Catch Can - weird (but good) results


PetroleumJunkie412

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So, changed valve cover gaskets recently. Noticed an undue amount of oil in the pcv vac lines coming off the valve covers, which seemed odd to me. New pcv 4000-5000 miles ago; it still seemed to be working fine.

Just for poops and laughs, tried an experiment.

Ordered a $30 amazon catch can with a filter. Took the vac line off the driver's side valve cover, and installed the filter from the kit on the right angle elbow coming off the cover. Capped the breather tube port on the throttle body.

Installed catch can under the throttle cable bracket. Figured out that the lightweight filter foam that comes in 100mL antibody/serum shipping boxes is the exact same size as the "filter" canister on the "out" side of the Amazon can. Cut off a slice and stuck it in. Fluffed up a stainless steel pot scrubber and put it in the body of the can. Plumbed can backwards so that the pcv went into the "out" side of the can, and the "in" side attached back to the pcv port in the plenum. Hooked up backwards so that the engine vacuum would draw through the filter on the driver's side via the pcv, gasses would flow into the stainless media, then foam filter (hopefully blocking stainless steel shrapnel from entering the throttle body), then exit the can into the pcv port in the plenum.

My truck has always ping-ed under strain on hills, especially the ones in North Pittsburgh.

I DID NOT clean anything. Just hooked up the can. Went for a drive. ZERO ping. I mean zero. Nada. Zip. Zilch. Idle usually was at 1000-1100 when the engine was at temperature. Now sits at 800-900, and all hesitation and roughness is gone. Exhaust smells noticeably different. Noticeable new "pep" when pulling out from a stop. Checked the can after 50-ish miles. The media smells like a fraternity couch was thrown into a volcano, and is oily.

Anyone else try this? It seems my 2.9 was extremely sensitive to oil vapors/pcv crap/the factory dual vacuum setup that didn't make sense to me.

Feel free to criticize.
I'll bet $1 at least one person will respond with, "put a 4.0 in it"

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BrutalPanda

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Get some pictures on here for us

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PetroleumJunkie412

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As requested!

Photos are of the crap amazon can, the backwards plumbing, and inside of the oil catch. The stench is indescribable.

Oh, something else worth noting - my truck would roll white/grey steam rather heavily, maybe 2-3 times as much as one would expect. Made me think I had a cracked head, but does not look likely. It no longer steams/smokes any more than any other vehicle. _20190213_094404.jpegDSC_2254.jpegDSC_2258.jpegDSC_2259.jpegDSC_2256.jpeg

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Im not 100% behind your reasoning for running it backwards since it should be baffled to function in one direction anyway.
 

RonD

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Yes, a catch can do what you describe on older engines

First, where does the oil vapor in the engine(crankcase and valve covers) come from?

Motor oil vapor point is 450degF

So not from bearings or valve train, they would fail at those temps, they spray oil out as a hot liquid not a vapor


Oil vapor comes from Blow-by
When a cylinder fires some of the 1,200+ degree gases "blow-by" the piston and rings
The cylinder walls and pistons are coated in oil............................
So that's where the oil vapor in the crankcase and valve covers comes from, blow-by vaporizes some of the oil coating

As an engine gets older blow-by increases, just normal wear and tear on rings
So there is more oil vapor to deal with
And you will get what you describe.

The PCV system has a baffle under the PCV valve to try and condense the oil vapor and the Breather hose, vent hose, on the other valve cover should be letting in cooler outside air to help condense the oil vapor back to liquid oil at the top of the engine.

But when oil vapor gets to be too much then PCV system is overwhelmed.
So catch can can be used, its a method of condensing the oil vapor back to a liquid before its sucked into the intake.

The extra oil vapor in the intake will cause lean mix Pinging/Knocking under load

It shouldn't have caused a higher idle, could be the PCV system was allowing extra air in somewhere


EDIT:

Get a 4.0l, lol, couldn't resist, :)
 
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PetroleumJunkie412

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Im not 100% behind your reasoning for running it backwards since it should be baffled to function in one direction anyway.
On a better unit, I'd absolutely agree with you. This one is not baffled, though. What they call a baffle is two screw together cheese grater style discs, which I popped a filter between.

Good point.

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PetroleumJunkie412

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The extra oil vapor in the intake will cause lean mix Pinging/Knocking under load

It shouldn't have caused a higher idle, could be the PCV system was allowing extra air in somewhere
On point! Motor has 170,000 miles on it (may be 270,000; I know it has made the trip between Pittsburgh and Washington state at least three times).

And I'm guessing that is the case with an air leak. Still waiting on the new pcv grommets to get here. Mine are very worn.

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On a better unit, I'd absolutely agree with you. This one is not baffled, though. What they call a baffle is two screw together cheese grater style discs, which I popped a filter between.

Good point.

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Fair enough, I was just curious. I installed one on my 2.3 Dohc a few weeks ago. Mine came with a pretty decent baffle setup but I did the same SS scrubber trick though.
 

PetroleumJunkie412

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Fair enough, I was just curious. I installed one on my 2.3 Dohc a few weeks ago. Mine came with a pretty decent baffle setup but I did the same SS scrubber trick though.
I wish I could have found an aluminum one before I shoved a stainless one in there. The thought of one if those stainless ribbons getting pulled through the engine scares the crap out of me.

Thought about using a copper one, but didn't want to find out the hard way if crank case gasses would react poorly with it, and send some sort of gaseous death into my intake.

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There's not a massive amount of flow going through the can so I highly doubt you'd ever have issues with any shards coming out. Its very common to do this and I haven't herd of any issues yet. I use the same stainless scrubbers in the condensor on my moonshine still that makes way more pressure. Never drank any stainless steel yet! :icon_rofl:

Im with you on the copper though. Copper can oxidize and that vapor is full of all sorts of nasty stuff. Same with aluminum, safer just to stick with SS.
 

PetroleumJunkie412

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RonD

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And just as a heads up, Catch Cans work best in cooler places in the engine bay, you are trying to condense the oil vapor, i.e. cooling it so it becomes a liquid and just leaves the blow-by gases/exhaust gases to be sucked into the intake.

We used to stick steel wool in these cans to increase surface area for condensation which helps as well
 
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PetroleumJunkie412

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200 miles later...DSC_2264.jpeg

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Dirtman

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Drink that!
 


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