[cribbj]

Anyone looked at how the blowby system is piped up and how it works?

I've included Ferrari's illustration for the 456 which is a little clearer than their illustration for the 550 (the 575 is similar, but I think the drain line goes to the oil tank instead of to the engine)

What I'm trying to understand is:

Why are there two lines going from the blowby tank to the oil tank (A & E)? I can understand one line, which would ensure the oil tank & blowby tank are at the same pressure, but why two? (Note line A has a tee in it and one side goes to the blowby tank, and the other goes to the oil tank.)

Why is there a dedicated vacuum line (the unlabeled line at the top that runs to a tee, then splits off to the L&R manifolds) run to the blowby tank? The blowby tank is already under vacuum from the ports at the throttle bodies (lines D for both sides)?

[cribbj]

I bought a used blowby tank from eBay to look at, and possibly cut up, and as soon as I examined it, one little mystery was solved. The connections for the "A" lines on the blowby tank go straight through without stopping, ie they're nothing but a straight pipe, and the vapors don't enter the tank at all. Ferrari wanted to tie the two lines together, and to make it look clean & tidy, this was the way to do it.

So effectively both valve covers are on a common line and feed into the dry sump tank, then the line "E" comes out of the dry sump tank and feeds back into the blowby tank. Then the two "D" lines take vapors out of the blowby tank and feed them into the intake system.

Still don't know why there's a manifold vacuum line tied into the top of the blowby tank when there's already vacuum on it from the "D" lines.

[tazandjan]

John- Good stuff. If you look at the progression of Blow-By Systems from 456M to 550 to 575M to 612 you will notice the systems get simpler, and the oil drain to the engine is replaced with one to the dry-sump tank. The small vacuum lines appear to be more of a pressure equalization system than a source of vacuum, and those go to the oil filler pipe on the 612, as opposed to the vapor separator on the other three cars. The one-way valves are actually anti-siphon valves.

[cribbj]

Thanks Taz, your illustrations are much more "illustrative" than mine (from the owners manual).