Radiator vent line dimension?

[Daniel Lorenz]

Going to route the vent line soon from radiator all the way back to the header tank.
I read that 3/16 hose is appropriate, while others say 3/16 pipe.
The difference is quite big, since the pipes inner diameter is only 1/8.
Will the smaller ID pipe be sufficient for the needs?
Cause it would surely be easier to route all the way back.

 

[Ian Anderson]

Going to route the vent line soon from radiator all the way back to the header tank.
I read that 3/16 hose is appropriate, while others say 3/16 pipe.
The difference is quite big, since the pipes inner diameter is only 1/8.
Will the smaller ID pipe be sufficient for the needs?
Cause it would surely be easier to route all the way back.

The pipe with the small internal will suffice as you do not want to move masses of water….only vent any air back to the header tank.

I used to run with no bleed / vent line and after a year and around 3000 miles I probably got an egg cup full of air that I bled out of a manual crack outlet

In reality once bled you should not get air into the radiator

Ian

 

[Devin]

In a similar question…can the radiator vent line be merged with the return heater core line to save from running a separate line in the spine for both?

 

[Daniel Lorenz]

The pipe with the small internal will suffice as you do not want to move masses of water….only vent any air back to the header tank.

I used to run with no bleed / vent line and after a year and around 3000 miles I probably got an egg cup full of air that I bled out of a manual crack outlet

In reality once bled you should not get air into the radiator

Ian

Thanks for the input, then brake line will suffice.

About the statement that no new air gets into the system, well.. high HP engines tend to push some air past sealings, but in theory it shouldn't be like that. But we all know how well theory is to reality.

 

[Daniel Lorenz]

In a similar question…can the radiator vent line be merged with the return heater core line to save from running a separate line in the spine for both?

I would say no? Since you need to return to air and not water (top of header tank where there is no water.

 

[Paul Hendrickx]

as per model ......
small line to expansion tank just to transport air.... en as said ...... combustion gasses will go in to the circuit, in very very small amount ..
every car has them .... even on the cooling system of ev battery...

 

[JP Verweij]

I run 3/16 copper pipe from top rad through the tunnel to the header tank with 3/16 hose as coupler on both sides.
I also run a 3/16 vent line from top manifold hose to header tank as my headertank sits lower.
To accommodate, I have a catch tank to for overflow from and return to header tank also.
Header tank has a pressure cap, catch tank has not.