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.

    6 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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  3. Total Comments 6


  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: 7,095, Level: 58

    Oct 2007
    47 / 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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  7. #4
    Points: 4,597, Level: 46

    Jul 2011
    5 Days Ago
    50 / 0 / 0 / 0
    Posting a comment from advrider with coolant flush for F800GS that helped me when refilling the coolant.
    Had issues with overpressure (air in the system) i tried different techniques (tilting bike, the bmw manual with air bleeding screw) and this was the only thing that helped me out:

    (some modifications made in the post)

    // user: JoelWisman
    "The factory method does not always work for getting the air out of the cooling system and the bike does not self bleed at all.

    After 2 service bulletins describing different methods of bleeding, BMW finally said "too hell with it" and made a special tool to do the job that costs a tunn.

    We now have that special tool, but before we got it, I came up with a method that has always worked for me.

    1: Slowly fill the system from the radiator till it is full to the tippy top.
    1.5 Tilt the bike from side to side to get air out of system. Do this 4-5 times at each side.
    Squeze the coolant hoses (soft hoses) 2-3 times to pressure out air. Be carefull so coolant dont overleak from the radiator, refill slowly if needed.

    2: Open air bleed screw pictured in post above till air stops coming out, then retighten.

    3: Fill radiator back to the tippy top and replace radiator cap.

    4: Start bike and idle for a few minutes, open bleed screw for a few seconds untill the coolant is bubblefree and retighten.

    5: Rev engine to 4,000 rpm or so and rock/tilt bike slowly from side to side with rpms high, then hold straight or center stand and open air bleed screw for a few more seconds (coolant will be HOT, don't remove your dermis).

    6: Shut off bike and allow to cool down (at least 30 minutes, carefully open radiator cap and fill to tippy top, replace radiator cap. Be sure that the cap is not hot and this also includes

    7: Start bike and allow to idle till cooling fan comes on.

    GOOD: If it took a long time for the fan to come on, the whole radiator is too hot to continuesly touch from behind, and the fan is blowing off a lot of heat, go ride, everything is working!

    BAD: If the cooling fan comes on pretty quick, the back of the radiator is not to hot to continuesly touch everywhere, and the fan is not blowing off a lot of hot air but rather just warm air from the hot motor and exaust surfaces, you failed, repeat steps above.

    Once the system acts normally, fill the catch tank to the maximum line while the bike is hot and cooling fan is cycling on and off. Go for a few rides allowing the bike to cool completely between and check that coolant in the catch tank has remained above the minimum line.

    Congradulations, you've just bled the air out of a cooling system that is sometimes a bitch to do so "
    Another check if the system is ok is to check the coolant temp in the onboard computer display, it should not go over the middle level in the display

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  9. #5
    sooty60's Avatar
    Points: 1,791, Level: 25

    Real Name
    Newcastle, NSW
    Jan 2015
    6 / 0 / 0 / 0
    '14 F700GS
    With the above posts in mind, I recently changed my coolant and devised a static method of bleeding the system with the bike in a cold state.
    I bought a generic radiator cap ( must be double seal type for use with expansion tanks) from a general motor parts store and removed all the components and reinstalled only the outer seal, using a bolt sealed with silicon.
    This allows the system to be sealed except for the outlet to the expansion tank.
    With the bike on the side stand or supported in a lower position, fill the expansion tank with mixed coolant (50/50)
    Crack the bleed bolt on the water pump, allow air to escape and when air free retighten, reinstall normal radiator cap and adjust normal level in expansion tank.
    Wash the motor to remove any bled coolant.
    Check when hot as in above posts.
    Last edited by sooty60; 04-03-17 at 01:03 AM. Reason: non essential information

  10. #6
    Runmyownlife's Avatar
    Points: 1,325, Level: 21

    Real Name
    Calgary, Alberta
    Feb 2017
    2 Hours Ago
    58 / 0 / 0 / 0
    '08 F800 ST
    My first post!
    Regarding the o ring connecting the coolant pipe to the heat exchanger, I researched the size, material and online sources. In brief, 12mm id, 2.5mm cross section, 17mm od. Nitrile (aka Buna-N) is good for -40F to +250F and Ethylene glycol base fluids.

    8 cents plus shipping! (USD $10, one week shipping to Canada. About half that cost for the USA.)

    Here's the source material:

    Heat Exchanger/Leads O-Ring
    BMW OEM Part 11117694729

    Sized via:

    12mm id
    2.5 width (cross section)
    (2 x cs) + id = od
    od = 17
    2.5mm X 12mm Metric Buna-N 70 O-Ring

    Buna-N / Nitrile Recommended uses:

    General purpose sealing.
    Petroleum oils and fluids.
    Hydraulic fluids
    L.P. gases
    Cold Water.
    Silicone greases and oils
    Di-ester base lubricants (MIL-L-7808).
    Ethylene glycol base fluids (Hydrolubes)

    Nitrile is not recommended for:

    Halogenated hydrocarbons (carbon tetrachloride, trichloroethylene)
    Nitro hydrocarbons (nitrobenzene, aniline)
    Phosphate ester hydraulic fluids (Skydrol, Fyrquel, Pydraul).
    Ketones (MEK, acetone)
    Sunlight, UV
    Strong Acids Ozone
    Automotive brake fluid

    The most commonly used elastomer for sealing products. Nitrile, also known as Buna-N or NBR,
    is a copolymer of Butadiene and Acrylonitirle. It has a temperature range of -40F to +250F and
    is exceptionally resistant to petroleum base oils and hydrocarbon fuels. Nitrile materials also
    exhibit excellent tensile strength and abrasion resistance properties. The material performs
    well with most dilute acids, silicone oils and lubricants and in water applications.

    It is not recommended for use with ketones, aromatic hydrocarbons and
    phosphate ester hydraulic fluids.
    F800ST - 2008
    My Garage

  11. #7
    rx35285's Avatar
    Points: 9,947, Level: 68

    Real Name
    Cedar Falls, IA, USA.
    Nov 2007
    6 Days Ago
    480 / 1 / 123 / 48
    '92 K75S
    '08 F800ST
    '14 F700GS
    The coolant pipe o-ring is available for $1.72 from Communications are top notch. Shipping is prompt and free in the U.S., and they will ship to Canada. Don't know about other international destinations. I have no connection with A&S other than being a very satisfied customer.


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