to back that up? Please tell us how the engine computer would even know there is a catch can on a breather line. Also do you actually work on your cars or just do as the dealer tells you?
 

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Do you have ANY facts to back that up? Please tell us how the engine computer would even know there is a catch can on a breather line. Also do you actually work on your cars or just do as the dealer tells you?
You may trigger a Check Engine Light for a PCV system fault after you install it. It also may void your warranty, especially if you have to cut into the existing lines.
If you don't install it correctly it will trigger a P0171 CEL for a vacuum leak. Key word here is "CORRECTLY".
 

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To be clear, I'm not advocating for the universal use of a catch can. I just think it makes since for my usage pattern and average length of ownership. Also, I think that with a little care, it is a low risk modification.

Back to figuring out the proper installation. It appears that the Volt has a fresh air PCV valve and a foul air PCV valve. I'm assuming that the foul air PCV valve is the one that I want to locate in terms of tapping the hose for the catch can. I don't think that I've wrenched on a car with multiple PVC valves that was not forced induction (I keep cars forever, so perhaps I'm just behind the times, but I thought this was one of the many "special" features of the 1.8T VW motor that I drove for years).

I assume that the foul air PCV valve is going to be connected to the intake manifold. Unfortunately I cannot find a diagram on GM Parts Direct for these two PCV valves, so I'm guessing here as to location. Worst case is that I'll find these PCV valves and check the part numbers, but if anyone has any insight, it would be appreciated.
 

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I run a performance automotive shop. I have installed hundreds of catch cans and air/oil separators on all sorts of different vehicles. I've written blogs on how important it is to have a catch can or air/oil separator on a DI engine. I perform walnut blasting intake valve cleaning on DI engines. In as little as 15,000 miles we see significant buildup on some engines.

Having said that, I see no need to add one to my Volt.

We see significant buildup and sludge as early as 15,000 miles... on a modified vehicle driven by a kid who short cycles the engine and floors it everywhere, even when it's cold, and only puts supermarket 85 octane in it.

On a more gently driven vehicle, it usually takes 30,000 miles before the build up begins to have a negative effect on the engine.

I've had my Volt for about 8 months and I've put about 12,000 miles on it. Only about 1800 are on gas.
A regular gas engine vehicle will have hundreds of hours of running time to get 1800 miles (Unless they drove 30hrs straight at 60mph...) A Volt ICE likely has less than 30hrs of actual runtime to get that 1800 miles as there is a lot of regen battery involved.

So the 1800 gas miles on my volt is a very short amount of running time. I figure over the life of the vehicle, the ICE may only see the equivalent of 20,000 miles worth of regular car run time. It'll never get enough run time to get a significant amount of buildup. It's not worth messing with.



The proper way to install the catch can would be to find any vacuum hoses on the air intake between the air filter and the throttle body. The catch can, or cans, must go between the intake and the hose/s.
Everything must be air tight to make sure you don't mess up the air flow sensors. Most cheap catch can kits leak like a sieve.
 

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Thanks for the insight. I already have about 12,000 ICE miles on my Volt and as I mentioned before, I keep cars a long time. I also frequently haul a sailing kayak (kayak weighs 250 lbs and the trailer another 250 lbs).

I've run the original oil bath air cleaner on my VW Thing for ages. When I lived in dry NM, I'd pick up a fair amount of silica in the oil bath, but otherwise the oil looked fine. Here in humid Florida, I can pick up lots of moisture in the oil bath (granted it's a tired engine and it doesn't get used on highway much anymore). I'm concerned about the moisture, not oil vapors. It's practically impossible to abuse the Volt's ICE and as long as I use quality oil I shouldn't see a problem with the backside of the valves from oil, but it's unavoidable to have lots of water vapor flowing through the PCV system here.

It appears that you are in Colorado where there isn't much humidity, but you certainly possess much more automotive knowledge than I have. Does my usage/ownership/environmental parameters change your analysis? I know that extrapolating from a 50 year old aircooled VW motor to the Volt is like comparing apples to watermelons, so I'm completely open to being told I'm wrong here. If a high amount of water vapor without much oil won't cause a problem on the backside of the valves, then I may put the catch can back on the shelf.

Thanks again for sharing the knowledge.

ETA I put lots of miles on the car about 8 months out of the year when the weather is nice down here, but during the summer it's too stormy to get out on the water much, so the Volt is pretty much a local commuter car for four months. I revived this topic because the car recently went in to EMM and stumbled pretty badly when the ICE first turned on. It didn't throw a CEL, but it got me thinking (never a good thing).
 

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As diplomatically as possible, I have to correct you on your “proper catch can installation” description. A catch can doesn’t go inline with any vacuum lines that go between the air filter and throttle body. As a matter of fact the catch can is only placed inline with the PCV line that runs to the manifold, speaking specifically about NA cars in this case.

As for choosing a catch can, you gotta be mindful of the design. The majority of cheap, and even expensive catch cans are half heartedly designed. One look at an industrial air/oil separator will show that it takes more than can with maybe a couple baffles to clean the PCV stream.

There are a few common ways for oil to be removed from the air stream:
Velocity. By having the air pass through a large can, the velocity drops and droplets can just fall out.
Baffles. The air/oil is forced to make turns and the oil droplets can’t make the turns without hitting the sides.
Impingement. Much like baffles, but a step further. The air stream is directed at a shape that it has to bounce off of.
Coalescence. The air stream passes through a filter-like material where the oil just sticks to it and gravity pulls it down.
Cooling. Cool air will hold less vapor. Cooling the air stream will make any of the above methods more effective.

If you have your heart set on a catch can, look for one that incorporates at least a few of these features.

All that said, I’m not a huge fan of catch cans. Mostly because they need to be emptied. I’d rather do a port cleaning when needed. I’ve had quite a few DI cars, and never had a problem that stemmed from intake port build up. If I had, I’d just clean them.
 

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Thanks for the insights Dannicus. I wonder if a catch can will age the oil faster as it restricts PVC flow and causes more blow-bys inside cranckcase. This will be a problem with Volt as we don't change oil as often.
 

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Thanks for the insights Dannicus. I wonder if a catch can will age the oil faster as it restricts PVC flow and causes more blow-bys inside cranckcase. This will be a problem with Volt as we don't change oil as often.
How does a catch can restrict PVC flow? I've never experienced that as long as the can is emptied periodically.
 

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How does a catch can restrict PVC flow? I've never experienced that as long as the can is emptied periodically.
Well instead of a straight pipe you will have some kind of an oil filtering mechanism on the way with the catch can. Air flow will be slower. How slow? I don't know but slower for sure.
 

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Well instead of a straight pipe you will have some kind of an oil filtering mechanism on the way with the catch can. Air flow will be slower. How slow? I don't know but slower for sure.
There's not an oil filtering mechanism generally ... it works with just baffles and a decrease in pressure due to the volume of the can itself. I don't think that a proper catch can restricts flow unless you allow it to get filled up with gunk.
 
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