Finally Jumped on the Oil Catch Can Bandwagon

[Jason in DLH]

Hi @iamdub
Is this something I should do for my 97 5.7 vortec?
I everyone's pics to do with the catch can I cannot see where it comes from. Is it rocker cover to to inlet?
I want to delete the egr at some stage,does it have anything to do with that?
Cheers

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The catch can connects to the PCV valve. Here’s good instructions from the JLT product I used...

https://www.jlttruecoldair.com/content/3084D.pdf

The EGR is different as that recirculates the exhaust to lessen emissions. The catch can is to “catch” oil droplets, unburnt fuel, and condensation from the Crankcase ventilation.

 

[97YukonNZ]

The catch can connects to the PCV valve. Here’s good instructions from the JLT product I used...

https://www.jlttruecoldair.com/content/3084D.pdf

The EGR is different as that recirculates the exhaust to lessen emissions. The catch can is to “catch” oil droplets, unburnt fuel, and condensation from the Crankcase ventilation.

Hi Jason [emoji106]
Will look into that and see what I can get in the way of a catch can from 1 of our motor stores. Failing that Ebay or I will make 1.
Yes,I know how the e.g.r works from exhaust to inlet for emissions. I've seen how much sludge builds up in a diesel manifold and am keen to clean the inlet up.

Thanks for the info [emoji111]

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[George B]

Yup. The temperature swing from the engine cooling after a drive produces condensation inside the engine in addition to the moisture created as a byproduct of combustion. Short drives produce moisture but aren't long enough to burn it off, so it collects in the oil in the pan. When the engine does get hot, the oily water is the first to steam off in the PCV system so it fills the catch can. In the meantime, you're pumping oil polluted and thinned by water through your engine.

Yup. My wife is short tripping out envoy to death. Only goes on short trips in town. I need to drive that thing weekly to burn it off. The 4..2L I6 has a passive vent from the valve cover to the air intake ahead of the TB so it gunks the TB up terrible. I need to devise a catch can or something for that. I don't think that truck has a true PCV in a sense. I thought about adding one somehow but I also thought about just venting to atmosphere with the crankcase.

 

[97YukonNZ]

Yup. My wife is short tripping out envoy to death. Only goes on short trips in town. I need to drive that thing weekly to burn it off. The 4..2L I6 has a passive vent from the valve cover to the air intake ahead of the TB so it gunks the TB up terrible. I need to devise a catch can or something for that. I don't think that truck has a true PCV in a sense. I thought about adding one somehow but I also thought about just venting to atmosphere with the crankcase.

Yes,after looking at my 5.7 last night I have the same setup with a breather to the intake before the t.b. thinking I should catch can that as well. Took my t.b off a while ago to grind the restrictor plate off and it looked pretty good!

Definitely doing catch can on drivers side now after reading about it. Will have a look at t.b to see if any build up from last inspection.

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[iamdub]

Yup. My wife is short tripping out envoy to death. Only goes on short trips in town. I need to drive that thing weekly to burn it off. The 4..2L I6 has a passive vent from the valve cover to the air intake ahead of the TB so it gunks the TB up terrible. I need to devise a catch can or something for that. I don't think that truck has a true PCV in a sense. I thought about adding one somehow but I also thought about just venting to atmosphere with the crankcase.

I'm not familiar with the flow of air into and out of the crankcase on that engine. You can't vent an LS or it'll throw codes. You can probably tune them out, though. But, I'd rather keep it functional since the strong vacuum helps to vacate the crankcase instead of letting the pistons pump it out.

If that one on the passenger side is a vent OUT of the valve cover and IN to the air intake tube, I'd cap off that valve cover with a breather tube. If it gets oily, then reconnect it to the intake tube but with a catch can to filter the oil.

 

[George B]

I'm not familiar with the flow of air into and out of the crankcase on that engine. You can't vent an LS or it'll throw codes. You can probably tune them out, though. But, I'd rather keep it functional since the strong vacuum helps to vacate the crankcase instead of letting the pistons pump it out.

If that one on the passenger side is a vent OUT of the valve cover and IN to the air intake tube, I'd cap off that valve cover with a breather tube. If it gets oily, then reconnect it to the intake tube but with a catch can to filter the oil.

The way I understand it the “pcv” is part of a port in the intake that links up with the block. It is supposed to make up fresh air through the air inlet tube but this truck has bad enough blow by now that it tends to send it’s oily air into the intake tube at times. It pools in the plenum ahead of the throttle body. I have to search again for where I read the description of the system.

Edit: went out and looked at it again. I can find the hose that goes to the block from the intake. That hose is rock hard and I hate to mess with it now and risk breaking the plastic barb on the intake. I will need to clean the TB this spring and can get to that port inside the intake behind the TB. I will flow some seafoam down it followed by some carb clean before an oil change. Then try to purge it with some air.

 

[iamdub]

Hi @iamdub
Is this something I should do for my 97 5.7 vortec?
I everyone's pics to do with the catch can I cannot see where it comes from. Is it rocker cover to to inlet?
I want to delete the egr at some stage,does it have anything to do with that?
Cheers [emoji111]

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The PCV setup on the Vortec is quite different from that of the LS engine. On the LS, it flows from the driver side rocker cover to the top center of the intake manifold. It's been a while, but I think the Vortec just has a PCV valve and tube from the rocker cover to the intake duct. I'd put a breather filter on the rocker cover and cap off the port on the intake tube.

You can delete EGR, but it'll throw codes unless you can tune them out. I recall the thing to do was to reduce the size of the EGR orifice. There were reducers made to go under the EGR valve. I actually have one with gaskets that was never used. I'd send it to you if you were in the 'States (or is it really such a pain to ship to NZ?). You could probably make one if you're handy with basic metalworking tools. It's just like the block-off plate (link below), but with a hole in it and longer screws so the EGR valve can be installed on top of it. Supposedly, they figured out the size the hole needs to be to minimize the flow of exhaust gasses but keep the PCM happy.

https://www.egrperformance.com/prod...-chevy-silverado-surburban-4-3-5-7-cpi-vortec

 

[97YukonNZ]

The PCV setup on the Vortec is quite different from that of the LS engine. On the LS, it flows from the driver side rocker cover to the top center of the intake manifold. It's been a while, but I think the Vortec just has a PCV valve and tube from the rocker cover to the intake duct. I'd put a breather filter on the rocker cover and cap off the port on the intake tube.

You can delete EGR, but it'll throw codes unless you can tune them out. I recall the thing to do was to reduce the size of the EGR orifice. There were reducers made to go under the EGR valve. I actually have one with gaskets that was never used. I'd send it to you if you were in the 'States (or is it really such a pain to ship to NZ?). You could probably make one if you're handy with basic metalworking tools. It's just like the block-off plate (link below), but with a hole in it and longer screws so the EGR valve can be installed on top of it. Supposedly, they figured out the size the hole needs to be to minimize the flow of exhaust gasses but keep the PCM happy.

https://www.egrperformance.com/prod...-chevy-silverado-surburban-4-3-5-7-cpi-vortec

Thanks for this info. [emoji111]
Is helping me understand the subtleties of doing these wee jobs to help the longevity of the motor.
What's say I organize a catch can with an air breather on top away from the rocker cover and cap the hose close to the intake?
If I put a breather directly on the rocker it will have the propensity to leave an oily residue around the area.
I dont need to worry about the rocker cover to intake after the maf and before the t.b?
When you get the chance could you take a photo of the restrictor kit you have please.
If it would be an advantage to use that instead of blocking off completely and throwing codes until tuned.
Would probably fit in a mailing envelope?
Cheers Tony

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[iamdub]

Thanks for this info. [emoji111]
Is helping me understand the subtleties of doing these wee jobs to help the longevity of the motor.
What's say I organize a catch can with an air breather on top away from the rocker cover and cap the hose close to the intake?
If I put a breather directly on the rocker it will have the propensity to leave an oily residue around the area.
I dont need to worry about the rocker cover to intake after the maf and before the t.b?
When you get the chance could you take a photo of the restrictor kit you have please.
If it would be an advantage to use that instead of blocking off completely and throwing codes until tuned.
Would probably fit in a mailing envelope?
Cheers Tony

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I like the remote catch can with a breather on it. They're cheap on ebay and Amazon.

I'm sure the rocker cover to intake tube can be done the same. You're gonna have to double check these circuits and how they flow. I'm trying to think waaay back on my '02 4.3. I think it had a tube from the driver cover to the intake tube, then another from the passenger cover to the back of the throttle body "hat". The passenger side is the one I put a breather on and capped off the port on the back of the hat. I can't remember what I did with the one on the driver side. I don't think it's like an LS. On an LS, the passenger side is air INTO the engine, driver side is PCV OUT of the engine and into the intake manifold. On the Vortec, they're both out of the covers and into the intake tract after the MAF and before the TB.

...Maybe get a dual inlet catch can? They have them with and without the breather filter. My guess is that you shouldn't have a breather filter if it's connected to the intake. So, if you have a hose from each cover going to the two inlets on the catch can, you'd either have the breather filter and the outlet of the can plugged off or you have the breather plugged off and the outlet of the can connected to the intake. I say get the one with the breather filter so you'll have the option either way.

Gimme a few minutes and I'll go snap a pic of the restrictor kit. It'd definitely fit in a small envelope.

 

[iamdub]

@97YukonNZ, I forgot to post a link to the catch can I was looking at:

https://www.amazon.com/Sporacingrts...n+breather&qid=1616550925&s=automotive&sr=1-6