Hose connecting valve cover

Chris97K1500 · July 23, 2004

What is the purpose of this hose? It goes from the valve cover on the passenger side of my 5.7 to the air intake tube just before going into the TB. Is it some sort of gas recirculating device? I figured it would add heat to the air going into the engine, which is not what you want. I was thinking about just putting a breather filter on the outlet on the valve cover and plugging up the hole in the air intake tube. Any ideas? Chris

blue2kzr2 · July 24, 2004

PCV inlet. It actually takes air FROM the intake and pulls it into the crankcase. There should be a similar spot on the other side, with a tube going to the TB.

Chris97K1500 · July 24, 2004

okay that makes sense. What's the purpose for this? Why not just have 2 little filter breathers on there? Emissions? Just doesn't make sense you would want to circulate hot air back into the engine. Chris

blue2kzr2 · July 24, 2004

Removes compustion gasses from the crankcase. It introduces them into the intake air to re-burn them with the intake charge. Lowr emissions, longer oil life, lower pressure in the crankcase.

Here's what my GM service manual says about the PCV system on the 2000 4.3 L engine. I imagine it's a similar description for yours.

"A crankcase ventilation system is used in order to provide a more complete scavenging of crankcase vapors. The air cleaner supplies fresh air through a filter to the crankcase. The crankcase mixes the fresh air with blow-by gases. This mixture then passes through a crankcase ventilation valve into the intake manifold.

The primary control is through the crankcase ventilation valve (1), which meters the flow at a rate depending on the manifold vacuum.

In order to maintain an idle quality, the crankcase ventilation valve restricts the flow when the intake manifold vacuum is high. If abnormal operating conditions arise, the system is designed in order to allow the excessive amounts of blow-by gases to back flow through the crankcase vent tube into the air cleaner in order to be consumed by normal combustion."

Chris97K1500 · July 24, 2004

Thanks, I guess I'll just leave it be. I'm going to be working on a "homemade" CAI this week on my truck. I'm relocating the battery to the other side of the truck and I should have plenty of room to work with. I just thought about doing something with this hose, guess I won't. Thanks, again, Chris