This CRP is specifically for the Mazda 6s (V6) platform.
The PCV (Positive Crankcase Ventilation) Valve is a check valve that allows excess exhaust fumes in the crank case to re-enter the intake manifold and be re-combusted for emissions sake.
If the valve breaks (its basically plastic), one of two things can happen,
The valve gets stuck close. Pressure builds up in the crankcase, eventually finding an outlet. This usually results in oil spraying back up into the intake tract, or blowing the dipstick out of its holder.
The valve gets stuck open. When vaccuum is applied (application of throttle), the intake air sucks the oil out of the crankcase using the pcv hose as a large straw.
If option 2 occurs, a low oil condition can occur, which has an extremely high likelyhood of spinning a bearing. This can result in just a rod bearing replacement, or a complete bottom end rebuild. ($$$ and Very Bad)
Identifying The Problem:
Weekly oil checks will reveal a sudden increase in oil consumption. Sometimes blue smoke exiting the exhaust can be indicative of oil being sucked into the intake tract of the engine (and being burned in the combustion chamber).
There is no "concrete" solution at this time. The only thing that can be done is preventative maintance.
Check your oil level at least bi-weekly or weekly. It only takes a few seconds. Pop the hood before leaving in the morning (weekends are great for this) and just check the dipstick. Oil level should be between the top 0 and the ford logo on the dipstick.
Inspect the PCV valve every oil change (5-7.5k miles). Below is instructions on how to do so. Easiest method would be removing the hose from the rear of the manifold, and applying pressure/vaccuum to test for resistance.
Purchase a second PCV valve and run it in-line with the current valve (on the same hose). This will provide a level of redundancy. If one of the valves should fail, the car will still be ok.
PCV VALVE INSPECTION [AJ]
Removing the PCV valve might damage to the tab of the PCV valve and it will not be able to be reinstalled. Due to this, inspect the PCV valve with it installed on the vehicle.
1. Disconnect the negative battery cable.
2. Disconnect the PCV hose from the PCV valve.
3. Apply pressure to the PCV valve and verify that there is no airflow.
If there is airflow, replace the PCV valve.
4. Apply vacuum to the PCV valve and verify that there is airflow.
If there is no airflow, replace the PCV valve.
#1 is the valve for anyone wondering.
Replacement valves are available from forum sponsors and online mazda parts sites for around 10-12 dollars.