Valve Cover Breather

[Black97]

Was reading about valve cover breathers and that tey should be a god thing.

Anybody can tell me the why's and how's, pro's and con's?

Would the K&N type (see link) or similar work for my 97 T/A?


http://store.summitracing.com/produc...earchtype=ecat

[RangerBob]

A few people have that. I think the Wolfman has one. It should help reduce some water moisture in oil. You might have to ensure you have enough clearance for a shock tower brace. I would like to get one too that will will fit the stock valve covers.

[Injuneer]

Your 97 (and in fact all 4th Gens) already has an extremely effective PCV system that keeps harmful vapors, including water vapor out of the crankcase. METERED (94-97 only) and FILTERED air enters a port in front of the TB blades, flows through the hose that runs from the TB to the passenger side valve cover, sweeps through the crankcase and the lifter valley, and is pulled out from the bottom if the intake manifold by vacuum in the PCV valve. The vapors then flow to the front of the intake manifold (95-97 only. 93/94 have a u-shaped hose that dump it into the side of the intake), to a port under the TB and enter the intake manifold where thye are burned.

"Opening up" the system simply allows the air to enter the system at the breather, technically opening up a small vacuum leak to the system, since the air is no longer metered by having passed through the MAF sensor. Nothing the long term fuel corrections can't handle.

A breather is essential on a blown engine. It is little more than a decoration on an N/A or nitrous motor, IMHO. My engine still has the factory system intact, at the 800HP level, and I have never had a problem with the "intake manifold leak".

[wolfdogs]

if you read my "fix" for the intake maifold leak...you will see how the breather helped me in my situation. a gm engineer at the poncho nats. agreed with me in 1998 that it can help on some enignes with the intake leak problem.... mines been on for 6.5 yrs and 50k...no problems. the one on the hawk has been there 6 yrs and 73k miles..no problem.

when we do the emission test... we take them off and put on the stock closed system tower and cap.

[Black97]

Thanks guys for sheding some light onto this matter and taking the time to explain.

Based on that I will leave mine the way it is.

Rene

[AmericanZ28]

I knew there was a drawback to messing with the crankcase vent system. But what about the tube itself, mines all cracked at the TB fitting, is it time to replace?

[Injuneer]

If the line from the TB to the valve cover is cracked, you definitely want to replace it. Depending on throttle postition, you are either pulling dirty, unfiltered air through the crankcase, and into the combustion chambers, or dirty/unmetered air through the TB and into the combustion chambers. Not a lot of air involved here, but why take a chance.

You may also find that the line, the top of the TB and in severe cases, the throttle body ports and blades get crudded up with oil. That MAY be an indication 1) your PCV valve is clogged and not working, 2) or that you have excessive blowby on the rings, and are pressuring the crankcase and blowing the vapors and oil backwards into the TB. It isn't unusual to get a little oil in the top of the TB (look under the little cover on top of the TB), specially if you tend to drive a lot at WOT....

[M3EATER - GG '00 WS6 T/A]

Thanks, Fred, for pointing out something that some of the guys may not have realized.....

On these late model EFI systems (BMW too), the complete crankcase is part of the closed vacuum system. opening anything up ... even a loose oil dip-stick .... will introduce unmetered air in to the intake system.

Now, granted, the PCM will adjust for a small amount, but if you want everything running "as planned" then make sure you have no cracked hoses or loose fittings, dip-stick, oil cap ..etc.

These LT1s are getting to the age (time wise... even if it has low miles) that the hoses are getting hard & brittle ... or .. soft and spongy if soaked with oil.

Gordon
www.provenperformanceconcepts.com

[Rob]

Very well said, Fred. I agree they are totally useless on a N/A app.

Blown, you can't have enough

[AmericanZ28]

Thanks Again Fred!

I'm defenetly going to replace that hose Immediately, and while im at it, it wouldnt hurt to chage the PCV valve . My car has almost 108K and I dont think its ever been changed. Anyways, thanks fred!