LSrBEST

Hey guys I've been researching this for awhile and I was hoping to gain some more understanding. Engine is as listed in my sig. I just made the NNBS and 87mil intake swap last weekend from the stock LQ4 intake that I shaved. Prior to this weekend I had ran both vents into a tee then at the port @ the TB that was it. No breathers no nothing, All seamed well. I never put anymore thought into it as I never had problems however I never quite understood the importance of vacuum in the crank case and it's importance until the NNBS swap. I did not shave it as I didn't have the time so I ran one valve cover breather to the port mid intake and the other has a filtered breather as I chose not to tap into the intake boot/snorkel. First test run after swap I had the usual problems until I hooked up HPT, but I also had check oil level light come on. Oil was just changed 200 miles ago, I checked it with engine running and I had 0 oil on the dip stick. I knew that was impossible so I tried to pull the oil fill cap off and the vacuum was very strong. Never before have I had this issue.didnt think much about it other than perhaps the new intake breathed that much better and the fact that my last PCV routing probably just didn't creat sufficient vacuum (I now know why) lol anyways the last 2 days I've noticed oil burning at start up. I know it's from the oil being sucked into the intake. I've checked the lines and obvious signed of extreme vacuum. Anyways I understand the whole catch can thing and I'm completely aware of the situation and essentially how to deal with it, what I'm not 100% sure of is the amount of vacuum needed and how significant is it? Should I try to measure this and be within X amount? Also while swapping intake I replaced #7 intake valve spring and bent pushrod as it was broke. 4000 miles on new build and valve train was all new. Comp bee hives. All was rated accordingly, never sees more than 6200RPM's, auto. Trans so I'm not missing shifts. Just my DD could this have been caused by the lack of proper vacuum prior to NNBS swap? Also I I've bwwn leaking oil since the build. Thinking rear main. It's not bad and Im going to deal with it this winter could this have been cause my internal preassure build up? Never had any extreme positive or negative preassure when pulling oil fill cap when running before intake swap if that helps. Thoughts and knowledge is appreciated! Thanks!!

MikeGyver

iTrader: (5)

Do you have a PCV Valve in the hose that goes to the intake manifold? Did you see replace the #7 intake valve guide seal?

LSrBEST

No valve seal it looked good. Funny thing I found out last night after this post that there is a PCV valve. Never knew this. Has to be why it was sucking oil. I'll address that today. Still has me wondering tho if that's the root cause of the broken valve spring,

LSrBEST

Back on this subject. Struggling a bit. Block is an '05 LQ4, heads 243's with the '05 LQ4 valve covers, intake NNBS. current PCV routing is coming from passenger side valve cover to intake manafold at top/port, the drivers side valve cover just has a breather. Providing I'm not comsuimng a ton of oil what are people's thoughts. Are the sides different? I'm gathering that some of the truck valve covers have the PCV valve in that nipple. Currently I have no actual PCV "valve" rather just a ventilation routing. Should be working towards fitting an actual valve to control vacuum? I had ran this current set up the other way around (driver side plumbed into intake with breather on passenger side but it sucked oil! I thought perhaps that was in the baffle design but now I'm thinking the PCV "valve" is what controls that oil issue. Anyways the current set up has much more vacuum when I remove oil fill cap when trucks running that when I had it plumbed with the drivers side into the intake. Thoughts? Thanks!

MikeGyver

iTrader: (5)

If you insist on putting the crankcase fumes back into the intake manifold, then yes. A sure way to keep the engine from getting oil into the intake manifold is to plug the fitting on the manifold and run both valve covers through a catch can and to the atmosphere. You will smell some fumes, but at least you will be keeping plug fouling, detonation inducing, cloud forming oil out of the intake. And no, this didn't break your valve spring.

MikeGyver

iTrader: (5)

Does your truck have an electronic throttle? If not, it might not get enough idle air through the IAC and need a tune or other adjustment.

LSrBEST

It is DBW, I have HP tubers and it’s running well. So I don’t have any idle issues as far as it running and if so I’ll adjust but my main concern is vaccum or lack there of. I’ve noticed since I’ve had the set up as is (showing lots of vaccum at oil fill cap) I’ve stopped pushing oil out of my rear main, which until now I thought was a build error as I did it. If I’m not sucking too much oil now I’ll leave it as long as it’s not to much vaccum. If it’s suckint oil will instal a catch can. I guess what I’m wondering is if I have that much vaccum all the time is it bad?