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Started smelling burning oil and noticed the passenger side breather is leaking oil onto the header. Got me thinking if I even have correct setup as I really just have breathers on both valve covers and no PCV. Moreover, upon inspection the breather has a little white milky residue inside. Same on underside of oil fill cap. Not using any coolant that I can see. Drained oil and it appears fine with no discoloration or residue. Seems like there are differing opinions on breathers, PCVs, and what is required. Looking for suggestions on a simple setup and whether the leak/blowby is a potential issue. Separately should I be concerned about the white milky residue. 455 running e85. Torker manifold, Lunati custom cam with full roller assembly.
...I really just have breathers on both valve covers and no PCV.
...the breather has a little white milky residue inside. Same on underside of oil fill cap. ...should I be concerned about the white milky residue.
Seems like there are differing opinions on breathers, PCVs, and what is required.
Looking for suggestions on a simple setup and whether the leak/blowby is a potential issue.
Every engine has blowby. One of the products of combustion is water and when this blows by the rings, it settles in the oil. When the oil gets hot, the water evaporates and either is drawn from the engine or it condenses on cooler surfaces like the oil filler cap, breather, under the intake manifold, and inside the valve cover surface.
At first, this condensation appears as water drops or a mixture of oil and water (milky-looking). Eventually the condensation areas become coated with a solid sludge.
As far as differing opinions on PCVs and breathers, the car companies have always used some way to draw harmful moisture vapor from the engine. At first it was the road draft tube which used car speed to draw air through the engine. That was a passive solution and didn't do a very good job.
The PCV was introduced in the mid-1960s as a positive way of drawing moisture and oil vapor out. The idea was to have breathers in the valve covers that would let air into the engine and the PCV valve would draw that air (and water vapor and oil vapor) out of the engine.
If you don't have a PCV, the vapors constantly exit the engine through the breathers, carrying oil and water vapor with them. As you found, that makes a mess. If you want to stop the mess on a road-driven car, you should have a PCV.
Racers may not use PCVs but their engine hours are much lower and they overhaul often enough that sludge is not a problem for them. And you will see that racers put absorbent material over the breathers to soak up the oil vapors to keep them off the engine and the track.
Standard-performance Oldsmobile engines usually had the PCV on the driver-side cover, but it doesn't matter which side you use. The breather was on the opposite side and it was plumbed into the air cleaner so any oil vapor at full throttle could be contained.
High-performance Olds engines sometimes had breathers on each valve cover and an intake-mounted PCV. They did this because there was potentially more blow-by on the high performance engines and the dual breathers limited any pressure buildup inside the engine.
Mine is a ‘68 but doubt that matters as I have a 455. Not sure what is classified as a high performance motor, but I’m Not trying to be stock under the hood. My motor was set up as a drag motor but is now detuned to be a street motor. it had a a breather on the driver side with a hose running down towards the firewall and the passenger side was missing. Can I just do the same with the passenger side or are there benefits to use a PCV? Car is a driver but spends a lot of time at 6000 rpm.
...are there benefits to use a PCV? Car is a driver but spends a lot of time at 6000 rpm.
Benefits of a PCV on a street car are
cooler surfaces like the oil filler cap, breather, under the intake manifold, and inside the valve cover surface will not become coated with a solid sludge
you will avoid corrosion of internal engine parts (water in the oil forms an acid)
Is that really necessary? Seems like the answer to the question no one asked.
From the OP: Seems like there are differing opinions on breathers, PCVs, and what is required. Looking for suggestions on a simple setup and whether the leak/blowby is a potential issue.
Unless this is your daily driver, moisture builds up internally from periodic driving or short trips. A proper PCV system helps evacuate the blow-by, moisture, and acidic gasses. As long as the crankcase is generally run under a SMALL vacuum, this problem will cease to exist (assuming there is not excessive blow-by due to something like a ring failure). A proper PCV valve will help keep your crankcase under vacuum.
cooler surfaces like the oil filler cap, breather, under the intake manifold, and inside the valve cover surface will not become coated with a solid sludge
you will avoid corrosion of internal engine parts (water in the oil forms an acid)
In addition to the above, the PCV will prevent exhaust blowby gases from getting into the passenger compartment and gagging the occupants. I had my PCV disconnected for a brief period of time and the gases coming out the valve cover breathers was noxious.
April 20th, 2020, 09:11 PM
