The LS versions of motors have been notorious for consuming vast amounts of oil. As a Texan I think I am supposed to promote this as a good and natural thing. As a guy who just bought 5L of oil for $37 because the 1L I needed cost $11. I am looking for ways to cut cost, not to mention make the vehicle run better. The University of YouTube in unanimous in its disparaging of the Positive Crankcase Ventilation system on this engine. The earliest versions had what used to be common place. A small replaceable valve with a weighted plate and a spring. Once the pressure in the crank case got high enough it would defeat the spring opening the valve and letting the pressurized fumes from the crankcase flow back into the intake manifold so that any contaminates would be burned in the combustion chamber and not just vented into the natural environment.
This is a nifty idea, when it works. Due to “insert stupid reason here” GM replaced this valve with an “orifice” basically a tube that tapers down to a small opening and then opens back up. Not sure what the engineering decision was behind this. Possibly the quick contraction and expansion on vapors might turn them back into liquid or something like that. The main idea is to keep as much oil vapor inside the engine and allow it to condensate back into oil that can lubricate the engine. It didn’t work. Specifically the drivers side valve cover that houses this tube was built with a oil baffle that was supposed to deflect the oil that is being pumped up by the lifters through the push rods and used to lubricate the valve train. The baffle basically sits over the rocker arms dripping oil back down onto them while it is being showered with oil by the push rods. This spraying, dripping and oil throwing within the engine causes smaller droplets of the hot oil to become a vapor. The baffle is supposed to slow down the vapor on its way to the PCV orifice and allow it to drain back off its walls into the engine.
Sadly with this design it doesn’t. The drip hole get clogged rather quickly and the hole that allows the vapor in is actually located above on of the rocker arms and oil gets shot directly into the baffle. The way to fix it is either to drill a bunch of drain holes at the bottom of the baffle all the way along or get the updated one which moves the intake hole to a position between two rocker. This new hole also has a couple of splash guards.
To replace it, I disconnect the battery, pull the engine cover, move the main wiring harness over, and remove the coil packs. I take the time to remove the alternator main wire as it has been incorrectly re-attached at some point and is laying across the engine. Nothing seems to corroded and all the fasteners come free without much of a fight. I swap over the pcv hose, install the 4 main bolts and the gasket on the new valve cover and put it all back together, making sure to torque the new bolts to 112 inch lbs.
The finished job is done and I will be giving it a test drive this afternoon. It is a simple fix and I really wonder if this will take care of all the issues I have been seeing. If it fixes the misfire I will be amazed.
