Explaination of OEM PCV vs LS6 VCT Mod

[SMWS6TA]

There has been a lot of questions about the OEM PCV setup vs the LS6 VCT mod and Catch Cans. I hope this can clarify some of these questions. i had posted this in another thread but decided to break it out so others can find this info easier.

Our cars have a crappy PCV system that over time can cause oil/vacuum leaks. IMHO GM screwed the pooch (<us) by using this is a POS PCV system and on top of it, over charging us ($85-$140 depending on where you get it) for when you need to replace it.

The PCV setup runs from the rear of the driver’s side valve cover behind the intake where it splits, one tube goes to the passenger valve cover the other comes along the passenger side of the intake into the PCV valve then into your intake. In the pics below you can see where it cracks and leaks.







Pic below shows the quick fix for the PCV.



You can spend the $85-$100 to get OEM that will in time need to be replaced again or you can do this:

Part #: VCT - 12577927

LS6 VCT (Valley Cover tray mod) with a catch can. Some like it some don't. This is not a performance mod but it does help get the oil out of the intake. It deletes the PCV tubing and puts the PCV under the VCT and moves the outlet port to the front of the engine underneath the TB. It moves the PCV away from a direct source of oil (valve covers) and moves it underneath the VCT. It still relives the crank case pressure, just doesn’t force as much oil into the PCV.

This mod cost about $58-$75 for the VCT and about 2-3 hrs of time. The catch can goes for $50-$220 depending on what you want for style and function. Some get twin catch cans, bigger, smaller; meaning you have options.



Catch can – its function is to filter the air/oil mix that blows by the PCV. By design, GM had the blow by go into the intake and then it would burn off. However most of the time it clings to the intake and over time begins to rob it of air flow and gunk up the pistons and such.




In the pic below it's been about 6 weeks since I did the LS6 VCT and installed a Catch Can.

I wanted to see how much oil it had caught. I drained it into a cup and was a little surprise by just how much oil I had.





Prior to this mod I had to use a ¼ quart of oil every month. It’s been over 2 months and I’ve yet had a “check oil” light come on.


Couple of more things to think about when doing the LS6 VCT mod or an intake swap:


The OPSU is the tall plastic piece that is sticking up with the green cap.


(you can also see in this pic just how much oil was getting by the OEM PCV. This pic was taken prior to me doing the LS6 VCT mod. My LS1 Intake also had as much oil on the inside.)



These can get brittle and break over time. Also when you are messing with the intake most first timers break it because they don't know it's there. These can leak quite a bit of oil. Signs of this are oil coming down the backside of the engine over the bell housing. It is commonly mistaken for a rear main seal leak.

99’-02’ Knock Sensors – 98’ and older GM is no longer making, If you’re like me you will need to upgrade to the 99’-02’ KS sensors (x2) and wire harness. Even if you have a 99’-02’ KS it is still a good idea to replace them. Remember it’s better to do it now while you have everything off then have to come back later.

Part #’s”
KS (x2) - 12589867
KS harness – 12601822


Check the Tech Stickies section in the General Help forum and you will find write ups on how to do the PCV hose mod and the LS6 valley cover mod. Hope this helps.

[cammed goat]

I think I will upgrade to a catch can soon since I am now on my 2nd motor and I want it to last.

[SMWS6TA]

I'm kinda hoping a mod will sticky it in the General Info Section.

I've been answering this same question for 4 months now.

[kingls1]

Very good info you answered the information I was looking for, Thanks

[JayTA98]

this mod will cost me about $272 shipped from gmpartsdirect because of the harness, sensors and bypass kit. Ouch. I guess ill hold off until i get my tax return.

[JayTA98]

I finally have the LS6 valley cover mod and it helped my idle tremendously. It was not cheap but it also fix this issue so i'm happy with the investment. I will strongly suggest to order the KS sensor harness. Mine broke as soon as I remove it. 1998 owners - if the harness breaks you WILL NEED new knocks sensors. GM changed the KS harness and knock sensors. The new stuff is not compatible with 1998 stuff. So order both.

Great write up SMWS6TA.

[sjsingle1]

git r dun

[jsmith564`]

please forgive me..

but to what year models does this mod apply? i have an 02. reason i ask is i don't know weather the 01/02+ just comes with the ls6 intake or the whole ls6 set up..

[SMWS6TA]

please forgive me..

but to what year models does this mod apply? i have an 02. reason i ask is i don't know weather the 01/02+ just comes with the ls6 intake or the whole ls6 set up..

All yrs 98-02 have the OEM PCV setup. The mod like stated before is not a performance mod, it is more like fixing a fault. I I said in post one it cost about $120 to replace the OEm setup, but to do the mod it cost about $60. I mention some other areas of concern like the knock sensors and harness, OPSU, and catch can. Those are things that either need to be address or possible replace while doing the mod due to fact that if they go out later you'll be doing the same work again. Kinda like when you do a cam you also do a timing chain and oil pump* (* - if you have a 98')

With this mod the 02's and some 01's are lucky in that they have a LS6 block and would not be required to notch out a small section of the block in order for the LS6 VCT to fit proper. The notch is about 1/2" by 3/4". It doesn't hurt the block as long as you don't cut more then that.

The intake is a separate issue. 02's have the LS6 intake, some 01's do.

[JayTA98]

All yrs 98-02 have the OEM PCV setup. With this mod the 02's and some 01's are lucky in that they have a LS6 block and would not be required to notch out a small section of the block in order for the LS6 VCT to fit proper. The notch is about 1/2" by 3/4". It doesn't hurt the block as long as you don't cut more then that.

The intake is a separate issue.

I think the intake is 98-00 have stock LS1 intake.

[SMWS6TA]

All yrs 98-02 have the OEM PCV setup. The mod like stated before is not a performance mod, it is more like fixing a fault. I I said in post one it cost about $120 to replace the OEm setup, but to do the mod it cost about $60. I mention some other areas of concern like the knock sensors and harness, OPSU, and catch can. Those are things that either need to be address or possible replace while doing the mod due to fact that if they go out later you'll be doing the same work again. Kinda like when you do a cam you also do a timing chain and oil pump* (* - if you have a 98')

With this mod the 02's and some 01's are lucky in that they have a LS6 block and would not be required to notch out a small section of the block in order for the LS6 VCT to fit proper. The notch is about 1/2" by 3/4". It doesn't hurt the block as long as you don't cut more then that.

The intake is a separate issue. 02's have the LS6 intake, some 01's do.

I think the intake is 98-00 have stock LS1 intake.

I'm correcting myself. Starting in 01 all came with LS6 intake.

[TA98]

So im assuming that the new PCV hose connects to where that little red cap is? also what do you do with the stock system? just cap it off

[sjsingle1]

So im assuming that the new PCV hose connects to where that little red cap is? also what do you do with the stock system? just cap it off

you run a hose from the nipple (red cap) to the nipple on the manifold where the stock line went......you plug up the grommet in the driver side rear valve cover where the stock line was......and cap the rear nipple on the pass side valve cover

[JayTA98]

All yrs 98-02 have the OEM PCV setup. The mod like stated before is not a performance mod, it is more like fixing a fault. I I said in post one it cost about $120 to replace the OEm setup, but to do the mod it cost about $60. I mention some other areas of concern like the knock sensors and harness, OPSU, and catch can. Those are things that either need to be address or possible replace while doing the mod due to fact that if they go out later you'll be doing the same work again. Kinda like when you do a cam you also do a timing chain and oil pump* (* - if you have a 98')

With this mod the 02's and some 01's are lucky in that they have a LS6 block and would not be required to notch out a small section of the block in order for the LS6 VCT to fit proper. The notch is about 1/2" by 3/4". It doesn't hurt the block as long as you don't cut more then that.

The intake is a separate issue. 02's have the LS6 intake, some 01's do.

in addition to this i will say to get a KS wire harness or make sure that your local dealer has it in stock. The plastic tabs in the KS harness may break and you won't be able to reuse it. If you have a 98 you will need it but you have to buy new KS because the wire harness design has changed and it wont fit the stock KS on a 98.

[Firebirdjones]

What I found more interesting on SMW's post is how much oil he was still catching AFTER the LS6 PCV swap.

I still run the stock PCV setups on both of mine, and I catch about the same amount of oil in either car with a catch can as SMW is catching with his LS6 PCV setup. So it would appear to me the LS6 setup wouldn't be advantageous in the oil consumption department.
Which is exactly the opposite of what I figured would happen. Since the stock setup is pulling from the rear of both valve covers, right where all the oil sloshes every time you leave a stop light. GM had always put the PCV setups towards the front of the valve covers or in the front of the valley pan (depending on the brand) so why they went to the rear of the covers on the LSx platform is beyond me.

[jsmith564`]

All yrs 98-02 have the OEM PCV setup. The mod like stated before is not a performance mod, it is more like fixing a fault. I I said in post one it cost about $120 to replace the OEm setup, but to do the mod it cost about $60. I mention some other areas of concern like the knock sensors and harness, OPSU, and catch can. Those are things that either need to be address or possible replace while doing the mod due to fact that if they go out later you'll be doing the same work again. Kinda like when you do a cam you also do a timing chain and oil pump* (* - if you have a 98')

With this mod the 02's and some 01's are lucky in that they have a LS6 block and would not be required to notch out a small section of the block in order for the LS6 VCT to fit proper. The notch is about 1/2" by 3/4". It doesn't hurt the block as long as you don't cut more then that.

The intake is a separate issue. 02's have the LS6 intake, some 01's do.

just making sure. i wont go out of my way to do this, but if/when i do a cam i'll put it on the list.

[SuperSSguy]

I'm correcting myself. Starting in 01 all came with LS6 intake.

I have an 02 Camaro SS...do i have an ls6 intake?? Also do ALL ls-1`s have this pcv/oil pig problem?...Because ive seen my Throttle Body inside and its real clean,also i rarely have to add oil between oil changes...is this possible that i have a good working pcv system?

[SMWS6TA]

I have an 02 Camaro SS...do i have an ls6 intake?? Also do ALL ls-1`s have this pcv/oil pig problem?...Because ive seen my Throttle Body inside and its real clean,also i rarely have to add oil between oil changes...is this possible that i have a good working pcv system?

LS6 Intake - yes


LS1's = oil pigs yes. Mostly the 97-98's


Are you the orginal owner?

If you keep your maintence up and change your PCV at regular intervals you could be lucky. It also depends a little on your driving habits. Meaning if you don't do any hard launches, high revs you might not get much blow by. You could also have a crack on the back side on the back of the intake and have oil down the back side.

If you want to help the motor I recommend doing at least a catch can. The LS6 vallet cover tray is a good upgrade for you to. You're lucky because you don't need to notch the block like most of us need to.

[SuperSSguy]

LS6 Intake - yes


LS1's = oil pigs yes. Mostly the 97-98's


Are you the orginal owner?

If you keep your maintence up and change your PCV at regular intervals you could be lucky. It also depends a little on your driving habits. Meaning if you don't do any hard launches, high revs you might not get much blow by. You could also have a crack on the back side on the back of the intake and have oil down the back side.

If you want to help the motor I recommend doing at least a catch can. The LS6 vallet cover tray is a good upgrade for you to. You're lucky because you don't need to notch the block like most of us need to.

Yes i am original owner Bought it (ordered it )10 mi on when i got it! No cracks,No leaks, No residue clean and dry.I do some hard launches and high revs but not to access or abuse. ALSO..how does one tell if they have an ls-1 or ls-6 block? ( I read the sticky on telling the difference between F-bodies and for my year it said ''some'' have ls-6 blocks.) Thanks...

[Cutlass]

sticked this post!