Radiator bleed procedure?

Discussion in 'Technical Q&A' started by Dla, Mar 18, 2004.

  1. Dla

    Dla Karting
    Silver Subscribed

    Nov 10, 2003
    Atlanta GA
    Full Name:
    Lee Anderson
    I have a 88 328 and am in the process of reconnecting one of the heater cores. I have read several suggestions on the best way to 'bleed' the cooling system once I reconnect the heater core.
    Could anyone elaborate on the most efficient way? Can i just use the radiator bleed valve with the cap on the coolent tank and the heaters on, or do you suggest the thermostate 10 mm bleed as well?
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  3. groovzilla

    groovzilla Karting

    Nov 28, 2003
    seattle, wa.
    Full Name:
    eliminate having to unscrew and possibly loose or get burnt with hot coolant by removing the 10mm thermostate bolt..

    check the posts from a few days ago regarding this...

    good luck..
  4. yelcab

    yelcab F1 World Champ

    Nov 29, 2001
    San Carlos, CA
    Full Name:
    Mitchell Le
    I used a pump from a radiator pressure test kit.

    1. Open the radiator bleeder screw, pump it until the coolant come out.
    2. Refill, close radiator bleed screw, pump it until it comes out the screw on to of the thermostat housing.
    3. Stop, tighten the screw, you are done.

    THe engine was never cranked on.
  5. DGS

    DGS Four Time F1 World Champ
    Rossa Subscribed

    May 27, 2003
    Full Name:
    I've also had good results with a "pressure bleed", as described by yelcab, above.

    But one caveat: Be sure you have the heater controls "open" (full hot), or you'll leave air trapped in the heater core.

    If you do the bleed cold, right after reassembly, you may need to repeat after the engine runs a bit, so the coolent flow can shake out any air bubbles lingering in the system.

    If you don't happen to have a radiator tester, you can improvise a bit. The cooling system doesn't take a whole lot of pressure. I've managed with a hand cranked air pump, a plastic bag, and a few rubber bands. ;)
  6. Mike C

    Mike C F1 Veteran
    Lifetime Rossa Owner

    Aug 3, 2002
    Southeast USA
    Full Name:
    Mike Charness
    It's not my area of expertise, but wouldn't the thermostat being closed keep the coolant (or air) from properly flowing to the front radiator?
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  8. yelcab

    yelcab F1 World Champ

    Nov 29, 2001
    San Carlos, CA
    Full Name:
    Mitchell Le
    You are supposed to drill a 1/16 inch hole into the side frame of the thermostat before installation just for this purpose, you do know that, right?

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