Catch Cans - What's the Verdict?

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27
Location
USA
Thread starter
Looking around the GM boards, it seems the L86 in my Yukon has some coking problems. I've seen some photos after under 10k miles that are concerning. Looking into installing a catch can. The GM forums are all over the place on the opinions of them.... "Trust the engineers," "Have to have one," "GM will void your warranty," all sorts of stuff. I'm curious what the thoughts are here on them? $200 piece of mind, snake oil, or truly an intake valve saver?
 
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24,425
Location
Central Florida
I'd install one if I have a vehicle known for sucking lots of oil into intake. Lots of videos on YouTube of people draining their can after 5K miles. Obviously remove can if you need warranty work....
 
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5,124
Location
Atlanta,GA
The appearance of build up does not by default equate to poor performance. Some engines are more sensitive vs others. For example the inspection interval for the BMW N55 (~8 yr old engine design) is 100k miles. If the user forgets to drain the can and because the can is located outside the engine in really cold climates there's a real issue of water condensate turning into ice thereby causing a blockage. Basically it's a solution in search of a problem. It's a great product for those who are obsessive or need an excuse to tinker for the sake of tinkering
 
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827
Location
Texas, USA
The reason the auto makers don't install one is entirely because of cost, and maintenance. Every penny they can squeeze out of the build budget is a penny they can spend on executive salaries. And no auto-maker is going to be the first to add a new maintenance item to a vehicle. Catch cans are far from snake oil, as two of my vehicles have already proven. The Ford Performance catch can I put on my '18 Mustang proved its worth at every OCI when I dumped several ounces of foul-smelling fluid out of it. The JLT catch can I just installed on my Focus ST 3 weeks ago already has 1/4 ounce sitting in the bottom of it, as I checked it for the first time this morning. Below is what you can expect if you don't have something taking the oil mist out of the PCV stream before it hits your intake. A valve in my Focus ST, at 24,000 miles:

Valve2.JPG
 
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133
Location
YYC
Generally they're not needed and a waste of money, I'd only install on a engine with known PCV blow by issues. A lot of the videos that show all the gunk that gets collected in the catch can look a lot worse than it really is as most of the gunk that's collected is generally condensation from the engine which is normal. Pulling blow by gases back into the intake is not an ideal solution but it's a compromise made for emissions reasons and for practicality. Catch cans can also cause problems as pointed out with the freezing issue, they also add a restriction to the escaping blow by gases which can cause oil leaks in other places in older diesel engines.
 
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4,534
Location
Pittsburgh,PA U.S.A.
I am still on the fence regarding catch cans. Exhaust feedback is part of the problem, and they do nothing to get rid of that. And some of the best ones have a cindered brass screen, but if that clogs up you could blow the crank seals. There are Youtube videos about catch cans and some of them bring up the point that there are a lot of direct injection engines without port injection that have a lot of miles on them and there are not a lot of engines requiring intake valve cleaning.
 
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Messages
27
Location
USA
Thread starter
The tough part is it's all anecdotal info right now. No one has had two identical engines, run one with a can and one without, and compared them. I am a bit nervous with my Yukon given I plan to keep it for a very long time, so I would like to maintain its performance (clean valves helping here) as long as possible. Last thing I want is to get up to 100k miles and be looking at a big cost to get the valves cleaned. Preventative maintenance is always cheaper, etc. However, my other worry is the catch can potentially causing damage if something went wrong. As long as I remember to empty it, is there any way that it can cause damage to the engine? I would also remove it prior to taking the truck to the dealer for any work.
 
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1,723
Location
Michigan
Originally Posted by shimps1
As long as I remember to empty it, is there any way that it can cause damage to the engine?
What's the worst that can happen? When it gets really cold, moisture that has condensed in the line freezes, plugging the PCV system, causing excessive crankcase pressure, and blowing a front or rear crank seal. That's about the worst that can happen.
 
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524
Location
Lead, South Dakota
Your PCV system is already precisely tuned by actual engineers and most cars have some sort of separator on them anyway. Adding a catch can does nothing, at best, and at worst can cause problems. Most of what they're catching is water vapor, with tiny amounts of oil and fuel. They were useful on sloppy old carbureted motors with tolerances the size of a barn door, but there's no point on a precisely tuned, computer controlled engine of today.
 
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Messages
761
Location
FL
Originally Posted by littlehulkster
Your PCV system is already precisely tuned by actual engineers and most cars have some sort of separator on them anyway. Adding a catch can does nothing, at best, and at worst can cause problems. Most of what they're catching is water vapor, with tiny amounts of oil and fuel. They were useful on sloppy old carbureted motors with tolerances the size of a barn door, but there's no point on a precisely tuned, computer controlled engine of today.
In other words: you're just adding weight to the vehicle. cheers
 
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774
Location
E. Tennessee
FWIW: I have them on my turbo 2.0L GDI engine. I get about 2oz of liquid nastiness for every 4K mile oil change. I'm glad this isn't going into my intake as well as lowering the octane level of my fuel (I run 93 octane and a nice tune which requires it). Worked great for me!
 
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8,778
Location
Houston, TX
I installed one on my Rubicon and has about an ounce of oil in it after 400 miles. Plenty of opinions either way, but for me, I do not want the oil it has caught from going into the intake and the combustion chamber.
 
Messages
71
Location
NM, USA
Quote
FWIW: I have them on my turbo 2.0L GDI engine. I get about 2oz of liquid nastiness for every 4K mile oil change. I'm glad this isn't going into my intake as well as lowering the octane level of my fuel (I run 93 octane and a nice tune which requires it). Worked great for me!
guess your engine is not 'precisely tuned' regarding to littlehulkster's post:
Quote
there's no point on a precisely tuned, computer controlled engine of today
 
Messages
524
Location
Lead, South Dakota
Originally Posted by StarCaller
Quote
FWIW: I have them on my turbo 2.0L GDI engine. I get about 2oz of liquid nastiness for every 4K mile oil change. I'm glad this isn't going into my intake as well as lowering the octane level of my fuel (I run 93 octane and a nice tune which requires it). Worked great for me!
guess your engine is not 'precisely tuned' regarding to littlehulkster's post:
Quote
there's no point on a precisely tuned, computer controlled engine of today
That or it's 1.8oz of water vapor and .2oz of oil and gas blowby.
 
Messages
1,663
Location
WA
I did some research after our first ever DI car (never again if I can help) ... anyway, decided not to bother with a catch can. Also after approx 70K miles, the PCV and hoses were very clean so it didn't seem like there was much of anything to be "caught". I use good syn oils including M1 EP with 6-7K mile oci so that may have helped.
 

wtd

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2,477
Location
southwest Mo.
I run them on my 14 Mustang GT, my fiancée's 07 Mustang GT, and her 2017 F150. I've run mine on my car for almost 7 years and on her Mustang for longer than that with no issues. All of the engines in these vehicles pull a lot of oil through the PVC system and before the catch cans, the outlet lines going into the intake was soaked with liquid oil. On her Mustang when it was fairly new with low mileage, it was smoking blue smoke on startup. I went to the Mustang forums and asked about it. Multiple people said to install a catch can to stop it. We did and it worked. No more blue smoke, even to this day. I put a can on my car right after buying it new so it's ran one the entire time.
 
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