Catch can flow discussion

[L8T BURB]

I'm intrigued by catch cans and what they can do, why they exist, etc. Generally speaking, I like to challenge things with questions, only in an attempt to gain a better understanding of something that's new (to me).

With that said, has anyone ever sent their catch can gatherings to Blackstone or any similar oil analysis company to be evaluated? I've seen some online say they believe the catch can gatherings are mostly fuel, with only a very small part of it being oil. That being why most people report the can gatherings look quite thin.

Thoughts? As stated before, I truly am intrigued by these things, but I'm thinking if some of those who have the catch cans would be willing to send their catch can gatherings for analysis then we could better position ourselves to either have more trust in these, or possibly push them off as unnecessary add-ons.

 

[iamdub]

I'm intrigued by catch cans and what they can do, why they exist, etc. Generally speaking, I like to challenge things with questions, only in an attempt to gain a better understanding of something that's new (to me).

With that said, has anyone ever sent their catch can gatherings to Blackstone or any similar oil analysis company to be evaluated? I've seen some online say they believe the catch can gatherings are mostly fuel, with only a very small part of it being oil. That being why most people report the can gatherings look quite thin.

It's just oil that gets blown from inside the engine. If there's fuel in it, then the oil circulating through the engine has fuel in it. If there's fuel in the oil beyond a certain, acceptable amount, then the engine is worn, damaged or not running properly. The only way I'd see the oil in the catch can being any different than what's in the crankcase is from something (fuel or moisture) being introduced into the PCV system from the top end, like just under the valve cover. If the oil in the catch can is thinned from being mixed with fuel, then it's likely thinned with fuel in the crankcase.

Thoughts? As stated before, I truly am intrigued by these things, but I'm thinking if some of those who have the catch cans would be willing to send their catch can gatherings for analysis then we could better position ourselves to either have more trust in these, or possibly push them off as unnecessary add-ons.

They have been proven time and again to be, at the very least, a "better safe than sorry" addition. They don't need to be proven any further to garner trust. They can do no harm if installed and later found to not be needed. If anything, it's a monitoring device if you just so happen to have an engine that moves no oil through the PCV system.

There are instances where they collect a bunch of moisture. Aside from the engine consuming moisture due to an internal coolant leak, this is environmental due to ambient temperatures, humidity and drive cycles. All this means to me is that's moisture (and oil) not being dumped into your engine and you should get a larger catch can or drain yours more often if it fills up. Regardless, its still doing its job of keeping stuff out of the engine's induction side.

 

[George B]

Goin all mil-spec on it.




@Just Fishing style!

You know it

 

[L8T BURB]

It's just oil that gets blown from inside the engine. If there's fuel in it, then the oil circulating through the engine has fuel in it. If there's fuel in the oil beyond a certain, acceptable amount, then the engine is worn, damaged or not running properly. The only way I'd see the oil in the catch can being any different than what's in the crankcase is from something (fuel or moisture) being introduced into the PCV system from the top end, like just under the valve cover. If the oil in the catch can is thinned from being mixed with fuel, then it's likely thinned with fuel in the crankcase.




They have been proven time and again to be, at the very least, a "better safe than sorry" addition. They don't need to be proven any further to garner trust. They can do no harm if installed and later found to not be needed. If anything, it's a monitoring device if you just so happen to have an engine that moves no oil through the PCV system.

There are instances where they collect a bunch of moisture. Aside from the engine consuming moisture due to an internal coolant leak, this is environmental due to ambient temperatures, humidity and drive cycles. All this means to me is that's moisture (and oil) not being dumped into your engine and you should get a larger catch can or drain yours more often if it fills up. Regardless, its still doing its job of keeping stuff out of the engine's induction side.

Awesome explanation! Thanks!!

 

[Big Mama]

Great topic. Other than Joe’s post I didn’t see much about how much “oil” is being seen between oil changes. And, is that a good measure of if it actually working well given the different configurations. I also have the Amazon can but it’s a fancy anodized blue and has a dipstick.

 

[iamdub]

Great topic. Other than Joe’s post I didn’t see much about how much “oil” is being seen between oil changes. And, is that a good measure of if it actually working well given the different configurations. I also have the Amazon can but it’s a fancy anodized blue and has a dipstick.

If it doesn't catch much, then either it's not working so well or your engine isn't passing much oil. I'd check the can's outlet hose for oil to see if the oil is just passing through the can. It'd have to be a really crappy design to not catch anything. Like, no filter and just some poorly-designed baffles. If you're filling the can frequently, that's bittersweet. It means your can is keeping a lot of oil from being burned. But it also means you need to take action to keep the oil inside the engine in the first place. There, again, it's at least a monitoring device and worth the $25 or more invested to have answers.





Mine seemed to work pretty well. I forget the exact amounts (I'm sure it's documented in my thread somewhere), but I consistently drained something like two ounces at every 5K mile OCI. A while later, I saw Amazon listings for catch cans having "high efficiency stainless steel filtration media" that were really just those scouring pads. I added one at my next oil change. From then on, I consistently drained three ounces.

Side note: This was with AFM disabled and mine already had the updated valve cover. Since deleting AFM, which included blocking off everything to make the block like a Gen 3, I've drained 1.5-2 ounces every time. The cam, the much more frequent 6K spins, much more sustained WOT, etc. all would have positive and negative effects on the engine's vacuum and PCV pressures. So, if I drove mine like @donjetman drives his, I'd probably have less than an ounce.

 

[Big Mama]

Good points. I’ll measure it this time. She’s due for an oil change. After I pull the scrubber out there’s enough to coat the bottom of the can. I’d guess an ounce or so. Big Mama doesn’t have AFM so it sounds like she’s doing ok. For giggles I’ll add one to the Sierra I got in January. It has AFM and is also a 6.2.

 

[donjetman]

Top one is the oil after 5k miles from the cheap cc on our 191k mile 07 Yukon.
Bottom is the oil after 5k miles from the pricie cc on our 68k mile 02 Corvette.

 

[MWD_CTSV]

I bought the JLT and the install seemed backwards to me so I checked the instructions for any indication of inlet filter. So in the end I switched the sides so the filter was on the intake side.

JLT is likely correct that the best filter placement is on the valve cover side. However, even with my backwards install, it still collects oil quite well.

 

[iamdub]

So far, it seems the consensus is to have the inlet hit the filter. That's what the "big brands", which I'd be inclined to believe have put more R&D into their products than the Chi-clones, seem to agree on. But that's not to say that having it reversed won't work, either.

I'm gonna stick to my assessment that make a whole lot of difference, assuming you have proper coalescing media. But, where it would matter is if you're trying to keep something in the engine (like oil) and just catch what makes it through versus trying to vacate and capture something (like moisture). If just oil, inlet goes directly to filter. If moisture, inlet goes to reservoir.