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Vacuum bleeder?

Discussion in 'EEK! - Every Extended-K Car' started by Jacks 400, Jan 14, 2020.

  1. Jacks 400

    Jacks 400 Member

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    First, I would like to thank everyone who has helped me to solve previous dilemmas with this car. Here's another one where I'm a little stuck.

    1983 Dodge 400, 2.2. Here's the vacuum diagram.

    [​IMG]

    I don't have the part on the right-middle labeled BLEED. On my hood diagram, it's labeled Filtered Air Bleed.

    If I understand the system, the CCEV coolant switch sends vacuum to the Air Switch Relief Valve when the engine is cold. When it warms up, the switch closes and this Air Bleed is supposed to restore air pressure. I'm not sure how it does that, I'm guessing it's either some sort of orifice or needle valve.

    Does anyone know what it is and where I can get one?

    Thanks in advance.
     
  2. ImperialCrown

    ImperialCrown Moderator
    Level III Supporter

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    It was spliced in-line into the hose, unless someone replaced the hose and didn't transfer the bleed?
    Google for Mopar 3870649.
     
  3. AllanC

    AllanC Well-Known Member

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    In the 1980s with carbureted engines the air pump directed air towards the exhaust manifold at engine startup. With a cold engine and with an oxygen sensor that has not reached operating temperature and EGR not enabled, having excess air present in the exhaust manifold helped to oxidize unburned hydrocarbons. As the engine starts to warm up and the oxygen sensor starts to function and the catalytic converter reaches operating temperature, air was directed AWAY from the exhaust manifold. Directing air at the exhaust manifold would interfere with proper operation of the oxygen sensor and catalytic converter. Also it would raise exhaust temperatures at the engine valves and cause an increase in NOX emissions.

    See the attached image for a typical vacuum diagram for the air switching valve. The bleed orifice was just a plastic tee with the tee end sealed and drilled with a small opening. When the engine is cold and vacuum is applied to the air switching valve, 18 - 20 inches of vacuum generated in the vacuum line is more than sufficient to overcome this small vacuum leak. The vacuum signal causes the spring loaded switching valve to direct air flow to the exhaust manifold. When the engine reaches a certain operating temperature, the thermal vacuum control on the thermostat housing closes and stops the vacuum signal to this air switching valve. With the vacuum line sealed, there has to be a way to bleed the vacuum from this line so the spring in the switching valve can cause the air flow to be directed to the downstream port in a timely fashion. This orifice bleed provides that capability.

    Dodge 600 1983 2_2 liter air pump.gif

    You might check for proper operation of the air switching valve. Are you thinking you need this bleed orifice in the line to pass a state / municipality emission check? I would tend to think that if you have to pass tailpipe emission standards, the engine would be tested at full operating temperature. This air switching valve only functions during engine warm up and is not used once the engine reaches operating temperature. Maybe you can delete it???
     
    Jacks 400 likes this.
  4. Jacks 400

    Jacks 400 Member

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    Thanks for the part number. I couldn't locate one on a quick google search, but I'll keep trying.
     
  5. Jacks 400

    Jacks 400 Member

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    That's pretty much what I figured. This morning I teed in a vacuum gage and started the engine. Vacuum read 15". I let it warm up and the vacuum stayed the same. I bled the vacuum and it went to zero. So I definitely need to do something.

    I'm kind of obsessive about "If it's there, I want it to work the way it was designed" when it comes to this sort of thing. Even though I don't have to worry about emissions tests, I don't want to delete it.

    Knowing that it's just an orifice, I may try to make something if I can't find the right part. Maybe experiment with a vacuum hose connector with a small pinhole in it until I get something that functions correctly.

    Thanks for the info. :)
     

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