Crankcase/cambox ventilation

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andy wright
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Crankcase/cambox ventilation

Post by andy wright » November 2nd, 2010, 8:17 pm

Evening Guy,
A tedious question which I am having difficulty in answering. My two A4 files of the Lancia factory manual do not appear to help much. The Integrale crankcase ventilation seems to operate as follows. Fumes from the upper cylinder are vented to a sealed tank via a pipe from one end of the cambox. Crankcase fumes also pass to this tank via another pipe. A third pipe connects this tank to another outlet(or inlet?) on the crankcase via a flame trap. There is also a connection, via a one way valve , from this pipe to the inlet manifold. So it looks as if any separated oil drains back to the lower part of the crankcase and fumes to the inlet manifold.
So, the questions are;
(a) Am I on the right lines and
(b) if I want to replace this system with a catch tank, apart from blanking off the inlet manifold take-off point, any advice on how to pipe this little lot up, bearing in mind that commercially available catch tanks seem to be born with just two pipe connections.
Andy
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WhizzMan
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Re: Crankcase/cambox ventilation

Post by WhizzMan » November 3rd, 2010, 9:24 am

I would be careful with removing carter ventilation from the inlet. Having the intake suck out air is good for preventing sludge and it will help reduce oil usage. Even the minute pressure difference will keep the piston rings sucked to the cylinder wall a lot better when on the up stroke. Your engine is designed with this pressure in mind. If you are worried about contaminating your inlet air, I'd put a better separation box in between, but keep the ventilation connected.
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Guy Croft
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Re: Crankcase/cambox ventilation

Post by Guy Croft » November 3rd, 2010, 11:46 am

Because the head is connected to the block via the oil drain-down ports the gas in the cambox region and crankcase is at the same pressure and it doesn't matter overmuch where you vent it from. Naturally the amount of gas coming out depends on the blow-by past the piston rings and one would not want to restrict it - opening up the crankcase breather pipe (arrowed - see photo) and putting your hand over it will soon tell you how 'gassy' your motor is.

If you want to run a catchtank - no problem, just hook it up to the crankcase breather and blank off the one on the head. OE breathers can look very complicated, but if you're running a catchtank you can bin most of the system.

Just be sure to mount the tank above the level of the crankcase breather to allow condensed oil vapor to run back, otherwise it could fill up the tank.
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16v crankcase breather.JPG
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andy wright
Posts: 38
Joined: September 6th, 2010, 5:43 pm
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Re: Crankcase/cambox ventilation

Post by andy wright » November 3rd, 2010, 7:58 pm

Evening Guy,
Thank you very much for that reply. Very helpful. Now I know what to do. I already have a location for the catch-tank which is high up in the engine bay.
Andy
GC_20

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