Radiator Loosing Fluid

[naveed]

I changed my radiator and removed the thermostat. When I refilled it with water wetter, it filled up pretty quickly with probably about half a liter in the radiator. I filled the about 0.3 liter in the compensating tank. After a few track days and races, I saw that my compensating tank is empty; I checked radiator and I cannot see the fluid as well. I filled up the radiator again and it took probably about a quarter liter to fill up.

My conjecture is that there was air trapped, which caused the cooling system to not full up properly and after I rode the bike, it sucked all the coolant and as there was not enough coolant, the radiator and compensating tank was empty. I cannot see any signs of leak from anywhere, so I don't think it leaked.

I would be very grateful if you have any suggestions or comments about this situation.

 

[ReidMcT]

That is possible. It also is possible that your water pump seals are leaking, which is not uncommon on the 390. Check your oil to see if it is a bit high or seems muddy. I will be replacing my seals soon with better seals from a 450. There's a thread about it with the details someplace on this forum.

 

[ReidMcT]

Here: https://www.rc390-forum.com/forum/e...7-water-pump-linkage-failure-6.html#post24292

Use 2 seals from a 450. (Read subsequent posts for clarity)

 

[naveed]

Thanks for the help! The oil level is the same as I filled it up and it doesn't look muddy. I will look at it more carefully and see if I need to replace the seals.

 

[ReidMcT]

You may not have any problem now. You definitely under filled the system the first time. So the radiator may not actually have lost any coolant.