Coolant flush and replacement. - BMW F800 Riders Forum & Registry

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  1. Joined
    Jan 2009
    New Orleans, LA

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    Coolant flush and replacement.

    2 Comments by CB-800S Published on 06-21-09 04:54 PM
    So. I'm gearing up for a track day where regular, anti freeze coolant is verboten. My options are -

    Drain the anti freeze and run distilled water at the track then replace the anti freeze.

    Drain the anti freeze and run a track specific coolant such as Water Wetter and water then replace the anti freeze.

    Drain the anti freeze and run Engine Ice coolant that is track legal and good for every day use and leave it in there.

    I went with the Engine Ice coolant option because I can leave it in there and it'll work for track and everyday riding.

    Draining the cooling system went like this-

    Remove the black center panel from the faux gas tank, the right lower fairing, the right upper fairing and by necessity, the mirror and the indicator.

    Unscrew the water line that runs to the heat exchanger (the lower pipe).

    Let the coolant drain out then unscrew the radiator cap and the expansion tank cap and let that drain. Next unscrew the engine drain screw and let that drain.

    At this point I poured water down the expansion tank and let it run out of the water line that runs into the heat exchanger then plugged this line with my finger and poured water down the expansion chamber and let it run out of the engine drain point.

    After that I replaced the engine drain screw (has a copper washer that should be renewed) and replaced the water hose that runs into the heat exchanger (has an O ring washer that should be renewed). Next I loosened the air bleed screw -

    then filled up the radiator with water until it ran cleanly from the air bleed point. I tightened the air bleed screw, filled the radiator to an inch below the neck and put the cap on, filled the expansion tank to halfway between the Low and High markers, put the cap back on then started the engine and let it run for 10 minutes or so until the fan behind the radiator came on.

    At this point I turned off the engine, let it cool then repeated the whole process re filling the coolant system with Engine Ice.

    Worthy of note - the manual says to clamp the hose from the expansion tank to the radiator before unscrewing the radiator cap -

    I did this the first time but couldn't for the life of me think why. Maybe it stops the contents of the expansion tanks overflowing the radiator before the radiator has drained - whatever, the shit went everywhere anyway and the second time I drained I didn't bother with the clamp and nothing gushed out over the radiator.

    I didn't renew the copper washer on the engine drain bolt or the O ring washer on the coolant line into the heat exchanger. Mostly because I'm a rank amateur mechanic and forgot to buy said replaceable items so decided I didn't need them. I would definitely do this next time - if I lose sleep worrying about it I may re drain and refill with new washers.

    I don't own a torque wrench so I never torqued my nuts to the specific Newton Meter (10 Nm for both the engine drain plug and the line to the heat exchanger). Torque wrenches run from $20.00 -$2,000. I figure if the twenty dollar wrench was accurate then they wouldn't make a two thousand dollar one. I am also willing to bet my good hand tight interpretation of 10Nm is as close as a twenty dollar torque wrench.

    Oh yes, after filling, run to normal operating temperature, turn off, let cool, check level at the expansion tank. Popular opinion is that filling to the High mark causes coolant overflow and so filling somewhere closer to the Low mark is desirable. Mine ran for 3,000 miles at the High mark and never overflowed so I don't know what to tell you. I refilled halfway between High and Low marks on the Expansion tank.

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  4. #2
    CB-800S's Avatar
    Real Name
    New Orleans, LA
    Jan 2009
    348 / 0 / 110 / 70
    Photo's for above post -

    1) The lower pipe to the heat exchanger.

    2) The engine drain screw.

    3) The air bleed screw.

    4) The radiator hose clamped with a G Clamp - there's no point to this photo so screw it.

  5. #3
    Antman's Avatar
    Points: 5,552, Level: 51

    Oct 2007
    46 / 0 / 4 / 4
    '08 F800ST
    "The lower pipe to the heat exchanger."
    Charles, Without your help I don't know if I could
    have figured out where to drain the coolant.
    My K100 and K1100 I had for seven years each,
    both had easy to find drains.
    The vent plug and the block drains would have been
    equally difficult to locate without your help.
    It went time it will be a breeze.


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