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BBK Intake with LS6 valley----Intake Leak

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Old 09-09-2013, 08:44 PM
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Angry BBK Intake with LS6 valley----Intake Leak

I recently did the LS6 valley cover swap on my car and now I have an intake leak on cyl #7. I have the BBK intake with 1 low-profile bolt in the passenger side rear. And I did cut the piece out of the block. I've already pulled the intake back off once to check if the gasket may have slipped somehow but all looked good . So I just threw the intake back on and it was still leaking at the exact same spot. The booster hose is on and so is the small hose on opposite side. NOTE *The LS6 valley cover does come with bigger (13mm instead of 10mm bolts) But I still used the low-pro on passenger rear.* I'm thinking I need to go pick up a set of those low-pro bolts and use them in all holes because maybe the intake is hitting the drivers side rear 13mm valley bolt?

So if anyone else has the BBK intake with LS6 valley cover, please chime in!!!
Old 09-10-2013, 07:47 PM
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Update: Installed the low pro bolts on all valley holes and still is leaking on cylinder 7 at the top of where the head and intake meet. You can hear it sucking air and when you put your finger over it, the pitch changes. So once again, I pulled the intake and i'm trying to look over everything but no luck.
Old 09-10-2013, 08:49 PM
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It wasn't leaking before, so I would think it has to be something either blocking it from sitting flush or maybe a bad gasket on that port of the intake.
Old 09-10-2013, 11:39 PM
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If you're still using the LS1 steam tubes then you probably need to use the LS6 front steam and rear steam tube block offs. I had to do that when I ran the bbk intake, even with the LS1 steam tubes slightly flattened.
Old 09-11-2013, 05:49 PM
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I'm using the LS6 coolant tubes. Brand new felpro gaskets and they look perfect. Have pulled the intake probably 6 times now. Cant find anything hitting it. Intake sucks down onto the heads but still somehow leaks at #7. Have swapped gaskets from runners to 7 and still a leak.
Old 09-11-2013, 09:03 PM
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You tightened the intake in the correct sequence?
IMO, there must be something you're over looking.

Last edited by 99Bluz28; 09-11-2013 at 09:10 PM.
Old 09-12-2013, 07:28 AM
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Originally Posted by 99Bluz28
You tightened the intake in the correct sequence?
IMO, there must be something you're over looking.
Yeah I tightened to what GM recommends. But this last time I ran down #7 some first then went and did the rest and it seemed to help. Drove it around and idles at about 14-15 AFR which is what it was before. WOT is still 12.5 lol. You can still put your finger on that runner and hear a tiny bit of sucking but not as bad. So I think i'm just going to leave it alone.
Old 09-12-2013, 07:36 AM
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have you checked it with a straight edge , maybe its not a level surface anymore.
Old 09-12-2013, 01:44 PM
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It's important you follow the torque sequence, and you will need to repeat it as many times as necessary until all the bolts remain tight. I normally need to repeat the torque sequence 4 times until all my intake bolts remain tightened.
http://ls1engines.com/tech/wp-conten...ads/intake.gif
BTW, did you double check to make sure the valley cover is pulled all the way down when tightened.?
Make sure knock sensor wires are not routed over high spots(bumps) on valley cover, and make sure the wires don't show signs of being pinched(flattened)..?

Last edited by 99Bluz28; 09-12-2013 at 02:04 PM.
Old 09-12-2013, 05:51 PM
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Yes I followed the torque sequence every time. I have access to GM service information (tech at dealership) and even doing the sequence it leaked. Yes the valley is all the way seated the knock sensor wires are out of the way i've even put putty down in areas to check if it was touching. I did check the intake and heads with a straight edge and there was no gap.
Old 09-14-2013, 02:56 PM
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Ok so I forgot to mention I also did the trunion rockers while the intake was off. Aaand i'm thinking the valve cover gasket may be torn. Could that cause a vacuum leak?
Old 09-14-2013, 03:17 PM
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I'd go a head and Check the VC gasket then and look for signs of oil leaking around the gasket seal. So is the PCV tube that plugs into the rear of the driver side valve cover fully seated and not damaged?
Old 09-14-2013, 03:39 PM
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I pulled the valve cover off and it sure was ripped! Right by the intake so I was thinking it was the intake the whole time. My car is a 98 so I didn't use the plug it's more of a cap but yes it's brand new and air tight
Old 09-14-2013, 05:20 PM
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Well I hope replacing the VC gasket/seal solves you problem.
Old 09-15-2013, 10:29 AM
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Went and bought a new VC gasket and when I got back my catch can arrived! So I installed both and fired it up. NO more leaks anymore and the wideband proves it lol. Thanks for the help 99blu I appreciate it
Old 09-15-2013, 01:34 PM
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Good to hear that solved your problem.



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