How to change the PCV Valve on a Mazda 6 with a 3.0L from 2004 to 2008. You may be wanting to do a thorough maintenance on your Mazda 3.0L and found the PCV Valve isn’t in plain sight. Not to worry, this quick and short article will go over where to find it and how to replace it.
Most people don’t realize how crucial a PCV Valve is. When they stop functioning like the should be, problems can arise. Your car can start using oil and burn it out the tail-pipe, or start blowing gaskets. The PCV Valve balances the crankcase pressure while the pistons are in motion.
Without this valve, the crankcase can build up pressure and cause your gaskets to start leaking. On the other hand, with the valve in the stuck open position, will make your engine to suck oil into the intake and burn oil.
How the PCV Valve on a Mazda 6 3.0L Works
I have mentioned what can happen if it isn’t working properly. However, it can be helpful to know what it does. PCV stand for “Positive Crankcase Ventilation.”
The PCV valve system operates on a straightforward principle. It regulates the pressure in the crankcase. Connected to the intake, it modulates vacuum levels. When the engine is at idle, the vacuum is high. With the high vacuum, the check valve restricts vacuum from being pulled on the crankcase.
As the RPM increases and vacuum drops, the valve opens wider, permitting more pressure into the intake. This pressure and gases then re-enter the combustion cycle, burning off alongside fresh fuel and air. This prevents condensation in the oil, and keeps gaskets from leaking due to pressure.
So, basically, when the engine is at idle or low RPM, the crankcase isn’t under that much pressure. When you increase the RPM’s, the crankcase starts to build pressure. The regulated vacuum, releases that pressure and allow the engine to burn off the excess pressure.
Do not think that a PCV Valve is only for emissions, there are many articles that make that statement. California required this Valve in 1961. Car engines up till then, just vented the oil vapor straight to the atmosphere. By venting straight into the air, you had some pollutants, but you also had oil usage.
The PCV valve just allows the oil vapor to go back into the combustion chamber to be burned. This reduces the number of pollutants released by the engine. However, the PCV also reduces how much oil an engine loses. Learn more about how a PCV valve works reading my article: How Does a PCV Valve Work.
What to Look for With a Bad PCV Valve on a Mazda 6
Most of the time, when a PCV Valve goes bad, the driver doesn’t even notice while driving. What you may notice, is oil puddles under the car, or the car smoking out the exhaust.
It can affect the car’s performance in some instances, but normally not. Depending on the engine, sometimes, although rarely. A defective PCV Valve can cause the engine to misfire, or stumble upon acceleration.
What To Look For If Valve Is Stuck Closed
- Whistling or hissing sound coming from the engine
- Oil leaks, most commonly from the valve cover gasket
- A decrease in your fuel mileage
- Possible “Check Engine Light”. This would be set off if your emission levels are far enough off.
What To Look For If Valve Is Stuck Open
- Excessive oil residual build up around the PCV Valve hose or around the valve cover
- Rough idle or even misfiring, rare possibility in noticing a drop in performance
- Harder to start after the car has sat for a period of time
- Blue, gray or white smoke coming from exhaust pipe, meaning it is burning oil
Locating Your PCV Valve on Your Mazda 6 3.0L
You will find at the very back of the engine, a hose that curves downward. This hose is the PCV Valve hose and the valve is down and below the plenum. You will be removing the hose from the plenum and from the valve itself.
There is a bracket that mounts a module and a wire retainer, remove this with two bolts . This will give you room to move your hand around. Disconnect the small bolts to the module and bracket, and peel them back out of the way. No need to disconnect wires or hoses from this.
Remove the PVC Hose by releasing the clamp and pulling it back. Pull the hose from the plenum and then pull it off the PCV Valve. There is a smaller hose also going to the plenum for you to remove. Looking at the where the PCV Hose goes to the plenum, this next hose is to the right and a little below it. Again, pull and slide the clamp back and pull this hose back and push it out of the way.
You will now have a clear view of the PCV Valve. Using a long pair of needle nose pliers. Grab a hold of the square part of the valve and twist it counter clockwise, while pulling lightly upward.
Using the same pliers, take the new valve and put it back into the hole and twist it clockwise. This all could possibly be done by hand. So, you can try it first with you hand first.
Now reconnect the PCV Hose, then the smaller hose. Put the bracket back to the firewall and you have successfully change a PCV Valve on a Mazda 6 3.0L
Video How to Change the PCV Valve on a Mazda 6: 3.0L 04 to 08
Shop Amazon for parts related to replacing the PCV valve on a Mazda 6.
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