Hi all. Quick question about 03 pro rad cap it has a brass insert in it.I think it's thermostat but would like to know for sure. Also has anyone a picture? Mine is hollow and spews coolant out of it..should it be hollow or not?

Thanks

Quite a few years since I have looked at one but I think what you are calling a brass insert is like a large thin washer that holds (or should hold) a rubber seal in place. The rubber seal used to soften and thin with age, as this seal gets thinner and thinner the pressure at which coolant boils out gets lower and lower.

You can make a temporary fix by cutting a rubber washer from an inner tube

It's not a thermostat but a pressure relief valve. The pressure is written on the cap but is usually about 14psi. So if yours is hollow and flows freely in both directions then it needs replacing. The system is pressurized to raise the boiling point of the coolant. The cap is also designed to allow air to be taken in if needed as the system cools.

Normally there should be no coolant spitting out but you might get a bit on the first ride after filling the radiator. If any coolant comes out after that it's usually a fan problem (most commonly the thermo-switch).

Just get a new cap anyway - they don't last forever.

Chris

Brisbane Australia.

Thanks for fast replies really appreciated.

I should have mentioned it's a plastic screw on cap not the conventional type used on most bikes.inside there is what appears to be brass piece.that takes up most of inside of the cap.

Yeah Kev, same description applies to the plastic cap - it should have a pressure relief valve and not vent until about 14 psi has built up in the radiator. It should not flow freely in both directions.

My gasser has the plastic cap also. Sorry I don't have a picture of it.

Chris.

Forgot to mention - the part number is BT280232032. You didn't say where you are from but they cost about 20 pounds in the UK.

Thanks aussiechris. I'm from ireland. Il get into my local dealer today and get sorted hopefully by weekend.