catch can research shows it's worthless

[kiteman]

i posted this on a catch can thread in the v6 forum, but really my research applies specifically to the lsx motors, though i think the gist is the same for any engine. anyway, this is worth a read. take note of the c4c5 poster's title: "gm world class certified technician." there are two other mechanics on the post that agree the catch can is a waste of time and money.

http://corvettemechanic.com/forum/3841-catch-can.html

Catch cans were invented because of someone wanting to make money, its that simple.

PCV systems are ALWAYS not enough at high rpm usage. This is why this occurs. The higher the engine revs, the more pressure occurs in the crankcase, which the valve will not ventilate. So, the residual oil vapor comes up through the fresh air hose to the intake.

Someone just thought it would be a great idea to make a dollar off it.

I would like SOMEONE to show me ONE ENGINE/CAR MANUFACTURER THAT MAKES ONE. This is because there is no need.

The fact that your running synthetic oil, only allows the condensed oil that is there to run into your engine.

And you burn it.

There is no harm to your intake manifold, throttle body or engine as this occurs.

key note is that you burn it. people see their catch can filled with oil, or even see it inside their intake and then freak out. but many don't realize as that gets sucked into your engine (that is operating at very high temperatures), the type of oil that is going into the engine via the intake is burned up immediately. the result...it sounds to me, is harmless to your engine. thoughts?

[DietCoke]

It is harmless, correct. The catch can does keep your intake tract clean, however, and will prevent a lot of blow-by from reaching the clean tract on more radical setups (big inch, big overlap, or FI).

Venting the valve covers is necessary to supplement the LS pcv system, as well.

[CyberDan]

But is the catchcan hurting performance? If not, I like the piece of mind I get by having one on my car.

[67motorcat]

I have always suspected the Catch Can was not really neccessary.

However,I have one on my car with the thought that it could only help and does not harm anything.

Plus I think it looks cool.

I don't have one on my 5.3 Silverado with almost 200k on it and it runs like new

[EricSS]

I'm not sure that I would agree that linking one thread on another forum where someone says it is unnecessary truly qualifies as "research."

[kiteman]

Originally Posted by EricSS

I'm not sure that I would agree that linking one thread on another forum where someone says it is unnecessary truly qualifies as "research."

do you know what that website is?

Thank you for visiting the Corvettemechanic Community. CM is a corvette enthusiast website with a staff of fully certified GM and ASE Master Technicians who service these great vehicles. We will assist you in a timely manner finding the correct resolution to any issues you may have with your vehicle. We provide the most up-to-date information available for all period year Corvettes. So whether you drive a 1966 corvette or a new ZR1, we are here to help you. Remember as technicians we have access to information most persons don't.

i'd say that is not only relevant (lsx engines), but pretty damn concrete evidence/research.

the tech makes a wise point: why has no car manufacturer ever made a catch can of their own? you'd think if it were a problem not having one, they would either come up with a solution or warranty the problems caused by the blow-by. seems pretty logical to me

[EricSS]

Originally Posted by kiteman

well, the guy works for GM and is a pretty reputable source from what i know about that forum. i'm sure there are others out there, but this was the most relative (lsx motors) and concrete info i could find.

the tech makes a wise point: why has no car manufacturer ever made a catch can of their own? you'd think if it were a problem not having one, they would either come up with a solution or warranty the problems caused by the blow-by. seems pretty logical to me

Then why do they offer/ recommend a cleaning at ~20k miles? If you were a dealer and could make 100 bucks off a part once or several hundred multiple times over the life of a vehicle which would you choose?

[bmorecam]

Just not too long ago I see an article how not having a catch can is bad and now I see someone write how having a catch can is just a waste of money.

I did give this some thoughts couple times in my lifetime or as long as I have known about catch cans. As cheap as it cost to put a catch can in every manufactured vehicle wouldn't the mfg's do this if infact something as simple as a catch can really does help prolong your engine?

Im more confused now LOL.

[Blueclyde]

Manufacturers need to run closed crankcase vent systems due to emission regulations That is why you do not see them. They are harmless but really are a waste of money.

[BLACK10]

yea, let me just run multiple qrts of oil through my engine....no big deal, it just runs on oil and gas. thats what i want. a two stroke engine.

[Apex Motorsports]

For the average car owner that tools around town for 3-7 years and trades in their car it is not necessary. For the automotive manufacturers it is a simple business decision. Do you incur increased costs ($100 isn't much until you multiply it times 100,000+ units a year and realize that is right out of your profit) and add a "catch can" to fix something that will not be a real issue until after your warranty is expired? Do you add a system that requires the owner to do a maintenance process they are not familiar with and possibly ignore (draining the can) that could cause an issue within the term of your warranty? The answer is no.

Here is an excerpt from a conversation that Tracy (SC2150) and I had a few weeks ago.

Dodge 6.1 Hemi w/3000 miles on it:


Forged piston with only 6-8 runs down the track with no evac system. Excess crankcase pressure plus nitrous lifted the ringland and the carbon build up was that quick. The oil ingestion from no proper evac and catchcan system caused alot of the detonation that melted the top ringland enough to allow it to lift.



C6 Z06 w/9k miles on it...bone stock:


Typical piston top after running for 50-100k w/no oil separating can:


Cylinder head intake ports:


The DI engines are very problematic to the build up as no fuel passes the intake valves to help keep them clean (Mobile, shell commercials "gunk") so the V6 it is critical to have one installed right from new. We see the Mini Cooper with needing the cylinder head removed to manually clean in as little as 25-50k miles.

[navyblueSS]

A catch can has been a recommended add on to the ls motors for years, it is cheap insurance in my opinion.

[DietCoke]

Originally Posted by Apex Chase

For the average car owner that tools around town for 3-7 years and trades in their car it is not necessary. For the automotive manufacturers it is a simple business decision. Do you incur increased costs ($100 isn't much until you multiply it times 100,000+ units a year and realize that is right out of your profit) and add a "catch can" to fix something that will not be a real issue until after your warranty is expired? Do you add a system that requires the owner to do a maintenance process they are not familiar with and possibly ignore (draining the can) that could cause an issue within the term of your warranty? The answer is no.

Here is an excerpt from a conversation that Tracy from RevXtreme and I had a few weeks ago.

A catch can is not an EVAC system though. It has nothing to do with the PCV, it simply catches the oil vapor that would naturally just pass completely through.

You will need to vent the valve cover. The way it works, is the valley cover is hooked into the vacuum side of the intake manifold (behind the throttle plate) which draws the air out of the valley/motor. The clean air is being drawn from the motor is pulled from the top of the motor, preferably the valve covers. They are hooked into the throttlebody where clean, metered air is drawn. This creates a cycle, by which internal air of the motor is flushed with clean air.

'Air enters intake filters, travels through MAF, some gets drawn by the PCV infront of the throttleplate into the valve covers, cycles down into the crankcase, gets sucked into the valley, through the LS3 valley cover, and into the intake, behind the throttleplate (where its sucking like a straw), into the combustion chambers and out of the exhaust.

Without this vacuum circulation you will not effectively clear out the crankcase, nor, will you be able to properly tune with a MAF if it is not in the closed loop like described.'

The catch can simply sits in between this cycle. It is neither important nor necessary, it just absorbs most of the vapor, but has nothing to do with the actual pressure venting of the system.

[Rangore]

In regards to a post that mentioned maintenance...how hard is it to drain, and how often should it be drained? I'm considering putting one on, but I don't know whether I should. Does it matter that I live in Minnesota, so will the can contents freeze? I would not think so, but that is something to consider around here.