Hey everyone I'm new here and new to LS motors. I have a 2004 Chevy Silverado 2500 with the 6.0 gasser. I bought the truck with a few modifications already on it. The issue I'm having is with the aftermarket valve covers and catch can. The individual before me put them on but the aftermarket valve cover doesn't have a pcv valve and thus is causing my catch can to fill up so fast that I can't keep up with it and then causes to much bleed by and obviously causes a bunch of smoke to come out of my exhaust. I've looked and can't seem to find any "aftermarket" pcv valves that will work so I don't have to spend the money on new OE ones that have the updated channel in the bottom of the valve cover. Any suggestions?

 

Are the valve covers stamped or marked with the manufacturer name? If so, have you tried contacting them to see if they have a PCV valve that will work?

It’s also possible to run without a PCV valve by installing an orifice into the tubing. I don’t know what size it would have to be so you’d probably need to do some trial and error to get it right. Inline 6 Jeep engines are set up that way and the orifice on them is about 1/16” diameter.

You can tell it’s right by reading vacuum at the engine oil dipstick tube (at operating temperature). The orifice is correct when you have less than 2 in-Hg vacuum at the tube.

 

Is that the new Jeep 4.0 liter motor?. On my old 1970's 258 inline 6 cylinder cubic inch CJ-5 motor,(4.22 liters) it had the standard PCV valve on the valve cover.If it needed changing, you just inspected the seal, and chucked the PCV valve in the trash-bin. If the seal was hard, you chucked it out as well.

Back then AMC owned the Jeep brand, not Chrysler/Fiat, so after all these years it's likely changed, no doubt, and is more complicated, then before.

 

I can’t say for sure what year it started, but I’ve worked on 3 wranglers with the 4.0 that used an orifice instead of a valve - one 1998 and (2) 2005.

There’s not really anything more complicated about it. The PCV system operation works the same and the orifice allows for metered return of blow-by gases into the intake, as well as prevents backfires into the intake, just like a valve would. GM is currently using an orifice on their 4 cylinder ecotec engines, located in the intake manifold between the #2 & #3 intake ports.

That said, based on what I’ve seen from the Jeep 4.0 and the GM ecotec’s, a valve is better than an orifice just because it’s less prone to plugging. GM has been having several problems with the PCV systems plugging up and causing more problems than just leaks.

 

Yeah, too much pressure in the engine could blow out gaskets and seals. Can you adapt something to replace it or modify it so that it won't plug up?

 

I don’t know what could be done to prevent them from plugging, but replacing it with a valve is definitely possible as long as you adapt the fittings/grommets correctly. The valve itself doesn’t have to be mounted in the valve cover and could be installed in the hose/tubing between the VC and intake.

The primary thing to address is that it has the correct flow rate. As stated before, this can be verified by checking vacuum at the engine oil dipstick tube - a maximum of 2” vacuum at idle is acceptable, but ideally it’s at or just below 1” - the idea is there’s just enough vacuum in the crankcase to keep the blow-by gases flowing towards the intake when engine vacuum is at its max.

 

Sounds like you know more about the PCV system then I do. I was just reading that the first PVC systems came out during WW II. What happened was the downdraft tube that all vehicles like my father's old I-6 inline 1948 Studebaker, which still had the downdraft tube (about an inch or so wide, putting out oil fumes into the atmosphere) was that when our soldiers went through deep water crossings, the engines would get lots of water in the oil leading to engine failure.

So the armed forces brass came up with the first system that fed the oil fumes back into the motors or into the air-cleaners. IOW, a PVC system, but not because of air pollution. Sure wish my dad kept that old car. It had a hill-holder clutch and an overdrive, activated by pulling out a T-handle under the dash. The OD was like a transfer case, mounted behind the 3-Speed transmission, not part of it at all.