Re: 4.7 Burning Oil, No Suction from PCV Valve?
If you want to be sure that the PCV line is open, just disconnect the hose from the PCV valve and start the engine. It will run at a higher idle, but thats no problem. Feel with your finger if you have vacuum at the line, it should be strong. If not, there is some blockage in the line towards the inlet duct. Also not sure if a not properly working PCV system would increase the oil consumption (could be if PCV valve was sticking open), but at least it can cause sludge and other buildup due to the blowby gasses which canīt go anywhere in the block and will mix with the oil.
My 4.7 was burning oil as well and i also changed the PCV valve. No cure. Finally changed all the valve stem seals (hell of a job with engine in place) and the problem was solved. Take care in using thicker oils and additives. It could slow down oil consumption, but it can also lower the pressure/flow at the bearings (more pressure losses in the canals due to the higher viscosity) and compromise the lubrication.
JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
Monroe Reflex shocks /
Pirelli Scorpion ATR 245/65/17/
Transgo reprogramming shiftkit.