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PCV Vacuum Leak After Catch Can

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Old 01-08-2019, 10:12 AM
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Default PCV Vacuum Leak After Catch Can

So I have a '12 Silverado with a 6.2L that I recently installed a cheap catch can on. Well the catch can leaked so it started throwing lean codes. I sealed up the catch can fittings with RTV, and confirmed it was sealed with a pressure test but I still kept getting the same lean codes. So tried I bypassing the catch can and the codes still came back. I then removed the factory quick connect fitting from the driverside valve cover and put the hose directly onto the nipple and clamped it but it's still leaking. In fact I can hear it whistling! I can pinch the hose all the way right up to the valve cover and the whistling goes away. So figured the hose wasn't sealing on the nipple so I swapped back to the original quick connect fitting. Same whistling. I'm out of options here, could the PCV valve inside the valve cover be bad causing the vacuum leak?

I do want to add that the catch does work and it has been catching oil. Here's what my install looks like:


Old 01-08-2019, 11:03 AM
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It's hard to say without a close up of the suspected fitting/connection. Is it possible the intake is cracked around that fitting or needs some thread tape? I'm not certain how that interfaces with the manifold.
Old 01-08-2019, 01:09 PM
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Ok, I have nothing to add yet except that I have that EXACT can on my Buick, and I too have a vacuum leak. I welded -8 fittings to mine, and have it routed differently. I also replaced nearly every gasket on that motor when I bought the car, so I can't say the can is the problem, but now I am curious.
Old 01-08-2019, 01:44 PM
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Originally Posted by BudRacing
It's hard to say without a close up of the suspected fitting/connection. Is it possible the intake is cracked around that fitting or needs some thread tape? I'm not certain how that interfaces with the manifold.
The connection at the manifold just pushes in and has some lock tabs and an oring that seals it but I think my problem lies at the other connection at the valve cover. If my leak were elsewhere then my pinching off the hose wouldn't stop the leak.

Originally Posted by arthursc2
Ok, I have nothing to add yet except that I have that EXACT can on my Buick, and I too have a vacuum leak. I welded -8 fittings to mine, and have it routed differently. I also replaced nearly every gasket on that motor when I bought the car, so I can't say the can is the problem, but now I am curious.
It's a decent can for the price but it's not turnkey. Mine leaked at each port and the dipstick so I put some rtv on the threads and an oring on the dipstick. Either way still way better than spending $300+ on a slightly nicer one.
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