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Oil Catch Can - is it needed?

Twilightwheelin

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Couple things: its not blow by. Blow by is a symptom of poorly seated rings and piston and or skirt problems. Its crank case venting back into the top end. And being the 3.6 is not DI its fine . Fuel washes it all down. Also if you use better synthetic oils, they are less evaporative. You will not need to worry about it. 2.0 is a different story because that is DI, vvt, Cooled Egr and pcv loop.
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ShadowsPapa

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Hard to call it an "issue" when many people don't really have it as a "problem".
For example - if you drive 3,000 miles and the oil level doesn't drop on the stick - is there too much oil being burned?
If what you catch is milky looking, more like chocolate milk - it indicates a fair amount of what was caught was moisture - water. So if you catch 4 ounces, only part of that is oil.
If there is no knock of detonation and the spark plugs stay very clean with no carbon build-up, is there too much oil getting into the chamber?
The amount some say is being caught should mean your oil level would drop by half a quart in 5,000 miles - mine does not.
If it was ALL oil...........since the engine isn't making oil as it runs, then for oil to be up there, it can't be down below.
I've never seen it as an issue except on modified engines like my 360 or the high-compression 390 with a performance cam. That was an issue and yes, oil was being run into the intake.

If you have oil pool in the intake, you have a problem. Those that see this - or the oil goes down more like a 1970 engine, there's an issue to deal with.
It's interesting that not all do.
YMMV
Since these don't use any true valve like a PVC that cuts off flow under high vacuum conditions, part of the variation could be driving habits and use of the truck.

Diesels - since oil in the combustion chamber absolutely negatively impacts gas engines, it's a problem for them, but I don't know it would be the same for diesel.
 

ShadowsPapa

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Couple things: its not blow by. Blow by is a symptom of poorly seated rings and piston and or skirt problems. Its crank case venting back into the top end. And being the 3.6 is not DI its fine . Fuel washes it all down. Also if you use better synthetic oils, they are less evaporative. You will not need to worry about it. 2.0 is a different story because that is DI, vvt, Cooled Egr and pcv loop.
Maybe I use better oils or whatever, but I've never had any issue with ANY Jeep engine. I have 3 Jeeps and 4 vehicles with Jeep engines in them - none have any such "problem"
Again, I can go out and check the oil level at 3,000 miles, or more, and it won't be down any appreciable amount. And the spark plugs look almost new. I have 33,000 in the original plugs in one of my 4.0s and they are worn, but clean, no carbon, and they are not dark - more of an off-white color. .
There's a few non-trained, non-mechanics relying on marketing telling them what they need, or "I read it on the internet"

Engines need to run a vacuum in the crankcase - check the racing catalogs, there are even vacuum pumps sold for when you can't evacuate the crankcase with engine vacuum alone due to cam and other factors. That vacuum helps prevent leaks, yes - but also promotes ring sealing as it's the difference between the pressure above the rings vs. below the rings that cause them to be force out against the cylinder wall. Reduce that difference and you reduce ring sealing.
 

Shultz01

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Had one on my JL and moved it over to my new JT. They both had about the same amount of blow by caught by the can. I check it about once per month and it has about 1/4 cup of oil in it each time. Glad I have it installed.

Coincidentally, my wife's Ford Explorer ST has one and it's useless...zero blow by.
 

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Had one on my JL and moved it over to my new JT. They both had about the same amount of blow by caught by the can. I check it about once per month and it has about 1/4 cup of oil in it each time. Glad I have it installed.

Coincidentally, my wife's Ford Explorer ST has one and it's useless...zero blow by.
That's not "blow-by"..............
 

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Have my Mishimoto catch can installed. Great complete kit.
Had a catch can on my 07 Dodge SRT as well and yes, if you don't want to ingest oil into your intake then it's a great addition.
Plane on keeping the rig (my last new rig) so doing everything I can to keep it as nice as possible and long lasting.

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Trlr8tdd

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After pulling the lower intake on my 13 Rubi, I’m putting baffled catch cans in both jeeps. It certainly doesn’t hurt Anything keeping that muck out of the engine. My lower runners and heads were coated in a black muck. After research, thinking I had serious engine problems, found it’s normal at 155K miles. I’ve always used catch cans on my performance cars to gain better air fuel ratios and this is no different. My Harley has had the same mod first time I pulled the air cleaner off and saw the tell tail trail of fresh oil. Heck, even my boat has one.
Anything other than Air and Fuel in the intake takes up space the air and fuel need, oil lowers the octane rating possibly causing light spark knock then the sensors retard timing and down goes horsepower.
 

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2k miles, half full of this junk.

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KurtP

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I use one, but i use one all the time to help prevent detonation.

the poster above about oils is correct. My catch can had a lot more oil at my 1500mile mark when i did a change to M1 extended 0w20 than it did when i drained it again at 5k.
 

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one2doo

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I have one def needed.
 

DLAW

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Intriguing mod for most. I would say it's only a must have for rock crawlers who get into extreme inclines. That's just because you suck up an unhealthy dose of fluid from the crankcase by tipping it. People running catch cans BECAUSE they rock crawl, are checking the can EVERY day they got into an extreme angle.

I like to keep things clean, and I will probably install one before it hits 1k miles. But here is why it may NOT be needed: The Pentastar engine is currently multi point injection, not direct injection. Gasoline keeps the valves clean and our engine is spraying it in a way where we shouldn't be seeing a lot of carbon build up. "Direct injection" without the modern smart cleaning cycles would spray the gasoline past the valves, and therefore the valves get too much carbon build up when coupled with a PCV.
What you are seeing in a catch can is mostly water. It's literally moisture from the air the engine breathes. It gets mixed with some oil, some exhaust and then turns into chocolate milk. I'm seeing people here posting photos of dumping a cup of fluid every 2k miles. That's almost a rate of a quart per oil change. If that was all oil, our engines would be in serious need of oil top offs. We should NOT need an oil top off in-between oil changes. This isn't the 1980s.

Personally, I hate the idea of running chocolate milk through the air intake, but is going to reduce the life of the engine? Not a whole lot of science warranting that.

I'm on the fence about whether or not it's really needed. but I'll install one because I like to tinker and have OCD. It will also give me an excuse to pop the hood more often.

To each their own! Install one if you want. Absolutely no harm in doing so as long as you don't forget about it. Just make sure you do NOT get a vented one. Venting the catch can defeats the vacuum pressure in the hoses and is terrible for the crankcase.
 

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Saw a great YouTube video the other AM. Some of the older VWs had a weird direct injection set up that allowed fowling o f the valves. Not so sure our 3.6 need it but am open to educations.

Guy is a little crazy but he knows his stuff.
 

bring44

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just from research search online, my other project cars are all turbo'd so im used to blow by issues. I decided to do some reading up on it for these motors and found some people having some issues. granted most are on the older 3.6 in the jk systems but that's why I was asking if anyone had any issues with these newer designed motors.
fixed it for ya!
 

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Saw a great YouTube video the other AM. Some of the older VWs had a weird direct injection set up that allowed fowling o f the valves. Not so sure our 3.6 need it but am open to educations.

Guy is a little crazy but he knows his stuff.
Not watching a Scotty Kilmer video. He’s a nut job! If you buy in to his rhetoric, you should immediately sell you Jeep (his recommendation).
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