overflow coolant can question

[RayBan GST]

I have a hole in my coolant overflow can and it was beyond fixing , so i changed it with a home made one ( a 1 litre can with exact size of the stock overflow can)

but no matter how hard i tried to fix the cap on the can i could not let it seal its like impossible , every time i seal it after second it will pop up again

the question is will it hurt if i run with an open overflow can ? i mean it has the pipe and everything but the cap is not sealing properly

thanks to let me know

cheers

 

[RayBan GST]

maybe iam wrong but do i not need this pressure to push the coolant back to my system ?????

 

[JonathanNL]

maybe iam wrong but do i not need this pressure to push the coolant back to my system ?????

No, you need a vacuum inside the system. Which will suck the coolant back thrue the pipe as long as it is submerged in coolant in the overflow can.

 

[Defiant]

The expansion tank must be vented. The pickup tube must be at the bottom of the tank so it pulls back coolant instead of air. The expansion and contraction of the coolant as it heats and cools is both how it works and why you need it. Trying to seal it will only fail. If it wasn't for the sloshing, a bucket would work just fine.