Oil leaking into cold air intake?

Hello BBOYLILROB,

I wonder if there is a clogged oil passage or oil pressure is too high and oil is building up in the head.

What are you running for oil pressure? Are you using a performance oil pump?

Also, on the valve cover there is a baffle. It's possible it got clogged behind it or the weep hole on it is clogged and the oil can't leave fast enough.

Here is a video from an engine builder. It is on oil consumption, PCV system fail, but I think he has a good point. It might be worth removing the valve cover and make sure it can drain properly.

Here is the link:
https://youtube.com/watch?v=CePGNsAkcYQ&feature=share

Let me know what you find. I am going to keep looking on my end to see what else I can find for you.

Thank you,
Brendon

Hello BBOYLILROB,

Wow, that's a lot of oil.

So, you bought a new valve cover I am assuming and installed it the first time you did rocker arms and pushrods and lifters? Is that right?

Where did you get the valve cover from? You got a part number I would like to take a look at it.

Did you change anything in the valve train or just replace stock components?

Thank you,
Brendon

Hello BBOYLILROB,

That is what I was thinking as well. Especially under load you are at a higher RPM so the valve train would be throwing a lot more oil at it. That video I sent, the guy did just that. He drilled extra holes in that baffle on the valve cover so it would drain better.

On my Suburban, my PCV valve is on the driver's side cover by the fire wall. I have the LQ9 in mine. My information is telling me your engine, the L92 should have it on the driver's side as well. Is it just a tube on the passenger side? No valve? Is the valve actually on the driver's side? I will add a picture for you from my information. It is possible it's the wrong image. Let me know what you see.

If you take out the PCV Valve and shake it, can you here it rattling? It might be worth trying to throw a new one in there if it is questionable.

My thought is If the valve is on the driver's side, and it is clogged it could cause blow-by to build up and force oil through that tube one the passenger's side and into the intake since it will only have the one outlet instead of one on each valve cover.

Let me know what you find.

Thank you,
Brendon

Hello BBOYLILROB,

Looks like there might be one p/n 12567915 they are calling it a fitting, but I found something that said it had a ball bearing in it. But either way the cover is brand new so that's out as a possibility.

It shouldn't be the covers since it is only happening on one side, say if it were a redesign or something to the baffle. Unless there is something different between the covers. However, you didn't replace the covers until the second time you took it apart prior to that the valve train was already replaced and you were already having this issue but running the old covers. So that's out too.

Could possibly be a clogged oil passage. I would remove the valve cover and pour some oil in there and make sure it is able to drain properly. Let me know if you find anything.

For now, I am going to ask another expert and see if they have any ideas as well as look at a few things and see what I can come up with for you.

Thank you,
Brendon

Hello BBOYLILROB,

Okay, that's no problem. I have been looking all day for a diagram and been looking at pictures of heads trying to find where it drains. As soon as I find one, I will send it to you.

I did find something interesting though. According to my information, air is sucked through that hose into the right rocker cover via that formed hose. To reduce potential oil pullover into the throttle bore due to backflow of the ventilation system, the right rocker arm cover is shielded, that baffle, from the rocker arms. From there fresh air and gases are routed through the crankcase and up the opposite rocker arm cover where the PCV is located. Gases are then routed through a hose to the intake manifold.

So, there might be something affecting that process. Maybe vacuum. Vacuum does get lower as engine speed increases so that would make sense that it would happen more when under load like towing or WOT. I would measure vacuum using that hose coming out of the driver's side rocker cover to the intake and see what you get for a reading. If there isn't enough vacuum or it isn't pulling it around the engine for some reason the intake would end up sucking air from the hose instead of providing it and the oil along with it.

Maybe it wasn't doing it before because the parts were old, so oil was restricted.

Here is a video about oil passages I found. It's really good, has a lot of good information in it:
https://youtu.be/RxhG8wIBkEA

Let me take a look and see what other information I can get for you. I will add the whole explanation of the system from my reference information for you. Let me take a look and see if I can get a spec for you too.

Thank you,
Brendon

Hello BBOYLILROB,

Let me take a look at the mating surfaces and the gaskets and see. I know on the sbc it was possible to put it on wrong, but I think it blocked a coolant passage. But since these engines are all the same basic design, I would say it is possible. Let me take a look for you.

Thank you,
Brendon

Hello BBOYLILROB,

So, the head is symmetrical, but the gasket can only go on one way. I added a picture of the head gasket from Fel-Pro. I don't know if you can see it on the gasket, but it says "front", but it looks like it would block off coolant passages. So thankfully I don't think that's the issue otherwise it would be overheating.

Thank you,
Brendon

Hello BBOYLILROB,

Yes, I understand. It's frustrating. I go through it with mine too. I think the best thing to do is to make sure the hose on the driver's side of the engine is able to pull air through it and make sure it isn't kinked. That way we know we are pulling gases up from the crankcase because if it isn't the intake is going to pull air out of the passenger side and oil with it. If you have a scan tool I would check and see if it's running a little lean from an intake leak causing a low vacuum situation.

There is a Technical Service Bulletin (TSB) for oil leaks from the rear main seal. While the TSB doesn't say anything about an intake leak it mentions the PCV system and a vented oil filler cap replacement. Part number is 12589430. Maybe it will help.

Thank you,
Brendon

Hello BBOYLILROB,

Lol. Well, that's good, at least we know that's good too. It might be worthwhile to check the port though.

I found another TSB on oil consumption. I want to see if the part numbers you got are the updated ones.

Do you have the part number for the valve covers you bought?

Thank you,
Brendon

Hello BBOYLILROB,

Do they both have a baffle in it that looks like the one in the image?

Thank you,
Brendon