Replacing radiator fluid in 2001 Civic

Discussion in 'Civic' started by martin lynch, Oct 12, 2008.

  1. martin lynch

    martin lynch Guest

    I have a 2001 Honda Civic and need to drain and fill my radiator. I
    have read some tutorials but have a few questions:

    1) Some have advised draining the radiator, then filling with
    distilled water and running for a while, then draining the water and
    filling with coolant. However, if I put water in, won't that get
    circulated into the engine block? If so, when I refill the radiator
    with my pre-mixed 50/50 coolant (comes this way from Honda), then my
    coolant in the system will be super diluted as it mixes with the water
    I introduced into the engine block. Am I missing something here?

    2) If the car has a bleeder valve (not sure if it does, I'll have to
    check), how does it work? Do I simply open the valve while filling the
    radiator while the car is off? Or do I fill the radiator, close the
    radiator cap, then open the valve while the engine is running?

    3) If I do the bleeding method where I open the cap and run the
    engine, do I simply observe the fluid in the radiator while the engine
    is heating up, and pour coolant in as the level drops, WHILE THE
    ENGINE IS RUNNING? At what point do I need to worry that the coolant
    will get so hot that steam blows my head off? Or does this not happen
    since I'm running the engine with the cap off, preventing a pressure
    martin lynch, Oct 12, 2008
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  2. martin lynch

    jim beam Guest

    no, you're correct. i wouldn't call it "super diluted" but it's
    definitely weaker than normal. you can top up with undiluted antifreeze
    to get the right mix if this worries you.

    the latter.
    fill as much as you can with the engine off. squeezing the bottom hose
    helps a lot. then run and bleed air with the valve - if you have one.
    if not, simply overfill the expansion bottle, run, then let cool
    overnight. contraction on cooling will suck the fluid you need back
    into the radiator, provided you have no air leaks.

    other tips on effective drain include unscrewing the plug on the block
    to let all that fluid out too, and keeping the cabin heater valve open
    so that drains as much as possible also.
    jim beam, Oct 12, 2008
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  3. martin lynch

    Elle Guest

    Do you have an owner's manual? Follow its steps exactly and
    you will be fine. Post back if you want a site that has free
    online owner's manual.
    Like Jim said, you are correct. With a lot of study of the
    owner's manual coolant capacities commentary, one can figure
    out how to mix the anti-freeze to make up for the diluted

    On the other hand, it is not a big deal to skip your
    proposed flush, let a little old coolant stay in the engine
    block, and add new coolant.

    Coolant chemistry has come a long way. As long as you follow
    the maintenance schedule for changing coolant, all will be
    Your Civic does not have a bleeder valve. The procedure uses
    the simple "burp" approach to purge air from the cooling
    system via the top of the radiator (when filling) and via
    the top of the radiator and out the reserve tank during

    Use Honda OEM coolant. Or you can try orange Havoline.
    Orange Havoline comes both pre-mixed and undiluted. A few of
    us here have been using the orange havoline for years and
    are quite happy with it.

    Remember there is a difference between the radiator drain
    plug and the engine drain bolt. Both are going to come off
    to properly drain the system. Do get a new washer for the
    engine drain bolt. Buy non-hardening sealant (per the
    directions in the owner's manual). Permatex makes such a
    sealant and it specifically says it is good for the cooling
    system. You can get it at Autozone.

    One of the most important steps for ensuring a good purge of
    air is making sure the radiator fan comes on twice. This may
    take 40 minutes or more of the car idling, so have a
    magazine and chair.

    Correct, no pressure buildup with the cap off. Steam from an
    open container is not going to exert any meaningful
    pressure. Perhaps you are thinking of how some foolish
    people take off the radiator cap /after/ the system is hot
    and pressurized. Then a mixture of hot coolant and steam
    will blow the cap off and create a dangerous momentary
    gusher as the person removes it.
    Elle, Oct 12, 2008
  4. martin lynch

    jim beam Guest

    yes. make sure it's NOT the silicone sealant. most auto shops have
    tons and tons of silicone sealants, and just one non-silicone. easy to
    get confused.
    jim beam, Oct 12, 2008
  5. martin lynch

    Tegger Guest

    You MUST drain the block as well as the rad. The block has its own drain

    DO NOT just drain the rad. DO NOT fill the system with water and run it.

    With block and rad drains open, run water from garden hose into rad
    until drains run clear. Allow water to drain, then close drains.

    If you need to capture /all/ flush water, open block drain only, place
    large container on ground. Feed water in thru rad neck. When block drain
    runs clear, allow it to empty, but leave open. Move catch container.
    Open rad drain. More water thru rad neck until rad runs clear. Now close
    both drains. Don't feed water thru rad too hard during this step, or
    else it will come out thru block drain as well.

    No bleeder valve. Fill system thru rad filler neck. Leave cap off. Start
    engine. "Burp" upper rad hose to help free bubbles. Add as needed thru
    rad neck until the level no longer drops but rises and begins to spill
    out of neck. Put cap back. Make sure reservoir is filled to MAX. Allow
    car to idle until rad fan comes on twice (WATCH DASHBOARD GAUGE!). Shut
    engine off and allow to cool fully (two hrs or more) . Add coolant to
    reservoir back to MAX mark. Check rad to make certain level is still up
    to top with no air present. Watch reservoir level after next few drives.
    Add as necessary until it stops dropping.

    See above.
    Tegger, Oct 14, 2008
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