Hi Everyone,
My 98 LeSabre is sucking vacuum at the oil filler tube. I just bought this car. It has 150,000 miles on it. I'm having problems with it sucking vacuum through the oil tube filter tube and I replace the manifold intake manifold upper a week ago and I don't know if it was sucking vacuum then before I change it or not. It also was making a hellacious noise coming from the intake the air intake where the mass air flow sensor is so I just thought that it was a warped manifold but it still makes that noise on Startup but back to vacuum problem I replace the PCV valve and it'* still sucking vacuum through the oil tube is there anything else I need to check I've read the posts on here some of them and I can't seem to find anyone that has the same problem as I do. thanks for all your help in advance I appreciate it.

Probably the lower intake gasket.

I agree with carfixer007 ^^^^^^^

. . . and:

If the "hellacious noise" is with the filter box disconnected, and the noise sounds like sucking, but very raspy sucking, and it gets more raspy when you turn the AC on full cold, then this is probably a normal sound that they all make.

Thank you very much and I will check into that

Induction noise, it being a V6 is part of that reasoning

I think it'* the fuel injectors that make that noise. It is during start up, lasts longer during cold starts, and gets slightly worse when the compressor clutch engages or it gets put into gear or whatever I've also notices that the sound can be provoked on a warm engine by lowering fuel pressure by bleeding fuel out of the test port. The closer it gets to stalling the more it makes the sound.

if you did a balance test and paid attention to the noise, i wonder what would be noticed?

Balance test?

injector balance test or a cylinder balance test, basically selectively removing a cylinder from the firing order in order to see if the engine runs significantly worse or no change

The cylinder with least change would normally be the trouble cylinder (spark plug, compression, fuel injector, etc)
If you did that, i wonder what would happen

Basically, if its all the injectors or if its a few of them

Ah, I see.

This is a normal noise inside the induction tract. They all do it. At least every naturally aspirated Series 2 and 3 I've come across. I think it is the sound of the injectors spraying just by the behavior, but I don't know what it is for sure. I don't see it as a problem . . . except for how the air boxes are so restrictive to keep the noise under control.