Merc 200hp water pump outlet pipe

[nacimientobound]

On the 2.5 water pump outlet, the water feeds into a small 1/2" diameter x 3" tube that then connects to the tube that feeds up to the motor. As those two tubes are different diameter, what makes the connection tight to ensure full water flow to the motor? Is there an o-ring that fits over the smaller pipe and then the larger pipe fits over that?

Thanks

[flabum1017]

The short tube is just a guide (guides the water tube into the pump housing), the tube that feeds the motor goes into the grommet in the water pump when the LU is bolted up

[nacimientobound]

thank you.