Voge DS900X coolant temperature warning: the sequence to follow

Documented in the manual rather than reported by owners. The manual treats the warning as two separate conditions, and the distinction between them decides whether the remedy is a bottle of coolant or a workshop.

What the light means

The engine is overheating. The manual states the consequence plainly: continuing to ride can damage the engine.

The sequence the manual sets out

1. Stop riding and stop the engine immediately, and leave it stopped until the warning light goes out.
2. Once the motorcycle has cooled, check the coolant level and the radiator.
3. Where the level is low, top up the expansion tank to between the LOWER and UPPER marks.

The check that identifies a system fault

The manual gives one diagnostic that settles the question on the spot:

Where the temperature warning appears while the radiator fan is not running, the fault lies in the cooling system rather than in the coolant level. That is a workshop matter and not something a top-up will address.

The fan is one of the six relays fitted to this model, alongside those for the EFI, the fuel pump, the starter, the ignition switch and the kill switch. A fan that does not run has a cause between the temperature sensor, the relay, the fuse and the motor itself, all of which are diagnosed rather than guessed at.

When the temperature climbs in traffic

Before the warning appears, the manual offers three measures for a blocked radiator or an insufficient coolant quantity:

• Reduce the load on the motorcycle, so that the engine produces less heat.
• In stationary traffic, let the engine idle. The throttle is not blipped: doing so produces more heat, not less, and at a standstill there is no airflow to remove it.
• Where neither brings the temperature down, the engine is stopped and a service point contacted.

An obstruction in front of the radiator belongs in the same category. The manual names sand and stones lodged against the matrix, and on a machine used off road that is worth a look before anything is dismantled.

Checking the level correctly

The check and any topping up are performed at the expansion tank, and the conditions matter:

• The engine is stopped and cold. Coolant expands when hot, so a hot reading is not the true level.
• The motorcycle is held upright, not on its side stand.
• The level must sit between the LOWER and UPPER marks.
• Overfilling is not permitted. Above the UPPER mark, the coolant overflows from the tube as it expands in use, which risks a burn from hot coolant.

The complete procedure is in checking and topping up coolant.

The two cases where the manual withholds the job

A completely dry expansion tank. Where the tank has emptied entirely, the manual states that it is not to be refilled by the owner. Air will have entered the cooling system and must be bled out; adding coolant without bleeding leaves an air lock, and the engine overheats again with a tank that now reads full.

A tank that needs topping up repeatedly. The manual is explicit that frequent topping up indicates a fault in the cooling system. Coolant does not evaporate from a sealed system. A level that falls is leaving somewhere, and the places it goes, a hose, the water pump seal, the radiator or the head gasket, differ enormously in what they cost to put right and in how long the motorcycle can be ridden first.

A hot system is never opened. The pressure cap holds coolant above its atmospheric boiling point, and releasing that pressure discharges it.

Related pages

The coolant replacement interval, which the plan sets at the seventh service and at two years whichever falls first, is in what Voge asks for at each service. A comparable owner report on another model is set out in 650DSX high temperature warning under acceleration.