When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hello everyone, I believe I have an issue with crankcase pressure (I think). I have just rebuilt the engine, and just yesterday the rear main seal started leaking (the brand new cover and gaskets with seal already pressed into the cover). Therefore I think there might be something wrong with the crankcase pressure being too high. Here is my PCV routing with a catch can (I have just put a little breather filter on top of it, hoping that can maybe fix it). Also, I do not have a PCV valve anywhere, I believe there should be one in the driver-side valve cover but since I changed them there is no Pcv valve in there. Should I add the pcv valve? How can I test whether I have high crankcase pressure or check that my pcv is working? Not sure whether I should keep the filter on the catch can or plug it.
It should NOT have a "breather" anywhere, if this is still a MAF system. This is because it allows air into the intake that hasn't passed through the MAF, therefore the ECM isn't aware that it's there, therefore it doesn't add fuel to go along with it.
Correct routing is the way it's shown in the drawing. Clean filtered air at atmospheric pressure from downstream of the MAF (therefore has already passed through it and gotten metered), at the front of the TB ahead of the blade, is supplied to the one VC. The other should have the PCV valve or orifice, which is routed to the TB port that's behind the blade where there's vacuum, and contaminated air is drawn into there and sent to the engine to be burned. You have the catch can at the spot where it's best positioned to allow excess oil and other liquids to collect before being drawn into the intake. A breather on the can will also take away the vacuum that SHOULD be getting applied to the driver's side VC and allow air to bypass the whole PCV system, completely defeating it and rendering it totally ineffective. Just altogether the wrong thing to do.
Pretty easy to see if your system is effective: all you have to do is take off the oil fill cap while it's idling, and put your hand over the hole and see if there's vacuum (lower pressure than atmospheric) in the crankcase. The engine should run noticeably different with the oil cap off and the hole exposed.
If you have no PCV valve or orifice, just a hose nipple on the driver's side VC, then there could be SO MUCH flow through the whole system at idle, that the ECM might not be able to control the idle speed.
Thank You for the responses, I’ll take off the filter from the catch can, and I’ll plug it. So I do need the pcv valve then correct ? If possible please tell me what color of the hose to put the pcv valve on . I appreciate it.
Also, I hope that I just misaligned the cover, I’m in the process of taking the transmission out and will be replacing the seal with oem, I’ll be using the alignment tool, and press it in once it’s centered , hopefully it was just misaligned.
The PCV valve or orifice goes in the "yellow" hose.
Per Che70's comment re. alignment, the oil pan in these motors is a structural element. It must be aligned to the block and the cover. The cover must be aligned to the crank, but that can create misalignment between it and the pan. It's more complicated than it looks.
Note also, the threads in the holes in the cover for the 2 long bolts that hold the corners of the pan to the cover, often strip out; they're kinda small, and real fine, and only go into aluminum. I'd STRONGLY recommend a Heli-Coil for them before putting it on a 2nd time.
Thank You everyone for the support. I'll be installing the cover and seal tomorrow using the aligning tool. Also, would You guys mind sharing a link to a pcv valve since i cannot use the normal one that should be integrated in the valve cover.
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.
5.3LS Crankcase pressure issue PCV routing 
