Why is my coolant level low again and again. I drive for only 30 kms; after that the coolant is below minimum level. I top it up to the maximum level.

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    Welcome to the site. You have not told us much about the bike. How many miles are on the engine? Have you had recent maintenance done? Is there smoke or steam coming from the exhaust pipe? If so, what color is the smoke? Please use the edit feature to add details and maybe we can offer specific answers.
    – CharlieRB
    Nov 16, 2017 at 12:42

2 Answers 2


As the engine runs, it circulates the coolant. The coolant will also expand and contract with the heat cycles of the engine. As the coolant expands, any air in the system will eventually be forced out into the reservoir and bubble to the top. As the coolant cools and contracts, a small amount of coolant from the bottom of the reservoir will be sucked into the engine.

If the coolant was just changed, or this is a new bike, there could still be air in the system. This is normal, and over time the air will be expelled, it will be replaced with coolant, and the level in the reservoir will go down.

If this is a long term problem, it means the coolant is disappearing. The most obvious and simple reason for this is there is a leak somewhere. If you can, try parking the bike and a flat, dry cement pad out of the sun. It will be easier to identify leaks, as they'll leave drips or pools under you bike. Cleaning the bike helps as well, since you can more easily spot liquids on the outside of the engine.

The worst case scenario is that you're burning coolant as part of the combustion process. Telltale signs of this would be white smoke in the exhaust, a "sweet" smell from the exhaust, and a tendency for the bike to overheat.

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    The liquids used in vehicle cooling systems have a very small cubical coefficient of expansion so the change in level due to change in temperature is very small - if a large change in level is evident then air is probably in the system...
    – Solar Mike
    Nov 16, 2017 at 9:05

I also own a Dominar and have seen this issue in lot of other dominars. This issue can happen due to many reason. the bike might have a factory fault which might be draining the coolant.

coolant can also come out of reservoir if heated instantaneously, as experienced in "Mumbaiker Nikhil's" bike too. Due to sudden change in heat from a cold start, whole coolant expands more than capacity and starts spilling. This might have happened at the moment you were driving. Thus went unnoticed.

Although new Dominars are seen using too much coolant in the break-in time.

I will suggest going to service center and getting checked any seepage in the radiator assembly or the coolant reservoir and pipes.

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