Vented oil filler cap on c5z?

[froggy47]

GM has come out with a vented oil filler cap (TSB 1656273) due to icing causing the pcv to freeze in sub freezing areas.

http://www.cadillacfaq.com/faq/tsb/d...-06-01-014.pdf

I am fighting an oil leak, I believe due to high crankcase pressure (where front engine cover meets upper oil pan ls6).

Do you guys think this vented cap would help relieve some pressure during high sustained rpm conditions?

I have NO LEAK during normal operation. 45k miles.

:)

[stevebz06]

Sounds like like something worth trying, although you're not subjected to freezing temps too often, are you? Have tried a leak down test to see how your rings are sealing?

[froggy47]

Originally Posted by stevebz06

Sounds like like something worth trying, although you're not subjected to freezing temps too often, are you? Have tried a leak down test to see how your rings are sealing?

Thanks for the post, no I'm not subject to freeze, but thought it might work for blowby.

It only happens during "spirited driving" so I'm not going to do a ring job @ 45k miles for that. I'd get a new car first. It's widely known that GM put different rings in the various model years that did not stand up. There were many lemon law buybacks, some lawsuits etc. My 04 is supposed to have the "solution rings" but I'm getting engine oil leaks when driven hard. And nothing when driven regular.

Just hoping someone on this forum has come across the issue & has some thoughts.

How are race motors set up as far as venting crankcase fumes? Do race motors put the fumes into the intake?

[stevebz06]

Probably to the atmosphere, unless they have rules stipulating otherwise. My '01 uses oil when I race it, but it doesn't leak, but it has maybe 15,000 on it.

[stevebz06]

I just had a thought: do you overfill your engine oil when you go racing?

[froggy47]

Originally Posted by stevebz06

I just had a thought: do you overfill your engine oil when you go racing?

I over fill (per GM specific instructions) by 1/2 qt. GM specifies 1 qt. I have done this for the past 25k miles & it's only started leaking this season.

Not overfilling can result in the oil pump starving (cavitation) during high speed extended turns (think g forces and oil pooling in the upper engine) which can result in catastrophic engine failure.

[stevebz06]

I've been trying getting away from overfilling for autocross. You don't usually have sustained, high g turns in an autocross and I'm thinking it may not be necessary to do it.

[froggy47]

Originally Posted by stevebz06

I've been trying getting away from overfilling for autocross. You don't usually have sustained, high g turns in an autocross and I'm thinking it may not be necessary to do it.

I think you may be right, for autox (no sustained high G turns), but I don't think it's my issue as I have always overfilled for 25k miles & it's only now leaking. I will probably save the oil & let it level off at full & then just bump it up for track days.

You do have a lot of brief high G turns in autox. From what I have read, the LS engines thru gen III pump too much oil up to the valve cover area and have insufficient quick drain down. So it "might" still be an issue with autox especially on sticky tires. There are aftermarket push rods that some guys use that restrict some oil flow, but I like the engine as stock as I can keep it.

I may pick up the vented oil cap, my local dealer has one for about $15, maybe napa has one too, nobody can tell me what psi it vents at. Little details like that are nice to have.

Sure wish I knew an engine builder, they seem to have already figured out all this stuff. I'm guessing around and posting on 2 or 3 forums & getting all kinds of useless info.

:)

[c4c5specialist]

Hi there,

The simplest way to determine if you have abnormal crankcase pressure, is to install a vacuum pressure gauge in the breather tube of the engine.

Bring the engine to 3000 and see if you have any pressure. My guess is that you will not and have a slight vacuum.

Allthe best, c4c5

[froggy47]

Originally Posted by c4c5specialist

Hi there,

The simplest way to determine if you have abnormal crankcase pressure, is to install a vacuum pressure gauge in the breather tube of the engine.

Bring the engine to 3000 and see if you have any pressure. My guess is that you will not and have a slight vacuum.

Allthe best, c4c5

If I hook it up to the driver side valve cover tube (that is blocked off on the 2004 my) would that work? Or the pcv line coming out from the valley cover pcv system?

:)