DS900X Coolant Change & Cooling System Bleed

The DS900X cooling system is a sealed pressurized loop with a small expansion (sub) tank, a single-speed cooling fan, and a thermostat that opens between 83 and 87 degrees C. Total fluid capacity is just under 2 litres. Per the official service schedule, coolant is replaced every 2 years regardless of mileage, and at the 30,000 km major service interval.

The job takes about 60 minutes including the air-bleed cycle. Less if you’ve done it on other bikes; more if you’ve never bled a sealed cooling system before.

Specifications at a glance

Item	Value
Coolant grade	GLYSANTIN G48-24
Mix ratio	1:1 with distilled water (50/50)
Coolant capacity (radiator + engine)	1.5 L
Coolant capacity (sub tank / expansion bottle)	0.38 L
Total system fill	~1.88 L
Service interval	Every 2 years, or at the 30,000 km major service
Radiator cap relief pressure	120 to 150 kPa
Thermostat opening temperature	83 to 87 deg C
Thermostat fully open	95 deg C
Water pump drain bolt torque	6 N.m (replace flat washer)
Thermostat cover bolt torque	10 N.m

The GLYSANTIN G48-24 specification matters. Voge’s manual is explicit: do not substitute silicate-based coolants, because the silicate accelerates water pump seal wear and can block the radiator passages. G48 is a hybrid OAT (organic acid technology) coolant that’s compatible with the seals and aluminium components used in this engine. Most BMW/VW shops carry it; aftermarket equivalents are fine if the spec sheet matches G48.

Never use tap water for the dilution. The minerals in tap water cause scale buildup in the radiator over time. Distilled water is widely available at supermarkets and pharmacies.

What you need

• 2 L of GLYSANTIN G48-24 concentrate (some products come pre-mixed; if so, you need 2 L of pre-mixed)
• 1 L of distilled water (only if you bought concentrate)
• One new copper / aluminium flat washer for the water pump drain bolt (Voge specifies replacement)
• 8 mm or 10 mm socket for the water pump drain bolt (depends on production batch)
• Phillips screwdriver for the right windshield decorative component
• Drain pan (3 L+ capacity)
• Funnel
• Paper towels and rags
• Coolant disposal container

Critical safety check before starting

The engine and radiator must be completely cold. Touch the radiator cap with the back of your hand, then with your fingertip; if you feel any warmth at all, walk away and try again later. Hot coolant under pressure will eject through the cap opening and cause serious burns. The official Voge warning: “the coolant may inject or splash out and get [you] injured.”

Don’t trust the temperature gauge on the dash. After the bike has been parked, the gauge can read low even when the upper radiator hose is still hot. Touch the parts.

Procedure

1. Park and prep

Park on level ground. Open the main stand (centre stand). Engine cold.

Remove the right windshield decorative component of the fuel tank using the Phillips screws that hold it. This exposes the radiator cap.

2. Remove the radiator cap

Slowly turn the radiator cap counter-clockwise. If you feel any pressure releasing (hissing), STOP and let it cool further before continuing. A genuinely cold system will release no pressure when the cap comes off.

Set the cap aside on a clean rag.

3. Drain via the water pump bolt

Locate the water pump drain bolt on the underside of the water pump housing. It has a flat washer underneath. Place the drain pan beneath it.

Loosen and remove the bolt. Coolant will flow out steadily for a few minutes. Don’t lose the flat washer; you’re replacing it but you want to confirm what size the new one needs to match.

Once the flow has fully stopped, install a new flat washer and refit the drain bolt. Torque to 6 N.m. This is a small bolt - over-torquing strips the threads in the aluminium water pump body.

4. Drain the sub tank (expansion bottle)

The expansion / storage tank holds 0.38 L that doesn’t drain via the radiator alone. To empty it:

• Locate the siphon hose running from the heat radiator to the storage tank.
• Disconnect the hose at the radiator end (it’s held by a clamp; pinch and slide).
• Pull the disconnected hose end down below the engine, into the drain pan.
• The expansion tank drains by gravity through this hose.

Once empty, rinse the inside of the storage tank with clean (distilled) water and pour out. This flushes any old contaminated coolant residue.

Reconnect the siphon hose to the radiator with its clamp. Make sure the clamp is fully seated.

5. Mix the new coolant (if using concentrate)

Pour 1 L of GLYSANTIN G48-24 concentrate into a clean container. Add 1 L of distilled water. Stir gently to mix. You now have 2 L of 50/50 mix, which is enough to fill the system and have a small amount left for top-ups.

If your product is already pre-mixed, skip this step.

6. Refill via the radiator filler neck

Using a funnel, pour the 50/50 mix into the radiator filler neck slowly. The system will accept the first ~1.3 L easily. Stop when the level reaches the bottom of the filler neck.

Don’t install the cap yet. The system contains air pockets that need to be purged before sealing.

7. Bleed the system (the step many people skip)

This is what makes the difference between a good coolant change and a system that overheats two weeks later because trapped air kept the thermostat from sensing real coolant temperature.

The Voge procedure is:

1. Shift to neutral. Confirm with the dash.
2. Start the engine. Let it idle for 2 to 3 minutes. Watch the radiator filler neck - you’ll see bubbles rising as air works its way out. The coolant level will drop as air is displaced.
3. Snap the throttle 3 to 4 times. Just blip it - rev to maybe 3,000 to 4,000 rpm and let off. Each snap forces a slug of coolant through the system and helps dislodge trapped air pockets.
4. Stop the engine. Wait a moment.
5. Top up the radiator to the bottom of the filler neck if the level dropped during bleeding. It usually does.
6. Refit the radiator cap. Hand-tight, then a quarter turn with the cap tool / by hand. Don’t over-tighten.

8. Fill the sub tank

Locate the expansion / storage tank. Fill with 50/50 coolant mix to the MAX line. The sub tank has visible level marks; fill to the upper line, not above.

9. Verify after a real warm-up

Take the bike for a 10 to 15 minute ride that gets the engine to full operating temperature (you’ll see the cooling fan kick in at least once). Park, let it cool fully (overnight is safest), and check the radiator level.

If it’s dropped (it usually does as residual air finds its way out), top up with 50/50 mix. The expansion tank should also still be at MAX; top up that too if needed.

A second top-up after the first proper warm-up cycle is normal and not a sign of any problem. If you find yourself needing to top up repeatedly over weeks, that’s a sign of a leak (head gasket, water pump seal, or hose) and you need to investigate.

10. Reassemble cosmetics

Refit the right windshield decorative component with its Phillips screws.

11. Reset the service indicator

If the coolant change coincided with a major-service mileage, the dashboard’s service-due reminder needs to be cleared manually. See the DS900X service indicator reset guide for the 3-button procedure.

12. Disposal

Used coolant is toxic to humans, pets, and wildlife. Pour into a sealed container and take it to a hazardous waste drop-off. Most municipal recycling centres accept used antifreeze for free. Never pour coolant down a storm drain or onto the ground.

Common pitfalls

• Skipping the bleed. Trapped air keeps the thermostat from opening at the right time, and creates hot spots that can damage the head gasket. The 2-3 minute idle plus throttle snaps is non-negotiable.
• Tap water dilution. Mineral scale builds up over years and reduces cooling efficiency. Distilled is cheap; just use it.
• Wrong coolant. Silicate-based “universal” coolants in green or pink will react badly with this engine’s seal materials. G48 spec or compatible is the rule.
• Reusing the water pump drain washer. Voge specifies replacement. The old washer has compressed and won’t seal as well; you’ll get a slow weep.
• Over-torquing the drain bolt. 6 N.m is finger-tight plus a touch with a torque wrench. The water pump body is aluminium and the threads strip with surprisingly little extra force.
• Forgetting to fill the sub tank. The radiator level alone doesn’t tell you the expansion bottle is full. If the bike runs hot after a coolant change, the first thing to check is whether the sub tank is at MAX.
• Refitting the radiator cap before bleeding. The system has to be open to the atmosphere during the bleed cycle. If you cap it, the air can’t escape.

Cross-reference

• This is the same KEL895 / LX286MX engine as in the BMW F900 GS / R / XR. The cooling system architecture and capacities are essentially identical (slight differences in radiator surface area between the bikes, but the loop is the same). The G48 coolant spec is shared between Voge and BMW; if you have a BMW shop nearby they’ll have the right product on hand.
• The thermostat (initial 83 deg C, full open 95 deg C) is also shared. Replacement P/N is documented in the DS900X chassis service manual.

Sources

• Voge DS900X Engine Service Manual (English) - pages 25 to 31 cover the cooling system specifications, troubleshooting, and replacement procedure. This guide reorganises and condenses those pages into an owner-friendly form.
• Voge DS900X Owner’s Manual (English) - service interval table confirms the 2-year replacement cadence.
• DS900X torque specifications - cross-reference for water pump and thermostat cover torques.

If you’ve found a useful tip we missed (e.g. a drain bolt access trick, a cleaner alternative to the OEM siphon hose disconnect), send it in and we’ll fold it into the guide.