pcv valve

[Spyke]

hi guys, I already asked the question somewhere else and never had an answer so I'll try again

what exactly does a pcv valve in today's car? And also, does the 3.6l in the cts have one? I'm asking because I have now almost 90k miles on my 05 3.6 automatic and I'm used to change the pcv valve on my previous cars but now the dealer told me I dont have one in my cts..

Can someone help me to clarify my question?

Thanks a lot !

[Messatsu]

Engine Crankcase Ventilation Fitting

The 05 CTS has a "makeshift" PCV valve, being a fitting rather than a valve on both the left and right side cam shaft covers. We've never/very rarely changed one on any of the 04-09 CTS's that contain this part. Unless you've had extensive engine damage via accident, I wouldn't worry about it. For deeper info on the phasing out/evolution of the PCV valve, I'd wikipedia it.

Messy~
Cadillac/GM Parts Guy

[Spyke]

Originally Posted by Messatsu

Engine Crankcase Ventilation Fitting

The 05 CTS has a "makeshift" PCV valve, being a fitting rather than a valve on both the left and right side cam shaft covers. We've never/very rarely changed one on any of the 04-09 CTS's that contain this part. Unless you've had extensive engine damage via accident, I wouldn't worry about it. For deeper info on the phasing out/evolution of the PCV valve, I'd wikipedia it.

Messy~
Cadillac/GM Parts Guy

Thanks a lot Messatsu, very appreciated! I've been looking for 30-45 minutes trying to find the pcv valve and now I know why I didn't find it! Viva la technology! Less maintenance to do

[ewill3rd]

A few year back they changed over to a metered orifice rather than use a spring loaded valve.
It is easier to manage as far as the computer goes and it is obviously cheaper.
Some models use a "separator" type device too but I don't see many of those anymore.

[Spyke]

tks ewill3rd, very appreciated! How do you know when to change them or what are the symptoms of those going bad?

I'm asking because I'm at 92k miles on my 05 and next week, I'll do a major tune up on my car.

[ewill3rd]

You can replace them (if you have one) as part of your regular maintenance. I think I have seen 3 bad ones in the 16 years I have been wrenching.
They will carbon up after a long time but rarely ever really go "bad".

There are two "test" for a PCV. Pull it out with the engine running and put your thumb over the end, you should hear the valve click, then remove it, you should hear it start to flow again.
Test two is shut the engine off and shake it, if it rattles it is good.

Some 3800's you cannot do this because they are inside the intake in a serviceable sealed passage. Those I just replace but you have to be sure to install the o-ring on the new one or you'll have big problems ... long story.

[mikes2nd]

i think my car is gummed up. I am going to check out all the hoses for this psuedo pcv valve.

I have the 3.6 and the factory manual says there is pcv valve tubing.

I think this isnt rare for these cars.

[Jim's 06]

PCVs were first used in 1963. The idea is to route crankcase fumes and vapors back into the intake system for burning and "disposal". (Prior to 1963, crankcase fumes were vented to the atmosphere- not good). The PCV consists of a one-way check valve that permits vapors (under positive pressure) to enter the intake, but prevents an intake backfire from going "upstream" back into the crankcase. The PCV can be very difficult to locate on some engines (the B-O-P 3.8/3800 comes to mind), and some cars either don't have one, or use some other device (apparently including the CTS).