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    m20 crankcase breather

    Alright guys, I just had a bad day at the dyno. Basically I fabbed up a new crankcase breather (attached to valve cover) that ran through a filter, through a 1way valve, and into the pipe before the turbo compressor. In turn, this made my car smoke a LOT of oil. Today, I took it off, and it runs like normal.

    Does anybody have a good way of making a vaccuum for the crankcase? Also, any good ways of disconnecting the breather that goes from the block to the bottom of the intake manifold (pipe, with a spring on the bottom), and making it not pressurize?

    Thanks for the help.

    matt

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    Re: m20 crankcase breather

    you sure you put that check valve in the correct way?

    that metal tube between the intake and the block is to vent crankcase gasses from the block back to the head where they can then get out. the bottom end of the motor pressurizes because of blowby. only way to stop that is to have a 100% seal on all of the rings, and even then, there would still be some pressure from the expanding oil and oil vapors.

    I vent the whole system (via the valve cover vent tube) to atmosphere. Don't even bother connecting it to vacuum. Vacuum would be better though.

    for a vacuum source, in front of the turbo works, or you could install tubes in the exhaust and create vacuum that way. either way you will need proper check valves (especially with the exhaust setup).

    -Michael McCoy

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    theo325
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    Re: m20 crankcase breather


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    Re: m20 crankcase breather

    Michael:

    I didn't get it clear what you do with crank case breater? Do you seal the hole in intake manifold and also in crank case also and only way for gases to come out is through valve cover breather?
    What I got now is while oil is thick it is getting in to exhaust. It started suddenly. So I don't know the reason why it is happening. Maybe there was to high oil preasure to turbo... hvz..J.K.jr.bad.
    BMW 527TiS '89
    BMW 316 e21 '82

  5. #5
    Michael McCoy
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    Re: m20 crankcase breather

    the breather on the valve cover is routed to a catch can, and the catch can is open to the atmosphere.

    I sealed the hole on the side of the throttle body.

    everything else is *stock*. as in I didn't change anything with the metal tube between the block and the intake manifold.

    that help clear things up? or is there something else in particular that wasn't clear?

    -Michael McCoy

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    Re: m20 crankcase breather

    Yes that's cleared up. I have something alike exept i don't have catch can. Also I need to reroute tube from head cover somewhere to the bottom as warm oil gasses getting in the saloon of the car and makes window mist.

    btw how many HP and torque are you getting? I'm right now at preasure of ~8psi getting 186whp and torque of ~315Nm. At the rear wheels.J.K.jr.bad.
    BMW 527TiS '89
    BMW 316 e21 '82

  7. #7
    Michael McCoy
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    Re: m20 crankcase breather

    those HP numbers sound a touch low... I was getting 210 hp to the rear wheels at 8psi of boost on the stock 2.5 motor. Or is this an extremely low compression motor?
    A lot has changed since that old 2.5 came out. I need to go put the car on a dyno soon.

    -Michael McCoy

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