Question about 2005 Mazda 6

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Excessive pressure in the crankcase of a mazda 2005 6

Excessive pressure in the crankcase. have already replaced the pcv valve. still no good

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Have you checked the hose from the valve cover to the air cleaner ?
The PCV valve pulls air from the crankcase into the intake, but the crankcase has to get fresh air from the air cleaner too.
If the crankcase is getting extra pressure from the cylinders you should have a check engine light and trouble codes.

Posted on Jan 15, 2013


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SOURCE: How to replace PCV Valve

Step 1: Identify PCV and remove connectors for space:
If you look at the back of the engine, there is a 5/8" tube running into the intake manifold. In picture #1, you'll see that this tube has a green sticker on it (red box #3). You can't see the PCV valve from this angle, but if you follow that tube down, you'll see a gray plastic piece. That is the PCV valve.

For step 1, we remove the 2 hoses and an electrical connectors (red boxes 1, 2, and 3). That will give us more clearance.

wol_error.gifThis image has been resized. Click this bar to view the full image.pcv_01.jpg

Step 2: Remove the tubes to get to the PCV valves.
Right, now you need to remove the 5/8" tube completely (the one with the green sticker). Picture #2 you can see that there are some hose-grips on that tubes, so using small pliers will help here.

wol_error.gifThis image has been resized. Click this bar to view the full image.pcv_02.jpg

After that, there is another adapter connected to that piece. Please see picture #3 and #4 for reference. That adapter must be remove because it spins freely. To remove, use your hand (no tools needed). Press the green adapter to release the grip and pull up.

wol_error.gifThis image has been resized. Click this bar to view the full image.pcv_03.jpg

wol_error.gifThis image has been resized. Click this bar to view the full image.pcv_04.jpg

Step 3: Remove PCV valve
You can see the full assembly in picture #3 and #4. Next is to remove the PCV valve. There is a shallow thread on that PCV valve, so you'll need to turn it to remove it. Use something to help you, like a clamp or pliers and rotate the PCV valve 1/4 turn counter-clockwise. This will be kind of difficult, but just keep working on it and it will loosen and pop out. A long reach nose-pliers can come in handy. In picture #5, you can see how tight it is down there.

wol_error.gifThis image has been resized. Click this bar to view the full image.pcv_05.jpg

Step 4: Replace and reconnect.
Replace the old PCV valve with the new one. Reconnect all the other hoses and connectors. Start engine and check for leaks. That's it.

hope this helps good luck!

Posted on Sep 07, 2011

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Does a 2005 Pontiac Sunfire have a PCV valve?

Crankcase Ventilation System Description
A crankcase ventilation system is used to consume crankcase vapors in the combustion process instead of venting them to atmosphere. Fresh air from the intake system is supplied to the crankcase, mixed with blow by gases and then passed through a calibrated orifice into the intake manifold.
The primary control is through the positive crankcase ventilation (PCV) orifice which meters the flow at a rate depending on inlet vacuum. The PCV orifice is an integral part of the camshaft cover. If abnormal operating conditions occur, the system is designed to allow excessive amounts of blow by gases to back flow through the crankcase vent into the intake system to be consumed by normal combustion.

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PCV - Positive Crankcase Ventilation valve/pipe

1.8) PCV - Positive Crankcase Ventilation valve

What is it? The PCV valve is a thumb sizedplastic elbow that is designed to relieve the build up of pressure in the crankcase. A pipe connects the PCV to the airducting. The function of the PCV is toreturn exhaust gases (blow-by of the piston rings during ignition) from thecrank case to the air intake.

Where is it located? PCV is found on the crankcasebreather pipe or cam cover

How does it work? Some pressure relief systems have a convoluted set of internalpassageways within the crankcase to allow oil mist to settle out and to allow excess pressure tovent in an unrestricted manner through a pipe directly into the air ducting. On other systems thePCV opens when the vacuum in the inlet manifold is low i.e. when the engine isrunning at speed and when the positive pressure of blow-by gases builds up inthe crank case. The PCV is held closefor the most part by the vacuum of the inlet manifold at idle. Often the PCV is unidirectional, allowing gas/airto flow only from the crankcase to the throttle intake. If the valve becomes clogged and stays closedthis can cause pressure buildup in the crankcase and this in turn causes oil toleak through seals etc. Alternatively ifthe valve stays open the ingress of unmetered air can upset thefuel/mix and cause rough idling.

Symptoms of faulty PCV

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How to check? Remove the PCV and first give is ashake, if it rattles freely this is a good sign. No rattle could indicate a gummed upvalve. **** and blow though it, one way should be easy the other way difficult. If the type of PCV is governed by a vacuumline then the passage of air through the valve will be restricted until asuitable vacuum is applied to it.

How to fix? It may be possible to repair the PCV by rinsing it out with a little fuel or carburetor choke spray to act as a solvent on the oily gunk that has gummed it up. If the valve is beyond reasonable repair then replace it.

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the PCV system draws crankcase fumes into the intake at idle and lower throttle situations. air going into the crankcase is filtered by the small PCV filter, where the oil shows up....

At highter throttle and lower intake manifold pressures, the system reverses, the PCV valve closes, and the fumes exit the crankcase VIA the breather filter. All of this is normal.

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