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8.1l turbo, crank case pressure? help?

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Old 08-30-2011, 07:59 PM
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Default 8.1l turbo, crank case pressure? help?

so ive got my turbo finished up and took it for a ride... im still in the early stages of tuning for now then i will take it to a pro...

anyway it seem the turbo has pressurised the crank case becuase i developed a major oil leak, so upon inspection the turbo has managed to blow the dip stick tube out of the block which cant be good. lol... So, after reintalling it and looking at the stock set up i decided to drill the throttle body from the top into the factory passage way, and blocked off the small hole on the left side of the throttle body. I then installed a fitting and a hose on it.. my thanking was this would "vent" it instead of blowing it back into the throttle body like they do stock wich would fix my problem...

I took it for a second ride and it has fixed the dip stick problem up to 7 psi which is as far as ive gone for now... However the hose and fitting are now pulling vaccum...

so i guess my question is wth, how is it pulling a vaccum? and will it hurt anything? the 8.1L dont have any breathers in them... so im really out of ideas unless i can some how drill the valve covers which will be a total pain in the butt with the coil packs on top...

Any thoughts or info would be grate...
Old 08-30-2011, 08:51 PM
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Originally Posted by Kerr
so ive got my turbo finished up and took it for a ride... im still in the early stages of tuning for now then i will take it to a pro...

anyway it seem the turbo has pressurised the crank case becuase i developed a major oil leak, so upon inspection the turbo has managed to blow the dip stick tube out of the block which cant be good. lol... So, after reintalling it and looking at the stock set up i decided to drill the throttle body from the top into the factory passage way, and blocked off the small hole on the left side of the throttle body. I then installed a fitting and a hose on it.. my thanking was this would "vent" it instead of blowing it back into the throttle body like they do stock wich would fix my problem...

I took it for a second ride and it has fixed the dip stick problem up to 7 psi which is as far as ive gone for now... However the hose and fitting are now pulling vaccum...

so i guess my question is wth, how is it pulling a vaccum? and will it hurt anything? the 8.1L dont have any breathers in them... so im really out of ideas unless i can some how drill the valve covers which will be a total pain in the butt with the coil packs on top...

Any thoughts or info would be grate...
I believe the 8.1 have a orifice type PCV on the bottom of the intake manifold to the valley tray. You have to pull the intake off and plug that off, then you can just run the crank case vented or to a catch can.
Old 11-08-2011, 07:22 PM
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You are correct KB
Old 11-14-2011, 04:12 AM
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Originally Posted by xx_ed_xx
you are correct kb
x2 ^

pcv=pita
Old 11-14-2011, 08:12 AM
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Can't you drill and tap the top of the oil fill? Thats how I did one of my breathers.
Old 11-19-2011, 08:34 PM
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I pulled the vent tube under the intake. Then taped and screwed in a check valve. I also drilled and taped the valve cover and vented to a catch can.
Old 05-31-2012, 11:11 PM
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hey guys, i recently bought a 2006 sierra with the 8.1L.
I currently have the intake manifold off and sitting in my garage. I will post pics when i can.
Before reinstalling I'm wondering whether i should plug the pcv tube in the intake and run a traditional external pcv setup ? looking inside the intake it's all brown/black with oil varnish. I was getting P0101 MAF out of range on my first drive home from the dealer, among other problems. I just don't know how reliable this internal pcv system is because you can't see it.
Attached Thumbnails 8.1l turbo, crank case pressure? help?-a1.jpg   8.1l turbo, crank case pressure? help?-a2.jpg   8.1l turbo, crank case pressure? help?-a3.jpg  

Last edited by 1 FMF; 05-31-2012 at 11:28 PM.
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