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This CRP is specifically for the Mazda 6s (V6) platform.

PCV
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.


Problem:
If the valve breaks (its basically plastic), one of two things can happen,
http://forum.mazda6tech.com/viewtopic.php?p=36503#36503

1: 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.

2: 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.


Problem 2:
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).


Solutions:
There is no "concrete" solution at this time. The only thing that can be done is preventative maintance.

1. 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.

2. 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.

3/ 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]



NOTE:
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.
 

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Originally posted by Toadster@Nov 22 2005, 10:03 PM
that valve is a real PITA to get to eh?
[snapback]563101[/snapback]​
Not really, visible by peering off to the driver's side shoulder of the upper intake manifold. Taking off the upper intake will make it a piece of cake if you can't get to it as is for some reason.
 

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Originally posted by mmarfan@Nov 21 2005, 01:19 PM
Yea I'm ALWAYS 1 quart low every oil change... I'm at 32000 miles... can I get a new motor out of this... :D
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Not unless your engine fails... and for those after their warranties it would be a VERY good idea to constantly keep an eye on this.
 

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Originally posted by Mazda_Gremlyn@Nov 22 2005, 10:16 PM
Not unless your engine fails... and for those after their warranties it would be a VERY good idea to constantly keep an eye on this.
[snapback]563108[/snapback]​
Or not, then it becomes a really good idea to buy a Duratec 3.5L :drool:
 

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That has to be it, that HAS to be the reason for my engine troubles, The oil was alwasy low and i was always adding a quart and a half, and i have experienced the problem when they replaced it the last time, this is very interesting, a cheap replacement part is most likley the cause of the 2 engines i went through in a matter of months. how would you run a second valve in line with the first?
 

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how would you run a second valve in line with the first?
[/b]
Click the link in the post just above your own.
 

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I don't know...maybe I'm reading the guide wrong or something. But I really don't seem to understand.

This is to REPLACE the factor PCV valve? Cuz later in the thread Fordman says that the factory one is still there...

Also, there are 2 parts of the write up that state to insert the threaded end into something, but the new valve only has one threaded end...

Gonna go out and take a look at my 6, hopefully it helps me understand what you're all talking about.

[edit] - Updated with some pictures of my '05 6s, which doesn't appear to have the same valve. Wonder if I should still change it out? It feels like soft plastic/rubber. Not sure how durable it is...

From the front (zoomed):


From the driver's side (zoomed):


From the top:
 

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My guide adds a second PCV valve in between the intake manifold and the factory PCV valve. Yes only one end of the Purolator PCV valve is threaded, thought it would be easier to describe it as that since the PCV valve has to go in-line a certain way, otherwise it is not doing anything and still allows oil into the intake.
 

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Right.
 

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I need some serious help here guys... brought my car in to dealer due to a loud tapping from engine... got a call and they tell me not a drop of oil in engine.... very odd... I personally changed oil like 1000 miles ago... no leaks... and added 5 quarts... I also read somewhere else that there was other causes... gonna do some searching but anyone else have any more inut that would be greatly appreciated

Nick
 

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I need some serious help here guys... brought my car in to dealer due to a loud tapping from engine... got a call and they tell me not a drop of oil in engine.... very odd... I personally changed oil like 1000 miles ago... no leaks... and added 5 quarts... I also read somewhere else that there was other causes... gonna do some searching but anyone else have any more inut that would be greatly appreciated

Nick
[/b]

This thread is not about an oil leak it's about oil being consumed (and quickly). Also, doesn't the v6 take (with a filter change) 5.5qts (03) and 6qts (04+) so 5qts would be low to start with.
 

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thanks for the insight...please re-read post... I did not state there was a leak...but rather there was no leaks! implying it was consumed (quickly)..... in addition to be precise yes 5.5.... in any event irrelevant for the purposes of this thread...

I was inquiring to someone that could be of help...not someone who is going to critique the post

in addition the reason for the quick post was a state of panic when I got the call from dealer... currently am being told by dealer that it is not being covered by warranty
 

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I need some serious help here guys... brought my car in to dealer due to a loud tapping from engine... got a call and they tell me not a drop of oil in engine.... very odd... I personally changed oil like 1000 miles ago... no leaks... and added 5 quarts... I also read somewhere else that there was other causes... gonna do some searching but anyone else have any more inut that would be greatly appreciated

Nick
[/b]
Here is the only input you need, the PCV valve is a crappy design, they haven't quite owned up to it yet. The crappily designed PCV valve shoots oil from the cam cover into the intake manifold, to which is burned off with the gas/air mixture inside the cylinders and then expelled in a blueish tinge of smoke out the exhaust pipes.
 

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thanks for the insight...please re-read post... I did not state there was a leak...but rather there was no leaks! implying it was consumed (quickly)..... in addition to be precise yes 5.5.... in any event irrelevant for the purposes of this thread...

I was inquiring to someone that could be of help...not someone who is going to critique the post

in addition the reason for the quick post was a state of panic when I got the call from dealer... currently am being told by dealer that it is not being covered by warranty
[/b]
I'm not critiquing your post, so no offense. It's an internet forum, so if you aren't specific, people are going to bring it up.

I understand that you did not find any leaks, you don't have to say that though, oil consumption is what this thread is all about. And the 5 qts thing, if you say 5, then that's all we have to go on. I was just making sure you put in the correct amount. Obviously, having low oil can damage an engine so it IS relevant. Since you actually put in the correct amount then it is not a problem.

Bottom line, get your pcv valve checked, like FordMan says.
 

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I would just like to add that after doing this one month ago, my oil level has remained the exact same. As with most of you I would lose some oil throughout the course of the month and would have to refill it, but not anymore :D . I'm going to inspect matters within the intake manifold during my next oil change. I hope I don't find oil caked on the EGR valve as I did last time.
 
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