where does radiator fluid disappear to?

[sydbusaboy1300]

my '99 Busa seems 2 drink a lot of radiator fluid. it doesn't leak out anywhere (not that i can see any green stuff on the road / garage floor).
my mechanics have no idea what is wrong (unless they pull the engine out & strip it - could be $$$). its been pressure tested & everythin seemed fine... it does however overheat in peak hr traffic - really bad in Sydney these days...
any ideas whats wrong w/ my bike ?

[micbusathens]

gasket???

[BusaWizard]

Cooling fan coming on like it should?

[proud dad]

pull the plugs to see if any coolant getting on them.if it is,it's a head gasket.


oil is not changing color is it?

[Aquaman]

Sounds like it could be a blown head gasket. Could be going out your pipe. Is the bike running like crap?

[rc51ny]

Well, it's going somewhere. If it's not on the floor/road, then it doesn't sound good to me!

[sydbusaboy1300]

*apparently its not the h/gasket as the pressure test didn't reveal anythin unusual

*cooling fan doesn't even come on - makes me wonder if its not the thermostat (maybe w/o the fan workin the fluid just evaporates)

*its not all over the plugs as its just had its (late - 55k) major service and everythin was fine, includin the oil

*and it runs fine - like new...strange

[TallTom]

I am going to suggest that your overflow/purge circuit is faulty. As the temp goes up and down the overflow tank is used to take coolant in and out. I am going to suggest that perhaps what is happening is the engine warms up (worse when it overheats), and tries to take on fluid from the overflow and there is a leak in that circuit. You won't see it leak when cold and if its leaking at speed it probably just boils/burns or drips off. Do you ever smell coolant at all? You already know that the overflow tank is low since you know you take on coolant.

Then when it cools off it purges back into the overflow and as the process repeats itself it will leak out coolant thru that circuit.

Hey I'm just trying to use some logic here. It is the only external thing I can think of. If it is passing pressure test it has to be something external from all I can think of.

Let us know what you learn.