Radiator coolant dumped from overflow tube

[Aman13]

My brother was learning to ride on my ninja, and after about 45 minutes of low speed riding the bike dumped all the coolant out from its overflow line. What are possible problems that would cause this?

[cuong-nutz]

Possible causes:

1. Leaky headgasket. Your oil could possibly be contaminated.
2. Your overflow was probably overfilled.
3. It was hot outside and there wasn't enough airflow to keep your coolant temp down. Check to make sure your radiator fins are clean and clear of debris.
4. Air in your coolant system.
5. Old coolant.
6. Wrong coolant to water Ratio.
7. Overflow line was clogged and leaking.
8. Faulty thermostat.
9. overflow cap was loose.
10. Loose hoses.

[tubarney]

is it all the coolant or is it just the coolant in the overflow?

[Aman13]

Originally Posted by cuong-nutz

Possible causes:

1. Leaky headgasket. Your oil could possibly be contaminated.
2. Your overflow was probably overfilled.
3. It was hot outside and there wasn't enough airflow to keep your coolant temp down. Check to make sure your radiator fins are clean and clear of debris.
4. Air in your coolant system.
5. Old coolant.
6. Wrong coolant to water Ratio.
7. Overflow line was clogged and leaking.
8. Faulty thermostat.
9. overflow cap was loose.
10. Loose hoses.

Thanks for the list

Originally Posted by tubarney

is it all the coolant or is it just the coolant in the overflow?

Just the coolant in the overflow tank, when I opened my radiator cap their was still plenty of coolant in it.

I checked all my tubes and lines there doesn't seem to be any lumps, cracks or weak spots. The oil in the bike is still clean and I didnt see any signs of contamination so I dont think its a blown gasket. The coolant wasnt overfilled or old because I filled it to the low point 3 months ago.

So the most probable reason is faulty thermostat?

[HKr1]

Originally Posted by cuong-nutz

Possible causes:

1. Leaky headgasket. Your oil could possibly be contaminated.
2. Your overflow was probably overfilled.
3. It was hot outside and there wasn't enough airflow to keep your coolant temp down. Check to make sure your radiator fins are clean and clear of debris.
4. Air in your coolant system.
5. Old coolant.
6. Wrong coolant to water Ratio.
7. Overflow line was clogged and leaking.
8. Faulty thermostat.
9. overflow cap was loose.
10. Loose hoses.

#5, thats when my old gpz900r took a dump

[DaBlue1]

Originally Posted by Aman13

.....So the most probable reason is faulty thermostat?

Probably not. If it was it wouldn't take 45 minutes to manifest. Idling and low speed riding for long periods can make the engine temp increase due to a lack of sufficient airflow around the engine and through the radiator. When the temp increases, the cooling fan should come on to help cool the coolant. You will also get the temp light on the dash to come on in extreme cases of overheating.

I would make sure the cooling fan works properly. Also in rare cases, the radiator cap can fail to maintain the necessary pressure (16 psi) in the radiator, which can lead to a early pressure release before it's suppose to, which looks like it's overheating.

[tubarney]

i was going to say radiator cap.

How did it come out of the over flow? Through what opening did it come out?

[r6boater]

Did/does the cooling fan kick on?

[Motofool]

Originally Posted by Aman13

....Just the coolant in the overflow tank, when I opened my radiator cap their was still plenty of coolant in it.

I checked all my tubes and lines there doesn't seem to be any lumps, cracks or weak spots. The oil in the bike is still clean and I didnt see any signs of contamination so I dont think its a blown gasket. The coolant wasnt overfilled or old because I filled it to the low point 3 months ago.

So the most probable reason is faulty thermostat?

If the expansion tank was completely empty, your coolant reached its boiling point and a steam flash blew that amount of liquid out.
Steam, which is one of the worst heat transfer media, can damage your engine very quickly, try avoiding reaching that point.

Be generous with the oil level, since your brother is using a lot of clutch and heating up the oil, while moving slowly (in those conditions the fan may not be enough for effective cooling).

http://faq.ninja250.org/wiki/Cooling_system

During practice, take breaks that allow the engine, coolant and oil to cool down some.

[Aman13]

Originally Posted by DaBlue1

I would make sure the cooling fan works properly. Also in rare cases, the radiator cap can fail to maintain the necessary pressure (16 psi) in the radiator, which can lead to a early pressure release before it's suppose to, which looks like it's overheating.

Originally Posted by r6boater

Did/does the cooling fan kick on?

I'm starting to think its my fan, I let the bike sit and idle for a while and the fan never turned on.

Originally Posted by tubarney

i was going to say radiator cap.

How did it come out of the over flow? Through what opening did it come out?

The coolant reserve tank has an overflow line at the top of the tank and it leads to the bottom of your bike basically in the center, right next to your fuel tank overflow line.