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When you do a compression test all spark plugs must be removed so you get good cranking speed
Battery voltage should be 12.4v to 12.8volts, for the same reason
Press gas pedal to the floor and hold it down when cranking, this is to get good air flow into the engine
And yes, longer crank time, 10 to 12 seconds, you need to "hear" 5 to 7 "hits" of the compression stroke from the cylinder being tested, you will hear it
Expected compression on the 2.9l is 150psi, at sea level and new, lol
In Idaho with the higher elevation compression will be lower
And with higher miles it will be lower but I would expect 135-145psi
On each intake valve there is a valve guide seal inside the valve spring in the valve cover area
Vacuum in the intake manifold is about 18" of negative pressure, this will cause oil to be sucked in from intake valves valve stem if the seal is worn out
The oil is then sucked in to the cylinder when valve opens
This is the most common way oil gets into cylinders
The PCV Valve combats this oil being sucked in, so it needs to be in good working order
PCV Valve should be changed every 3 oil changes, and its hose cleaned out, also the Breather hose
PCV Valve creates negative pressure in the valve cover area which means less oil would be pulled down the intake valve stems
On older engines like the 2.9l, people often install a Catch Can on the PCV Valve hose, this reduces the amount of Blow-by oil vapor being sucked into the engine
On all piston engines, new or old, each time a cylinder fires some of the HOT gases will "blow by" the piston and rings and into the crank case
As any engine ages the amount of blow-by increases, this is normal
The HOT blow-by will vaporize some of the oil on cylinder walls and piston sides, this is the ONLY place in the engine that can create oil vapor, bearings and valve train never get hot enough to vaporize oil
Most of the oil vapor stays in the crank case area but it is hot so some of it "rises" thru the drain holes in the head and into the valve cover areas
This oil vapor is then sucked in thru the PCV Valve and into the intake and then into the cylinders
A Catch Can is used to try and cool down the oil vapor so it condenses in the can, so it is not sucked into the intake
Using a higher grade oil can also reduce the oil vapor in the engine, it doesn't vaporize as much as lower grade oil
Burning oil is not great for the spark plugs or the exhaust system, lol, I know DUH
So you may just need to clean them more often and check out and refresh PCV system
To test if Valve guide seals are leaking, and AFTER new PCV Valve
After engine is warmed up, coast down a hill IN GEAR, this creates a HIGH Vacuum in the intake
At the bottom of the hill press down on gas pedal(still in gear) and watch tail pipe emissions
If you see a puff of smoke valve guide seal are leaking, the bigger the PUFF the bigger the leaks