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Repair Guide: Pcv diy

Old 05-05-2005, 11:04 PM
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Join Date: Aug 2004
Location: Tomball, Texas
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Default Pcv diy

PCV Filter update....

This was found on ImpalaHQ.....

Replacing the PCV Valve

While an engine is running, a small amount of the combustion gases leaks past the piston rings into the crankcase. This is commonly referred to as blow-by. The crankcase ventilation system directs crankcase vapors back into intake manifold to be consumed in the combustion process instead of allowing it to escape into the atmosphere. This is controlled by the PCV valve. For some reason, in the service manual this valve is called the PCV valve in the section dealing with the 3.4L engine while it is called the crankcase ventilation valve in the 3.8L engine section. I am going to use PCV valve just for consistancy.

The first part of this article is for the 3.8L engine. Dan send me photos for the 3.4L engine and it is located where I would expect it, in the valve cover. Scroll down the page for his photos.

Credit for this article goes to Mattmcdill and 00Impala from Edmunds. They wrote the article, I just took photos.

3.8 L Engine
Where the *%#@^!! is the PCV valve?!?! I am used to it being in a valve cover. Turns out it is under this cap.

Strangely enough, there is an electrical harness attached to it, which is why I would have never figured out that it was under there without Matt pointing it out.

To get the cap off, you need to remove the fuel injector sight shield (how does Chevy come up with these names??). Clean the area around the oil fill cap and extension tube to prevent things from falling into the engine. Twist the oil fill cap counterclockwise and remove it. Do the same for the tube. You don't have to remove the cap from the tube, it was just easier to grab onto the tube with the cap off. Again, carefully clean the area to prevent stuff from falling in.

This is what the oil fill cap and extension tube looks like.

The shield is held into place by the extension tube and a tab that goes into a hole in an engine bracket mounted near the firewall. Watch out, there is a rubber cap on this tab and it can come off and fall into the engine bay and you'll never find it again.

This is what the rubber cover looks like just before it falls off into the engine compartment. Just push it back on.

Here is the "fuel injector sight shield." Put the oil cap and extension tube back into the valve cover.

The PCV valve is under this cap. It is located on the passenger side of the engine. That is the alternator on the left side of this photo.

Remove the electrical connector by lifting up the tab and gently pulling. The arrow is pointing to the removed connector. Then gently push down and turn the cap counterclockwise. It is spring loaded and is similar to a radiator cap.

Here is the PCV valve attached to the cover. Notice there is a black o-ring on the bottom of the valve.

The valve may not come out with the cap. This is what you would see if this happens.

This is what the whole thing looks like when you take it apart. Inspect the o-ring for damage and replace if required.

There is another o-ring for the seating surface of the cap. There may be a lot of debris around the o-ring.

Note from Taz: The pictures were hosted by another site and are no longer available.
Old 05-22-2009, 10:31 PM
Join Date: Oct 2007
Posts: 9

I am unable to view the pics - would you either resend or let me know where I could view them? Tks Tony
Old 05-22-2009, 11:11 PM
Join Date: May 2008
Location: McAllen,Tx
Posts: 383

Montejass i got a question for you, im not sure how much knowledge u have about the pcv valve (kinda stupid putting valve at the end considering the "V" in pcv mean valve but n e ways) just wondering if you would know why changing the valve would change the sounds of a cold air intake.... for example, my intake would sounds like if it would be sucking up alot of air and then released the air all at once then when i changed the valve it sounded like if the air was let out slowly instead of all at once..... thats one that thing that changed the second thing would be when the car is running hard its starts chirping like a rooster.... when i remove the oil cap it stops the chirping would you say i would have a vaccum leak or something that would be affecting this at all or what would it me any input on this would be much appreciated thank.....
Old 05-23-2009, 12:24 AM
Join Date: Aug 2008
Location: Philadelphia, PA
Posts: 722

sprfrk2005 - That sounds like you might have a vacuum leak to me.
Did you change anything besides the PCV valve?
There is a little black rubber o-ring that goes on the PCV valve. New PCV valves usually do not come with these o-rings.
Did you make sure to swap the o-ring over to the new valve? Did you inspect the o-ring for damage like it says in the OP?
There should also be an o-ring under the PCV cover. Did you make sure that o-ring is still in place, and make sure that it is not damaged or dry-rotting?
I would check to make sure that the cover is properly tightened as well.


PS. The "V" in PCV stands for Ventilation, not Valve. PCV = Positive Crankcase Ventilation

Is montejass even around any more?

Last edited by biggriggs; 05-23-2009 at 12:26 AM.
Old 05-23-2009, 01:02 AM
Join Date: May 2008
Location: McAllen,Tx
Posts: 383

Hummm... is that O-Ring suppose to be ON the pcv valve its self or were exactly is it suppose to be and if its missing or damanged will that create the vacumm leak or would that be something else? o0o0 and the name is ozzy bro and woops looks like i dont know that much bout mechnics hehe
Old 05-23-2009, 01:11 AM
Join Date: Aug 2008
Location: Philadelphia, PA
Posts: 722

The o-ring will be on the valve itself. It sits just below the "shoulder" of the valve to seal it up when you push the valve down into it's slot.
That would create an internal vacuum leak, although I don't think that's what you're describing.
I would definitely check the cover and the seal for the cover for an external vacuum leak.
You should have that o-ring on the PCV valve itself too. Check to make sure it is there.
Old 05-23-2009, 01:16 AM
Join Date: May 2008
Location: McAllen,Tx
Posts: 383

humm... ohhh ok ill check that tomorrow morning.... just a thought i know the sensor that sits on top of the pcv valve has a some what fitting type of rubber on it if its coming apart a bit would that affect the seal it crates or would that highly unlikly?
Old 05-23-2009, 04:23 PM
Join Date: Aug 2008
Location: Philadelphia, PA
Posts: 722

I'm not sure what sensor you are talking about (I'm not familiar with the layout of the sensors on the L36), but if the cracked rubber tubing is a vacuum line then it will cause a vacuum leak.
If you can find a pic, I might be able to tell you (or someone else could) what it is.
I'm guessing that your MAP sensor is right there, in which case I would definitely replace the tubing.

Old 08-31-2010, 11:27 PM
Join Date: Apr 2010
Location: Minnesota
Posts: 10

my 2003 monte SS, does the same thing on a cold startup, i have an intake, and it sounds like a lot of air is being sucked in. once i start driving, it goes to normal
Old 07-31-2011, 09:05 PM
Join Date: Jun 2011
Posts: 2
Default shucks:/ my first post and I'm clueless... so please excuse me

Here goes nothing:

Montejass if you are still out there...or anyone who can help

I read and reread this post about finding PCV valve and I have finally figured out that the pictures that went along with his post are lost in the World Wide Web of Abyss (or they were from another site).

The information given here is really good but my friend is struggling trying to find his PCV valve (I, myself, am not the owner of this poor baby of a car). If you (or anyone for that matter) can help by posting a pic of where exactly the PCV valve is located on 2004 3.8 (not supercharged) on their vehicle, I would be eternally grateful (like, I will name my second born child after you grateful:P)!! He's bound and determined to find this thing and he's nearly sliced off his thumb so far, so.... wish us luck!

Thanks in advance for any help with this elusive little bugger!

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