Hey all

  I noticed a couple weeks ago a slow coolant leak from the overflow tube on my CBR 250. It got worse, I filled the reservoir and within a few days it was empty again I just filled it with water and it just pissed it out dry, the bike is cold, haven't ridden since yesterday. My mechanic said he thought it was a blown head gasket but why would that affect the coolant from the reservoir, on a cold nonrunning bike. Obviously, I am ignorant of the cooling system but does anyone have any opinions on this before I let him operate?  Also, the bike is not running hot when I ride it and the coolant level in the radiator remains full. 

12 minutes ago, dictater said:

Also, the bike is not running hot when I ride it and the coolant level in the radiator remains full

There's lies your answer, my guess is the tube from the coolant reservoir to your rad is leaking.

Get a opinion from another mechanic if you can find a mechanic.

Definitely not leaking from the line to the rad, leaking from the overflow tube. 

head gasket for sure . 

you could try some barrs leak ,just for a quick stop .but wont last long .

get your mechanic to pressure test the cooling system, just to prove it .

That's good to get some confirmation but why does it just drain out when it's not running? I filled it with water this morning and it poured out of the overflow as fast as I put it in? 

So just to be clear you are filling to the line the overflow tank #12 and when the engine is not running the water is leaking out of hose # 24  

 

2 hours ago, dictater said:

That's good to get some confirmation but why does it just drain out when it's not running? I filled it with water this morning and it poured out of the overflow as fast as I put it in? 

where are you filling it from ? the tank or rad?

 

2 hours ago, sirmud63 said:

where are you filling it from ? the tank or rad?

 

Ah fixing a mocy by conversation,  always good for a laugh. No disrepect, just its always frustrating and often futile..

43 minutes ago, kaorop said:

 just its always frustrating and often futile..

Add to that one usually never gets to find out what actually the problem was. 

14 hours ago, VocalNeal said:

Add to that one usually never gets to find out what actually the problem was. 

Also not making any sense, good illustration by the way good info.

1 hour ago, Kwasaki said:

Also not making any sense, good illustration by the way good info.

My question was rhetorical but lets see what the outcome is?

2 hours ago, VocalNeal said:

My question was rhetorical but lets see what the outcome is?

Well i think the hose is buggered at No.23 or the coolant bottle is broke.

If OP can run with no overheat it's not a head gasket.

Has he looked at oil another give away of of coolant leaks.

Persacaly. 

On 10/22/2017 at 6:12 PM, VocalNeal said:

So just to be clear you are filling to the line the overflow tank #12 and when the engine is not running the water is leaking out of hose # 24  

 

I kind of let this conversation go as it descended into normal TV nonsense, but yes you are correct. I have since posting replaced the manifold gasket and now find the bike draining more than before. Only when the engine is cool after a ride, meaning usually overnight so I never actually see it happening. I replaced the gasket two weeks ago and the reserved tank is now nearly empty. 

Just now, dictater said:

I kind of let this conversation go as it descended into normal TV nonsense, but yes you are correct. I have since posting replaced the manifold gasket and now find the bike draining more than before. Only when the engine is cool after a ride, meaning usually overnight so I never actually see it happening. I replaced the gasket two weeks ago and the reserved tank is now nearly empty. 

 

So the contents of the overflow tank are all over the floor?  In the morning the o/flow tank is empty but the radiator is still full? 

In theory it can't siphon back into the engine if the radiator cap is good as it would act as a non return valve. 

 

Pinch off hose #25 and blow down hose #24 see if the tank has a crack/leak  in it which has been suggested. 

 

Check the dipstick is there water in the oil. This has also been suggested.

 

My Honda has a pressurized head tank not an o/flow tank so has no spring loaded radiator cap.

 

 

If there are no obvious signs externally of a leak, it must be eating it. Head Gasket possibly. Find a place that can pressure test the cooling system and it will be obvious.