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.
 

ShadowsPapa

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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"..............
 

Willys2Gladiator

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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.

PXL_20201126_211131946.jpg
 

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