Changing your Coolant on a pre-2000 BMWF650.

by Kristian #562 & Flash #412 15/10/01
Please read the
Disclaimer before attempting any work in this FAQ.
Updated 15 August, 2004 by Nate #1379


For the GS Coolant Change FAQ GS


Changing the Coolant

Recommended Coolant Interval: Every 2 Years.

Changing coolant at 600m service. This is a quote from the "Chilton Motorcycle Handbook": "One of the common misunderstandings about cooling systems is that the coolant can be ignored. You know, I can see some in the tank, so it must be fine. Well, WRONG! Coolant MUST BE CHANGED REGULARLY. It is not sufficient to just have the system full. As coolant ages, it loses its ability to resist boiling and conduct heat. But, more importantly, it also loses it anti-corrosion properties, and this will allow the build up of scale and residue in the cooling system. this build up will reduce the cooling system's ability to do its job and could eventually render the system useless. To prevent this oxidation of the aluminium cooling passages you should replace your engine coolant AT LEAST once every 2 years." from Spakur.

Reference Diagram: See the Water Pump Diagram. The item marked ‘2” is the Coolant Drain Screw. Here is a photo of the Drain Screw Location (Lower of the three Screws). 



This job is just plain easier if you remove the fuel tank. See the Gas Tank Removal Replacement FAQ. It only takes 10 or 15 minutes to remove the tank. (This task also lines up with other service items such as checking valve adjustment, re-torqueing engine fasteners and cleaning the fuel tap and tank etc.) An inmate did it without removing the tank (See Below, but even he doesn’t recommend it). If you choose not to remove the Tank, make sure you unscrew the Radiator Cap to allow the Coolant to escape without having to fight against a vacuum. Also Undo the Reservoir Tank Cap. You can JUST undo the Radiator cap by reaching under the front fairing, beneath the headlight. It’s on the RHS  of the bike, but it is a bit difficult to do up again.




 Time :



Warning.! Do this with the Bike COLD. At normal running temperature, Coolant is HOT.!

  1. Remove the Seat and the LHS Fairing.
  2. Remove the Tank. See the Gas Tank Removal Replacement FAQ for a detailed description if you’ve never done it.
  3. The Radiator will now be exposed. Remove the Radiator Cap & Clean it and the Cap Seat. This will allow you to drain the coolant without fighting against a vacuum.
  4. Remove the Reservoir Tank Cap also.
  5. On the attached Diagram remove Bolt (2), the lowest of the three bolts that hold on the Water Pump Cover. It has a copper crush washer attached to it. Have a bucket ready to collect the coolant. Put the bike onto its side-stand to get out all the coolant.
  6. I flushed out the radiator with a hose, running water through it for a while, but not under too high pressure. Clean the Reservoir Tank too.
  7. Replace the Bolt (2) and if possible use a new Crush Washer, they’re Cheap, but you can re-use the old one. Torque to Spec. (10Nm). Use Loctite 243.
  8. Fill the Radiator (1.0 liter) & Reservoir (0.2 liter) with NEW Coolant. If you didn't take the tank off you can fill the Radiator via. the Burp Tank (Reservoir), provided the Radiator Cap is Undone. Note: You have to fill the radiator SLOWLY to avoid trapping air, and give the air that does get trapped time to escape. You can help this along a bit by repeatedly squeezing the rubber hoses that go into the water pump impeller-cover area. See also Bleed Notes & Troubleshooting below.
  9. Replace the Radiator Cap.! Replace the Reservoir Cap.!
  10. Replace the Tank but NOT the Side Cover. It’s easier to check the Coolant Level with it off.
  11. Run the Engine and Check the Reservoir Level. Refill if necessary.
  12. Replace the Side Cover.

Bleed Notes & Troubleshooting:

That’s it. If you do not use Non-Silicate Coolant you MAY end up doing the water pump replacement sooner than you should. Not proven, but the GS Water Pump has failed too, it's not just a Classic problem.


From an inmate who didn’t remove his Tank:

Changed my coolant and all brake pads this weekend (1997F) and found out the following:

Coolant -

  1. You can fill the system entirely the first time by jacking the bike up to rest on the rear tire and by also bending the hose from the top of radiator to the thermostat down to allow coolant from the radiator to fill up the top of the motor. You can also massage the bubbles out of this hose. I rode for a very hot 50 miles and did not have to add a drop to the reservoir.
  2. I drained the system while on the Centerstand and carefully tipped the bike over to get everything out of the system. I did this multiple times.
  3. You can reuse the sealing washer on the drain bolt. Just torque to spec. A low range torque wrench helps here. I did use Loctite.
  4. When you disconnect and clean the remote reservoir (optional), it is a fine time to remove the helmet lock if you don’t or can’t use it.
  5. This job is just plain easier if you remove the fuel tank. It takes two minutes to remove the tank after you get the bodywork off. This task also lines up with other service items such as checking valve adjustment, re-torqueing engine fasteners and cleaning the fuel tap and tank etc.



Back Friendly Coolant Change Procedure

By Nate #1379 23/04/04

Please read the Disclaimer before attempting any work in this FAQ.


This is a method for changing coolant which can be used by individuals with back issues. Rather than having to remove the fuel tank, which is cumbersome and can be heavy if not emptied, this method involves removing the front fairing which is much lighter and can be removed and reinstalled with out any bending over.

Tools and parts needed:

1. Allen wrenches (Correct sizes in tool kit)
2. Bucket
3. Coolant (1.1 liters)
4. Thread locker
5. Crush washer for drain bolt (not required, but handy)
6. 4 rubber wellnuts (not required, but handy to have just in case)
7. Small funnel


1. Remove the seat and right side cover.

2. Remove the burp tank cap. Some people can remove the cap without removing the right side cover (I can), however, for those who can’t the right side cover is easily removed (2 allen head bolts and a plastic post in a rubber gasket hold it on)

3. Remove windscreen. On the ST, there are 4 allen head bolts which hold on the windscreen and black screen, 2 on each side.

4. Remove the 2 allen head bolts on each side holding the lower engine trim piece to the front fairing (it is silver on an ST and black on the standard F).

5. On the standard F model, there may be another allen head bolt holding the fairing onto the lower radiator bracket (not on the ST)

6. Carefully disengage the tabs on the lower engine trim pieces from the front fairing (figure 1)

7. Disconnect the headlight plug (3 prong type) by gently rocking it slightly side to side as you push it off the blades of the headlight.

8. Pull out the parking light on the lower right hand side of the head light lens (left side if you are facing the headlight)

9. Disconnect the turn indicators at their plugs (figure 2) Turning the handlebars from side to side can help give extra room to reach the plugs.

Figure 2.

10. Remove the 4 allen head bolts on each side which hold the tank cover to the front fairing.

11. Remove the final 2 larger allen bolts from the upper part of the front fairing where they bolt to the gauge bracket (figure 3)

Figure 3.

12. Carefully slide the fairing off of the tank cover. Be careful, there are tabs on the front fairing which fit into the tank cover. Set the fairing in a safe place where it cannot fall and won’t get stepped on, run over etc.

13. The radiator is now exposed. From here, the procedure is exactly the same as if you removed the gas tank.

14. Remove the radiator cap. It requires pushing down and turning counterclockwise simultaneously.

15. Remove the coolant drain plug on the water pump cover (figure 4)

16. Drain and flush. (Note: at first, the coolant will shoot out about 12 inches from the drain so place your bucket carefully). Flush until no sediment comes out of the drain hole (if you do this regularly, there may be no sediment)

17. Apply locktite to the drain bolt and replace the drain bolt with new washer (you can usually reuse the old washer, but it is good to have a new one on hand in case the old one leaks) Tighten down to spec (10 Nm).

18. Slowly fill the radiator. I find a smallish funnel with flexible hose works well to fill. If you pour slowly, you will have less chance of trapping air. Fill right up to the cap.

19. Carefully replace the radiator cap. Remember it takes pushing down and twisting clockwise to lock it in place.

20. Fill the burp tank to the full line and replace the cap.

21. Check for leaks.

22. Start bike and check for leaks again.

23. Slide front fairing back into place, carefully relocating the tabs from the tank cover into their slots in the front fairing.

24. Carefully relocate the lower engine trim tabs in their slots in the front fairing.

25. Reinstall the larger bolts in the upper part of the front fairing (figure 3)

26. Carefully reinstall the bolts on each side of the tank cover and lower engine trim (and lower radiator cover if applicable.)

27. Plug in the headlight

28. Reinstall the parking light

29. Reconnect the turn indicators

30. Reinstall the black windscreen and clear windscreen (if applicable). If the wellnuts are really old, they may not hold. In this case, you need to replace them (that’s why it’s good to have some spares on hand).

31. Test all lights.

32. Replace the right side cover (if removed) and the seat.

33. Go for a ride to the local convenience store and buy beer and pretzels

34. When you get home, check the coolant level. Top up if necessary.

35. Go inside, turn on recorded motorcycle races from Speed Channel

36. Drink beer and eat pretzels


So what Coolant Should I use ?:


Well as Flash says “Any automotive non-silicate, non-nitrite antifreeze mixed 50:50 with water is fine, and lots cheaper than BMW or Honda Juice”.

"You don't HAVE to use distilled water in a cooling system like you do in a battery. However, some will argue that you should. (Most folks are blissfully unaware that anal-retentive IS hyphenated.)"--Flash #412 (a few years later)

"Just for what it's worth (anal-retentive is probably correct, though).

Tap water conducts electricity (it is just bursting with ionic species of calcium, magnesium and chlorine, for example). Water quality varies dramatically. But if there are any significant ions present, you can generate bi-metallic corrosion (see previous threads - note that there is undoubtedly aluminum and steel, possibly copper in contact with the coolant). Distilled water is a poor conductor (ions removed), as is the stuff in the antifreeze. So bi-metallic corrosion is minimized (weaker electrolyte). Most antifreeze will have additives in it to prevent/forestall/diminish the corrosion. If you flush the coolant at the recommended intervals (even with tap water), you are unlikely to have issues (YMMV, depending on antifreeze and water quality).

Do I still have a gallon of distilled water around for batteries and such? Sure, so why not use it (I still have a few empty quart bottles of Specto pre-mixed coolant that I refill with BMW coolant as I dilute it down to operating strength). Would I use tap water in a pinch? Sure. (Clean coolant is better than dirty coolant is better than NO coolant?) "--Marty #436


However the BMW Coolant I have is NOT Silicate Free, only Nitrite Free. So look on the Bottle you are buying. They say Honda Coolant is Silicate Free. I don’t know this for a fact. If anyone CAN confirm it, Great, please send an email to the Webmaster.

Engine Ice

FWIW my experience with Engine Ice was with my Honda Hawk race bike. I read all the claims and thought it might have better heat properties than using just water (which is what's required in racing - most coolants would make the track slippery if you dumped any).

In a couple of words - it's crap. The race bike ran 20 degrees hotter with engine ice than with plain water or water with water wetter. --MarkF


Some Very Interesting Coolant Information:

Can you please confirm whether or not this product has NO SILICATES as Silicates have been blamed for failure of the Water Pump on the BMW F650 (including mine). If it does have Silicates, what percentage and how does this compare with other Brands. I would very much appreciate a prompt response as I intend to redo the Coolant this weekend.

MOTOREX (No affiliation) have confirmed this:


I wish you a pleasant motorbike season.


Arnold Zuppiger

Leiter Kundendienst


Telefon +41(0)62 919 76 91 Homepage

An:     "''" <>


What the Burp Tank is FOR

by Flash #412

The whole POINT of the burp tank (
Coolant Reservoir Tank) is to have the cooling system purged of air, for two reasons... reduced oxidation and increased efficiency. ALL burp tanks will have the hose to/from the radiator feeding (somehow) into the bottom and an overflow out the top.

My Bike Gently Weeps - Other Sources of Coolant Loss

1. Thermostat Housing

by Karl #1012

The recommended fix:

Replace the Seal between the thermostat cover and the housing. You may not need to drain the coolant, as the thermostat is fairly high, with respect to the Coolant Reservoir/Burp Tank and the Top of the radiator/head.

Marty writes:

I used Hylomar sealant on the new gasket (non-permanent, in case I DO have to take it off again to replace the head gasket).


So far, this is not a common occurrence.

2. Defective Radiator or Radiator Cap
by Kristian #562

This has not been a common reported problem on the Classic, but see the
GS FAQ for the number of defective radiators on early bikes. You can still get hole in your radiator if you get stone chip in it, ride off-road a lot, the neighbours cat sticks a pencil through it, or it's getting old and you power-wash it. You may want to consider a Radiator Guard. Refer the GS Aftermarket Frame Accessories FAQ or the Classic Aftermarket Engine Protection FAQ for Radiator Guard Options.


3. Overflow or Burp Tank Rubber Hose-line

by Werner #547 Ottawa

Crossing from Norway into Russia near Murmansk is like entering another world, the Nether World. Everything looks run down, the road, the houses, and the people. No wonder that the bike wanted to sympathize with this environment. At every stop there were a few drops of green liquid falling from the bottom of the radiator. "Chyort," three times (the Russian word for "shit"). Broken radiator? But why green, since I remember putting in orange stuff. Irish terrorists? In the evening I took off the gas tank to have a look. Relief! The little hose connecting to the auxiliary tank (overflow or burp tank) had sprung a leak right next to the stud under the filling cap. Cutting off one inch and reconnecting fixed the problem. So, next time you have your tank off, check that little hose, or replace it. Better then than when you're in the boonies.

Reattaching or Replacing Radiator Hoses

What Temperature does the Coolant Idiot Light come on at?


115 degrees which converts to 244 F



118C/245 F.



What is the Radiator Cap Release Pressure


Todd #389 & Alberta Deryl

GS/GS Dakar


Radiator Cap Comparisons GS vs. Classic

If you're looking for a Replacement Radiator Cap:


These guys make Radiator Caps:

This one looks small and is 1.2 bars

Radiator Manufacturers.

General Comments on Cooling System Maintenance

Riding with NO coolant! What have I done?

Aftermarket Oil Cooler?

FWIW, Chrysalis Racing apparently used a Goodridge oil cooler on their modified Rotax-powered bike in 1999.