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'77 308 Coolant Drain and Bleed

Discussion in 'Technical Q&A' started by mr308gtb, Sep 20, 2004.

  1. mr308gtb

    mr308gtb Formula Junior
    Rossa Subscribed

    Sep 12, 2004
    537
    Full Name:
    MeestahBig
    After having a small hole punctured into a coolant pipe, Ive searched the forum for a clear explanation on how to drain and bleed the coolant system. I have not been able to find one that I understand.

    1. How do I properly drain the coolant. I found the butterfly nut on the bottom of the radiator, I know this will drain some of the coolant, but seemed to me that it would leak it all over the front pans. Is this correct. Will it just drain out and dry up.

    2. How do i bleed the system. The manual is worthless. I know where the bleed screw is on the top of the radiator. But where is the bleed screw in the engine compartment. I cant seem to find.

    3. Are there any posts out there that go step by step through how to change the entire coolant system, including all parts needed, etc. Would there be any interest in starting to create an archive of detailed (to certain standards) procedures start to finish.

    Regards,
    Marc
     
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  3. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    10,525
    San Carlos, CA
    Full Name:
    Mitchell Le
    1. Yes, that is correct, it makes on hell of a big mess of fine slippery poison for small animals. You will need to drain the block as well, a cock-valve is located on block "facing the firewall" and it too will make a fine mess on you.
    2. Bleed screw in right on top of the water pump / thermostat housing. You bleed best with a hand pump.
    a. Drain and close the valves.
    b. Open both bleed screws.
    c. Fill up slowly with coolant when it looks full, attach hand pump to the overflow tank. Napa sells a kit of Coolant System Test kit, which has a fine hand pump.
    d. Pump, open it, refill, pump again until streams of coolant come shooting out the radiator bleed hole, stop, tighten the radiator bleed hole.
    e. Pump, open it, refill, pump again until the coolant shows up at the engine bleed hole, stop, tighten the screw, and refill the tank up.
    f. Fire engine, test for leaks, you are done.

    3. Check archive, this is not a new topic.
     
  4. mr308gtb

    mr308gtb Formula Junior
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    Sep 12, 2004
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    MeestahBig
    Can I reach the engine bleed hole by hand....

    Regarding the archives for the mechanically not-so-inclined folks, there are a lot of half-hearted responses that leave a lot of room for misinterpretation and error.

    I still think a forum with detailed procedures mapped from start to finish with photos and detailed descriptions, parts, etc. would be a good idea. You could even reference third party suppliers and have links to them to pay increase advertising dollars for the site.
     
  5. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    10,525
    San Carlos, CA
    Full Name:
    Mitchell Le
    Yes, you can reach the engine bleed hole by hand, you are practically staring at it when the engine cover is off. Sitting right in between the 2 timing belts.
     
  6. Doc

    Doc Formula Junior

    Sep 13, 2001
    886
    Latham, New York
    Full Name:
    Bill Van Dyne
    A respected mechanic told me to only bleed through the radiator--that that is sufficient, as long as it's done thoroughly. He also rec'd raising thr front of the car slightly, or parking on an incline, while bleeding, as the air will atomatically be forced into the upper part of the radiator.
     
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  8. Sean F.

    Sean F. F1 Rookie

    Feb 4, 2003
    3,003
    Kansas
    Full Name:
    Sean F
    Jack the front end up. Remove the sheet metal panel just behind the front spoiler. Disconnect the heater hose (~1" DIA) and allow the system to bleed from there. It does make a small mess when you first disconnect it and try to direct it into a pan, but it's much better than the other options.

    Just be sure you have a large enough container to catch all 3-gallons of coolant.

    There will still be a small amount in the engine so go ahead and drain it there as well.

    Be sure the cap in rear is off and loosen the bleed screw on the radiator itself.
     
  9. parkerfe

    parkerfe F1 World Champ

    Sep 4, 2001
    12,887
    Cumming, Georgia
    Full Name:
    Franklin E. Parker
    I highlyrecommend a power flush of the entire system at a local radiator shop. I had my ex-348 power flushed and you wouldn't believe the crap that came out. And the car only had 12k miles at the time!
     

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