Question....(Might sound A bit Stooopid)

[Midlander]

Right then,,, following on from previous thread on water pump......

Having had all the gubbins out to replace the pump....part of the job entails disconnecting the expansion tank pipe from the top of the Rad.

My question is....being as there's only one pipe from the rad to the expansion tank which has a Filler cap and a little vent thingy on the top.....Wher does the water go when the level drops?

I can see no way how the water can get back into the radiator as the outlet hole to the pipe from the neck of the rad is above the rubber flange thing on the radiator cap.

is it magic LOL?

 

[Lazy-Ferret]

Right then,,, following on from previous thread on water pump......

Having had all the gubbins out to replace the pump....part of the job entails disconnecting the expansion tank pipe from the top of the Rad.

My question is....being as there's only one pipe from the rad to the expansion tank which has a Filler cap and a little vent thingy on the top.....Wher does the water go when the level drops?

I can see no way how the water can get back into the radiator as the outlet hole to the pipe from the neck of the rad is above the rubber flange thing on the radiator cap.

is it magic LOL?

It works on suction...

The idea is, the pipe runs from the top of the radiator, into the bottom of the expansion tank... To work, the expansion tank has to have enough water in it, to cover the pipe. The idea is, when the water gets hot in the engine, it expands, pushing past the radiator cap along the hose and into the expansion tank, as it cools, it creates a vacuum and when this pulls the water back again.

This is why it is important to get the radiator full to the very top, so any air in the pipe is pushed through to the expansion tank, bleeding the system.

 

[Midlander]

Ahh I see now...cheers for that...

 

[Banshee]

It works on suction...

The idea is, the pipe runs from the top of the radiator, into the bottom of the expansion tank... To work, the expansion tank has to have enough water in it, to cover the pipe. The idea is, when the water gets hot in the engine, it expands, pushing past the radiator cap along the hose and into the expansion tank, as it cools, it creates a vacuum and when this pulls the water back again.

This is why it is important to get the radiator full to the very top, so any air in the pipe is pushed through to the expansion tank, bleeding the system.

I made this mistake and it nearly proved very very costly