Should coolant overflow tank be vented or a sealed system?

[svtcards]

So I was asking guys at work if an coolant overflow tank should be vented or sealed completely? I got mixed answers.Now I'm asking u folks.Does a coolant overflow tank need to breath or can or should it be a sealed system?My aftermarket tank has a rubber o-ring under cap which makes it a sealed system.Let me know if o-ring should be removed or leave it the way it is?I was told when coolant temp starts to cool off air needs to go somewhere,which makes sense.

 

[Uncle Gump]

I think the newer systems are sealed... older vented.

Older systems will force coolant... when it exceeds cap pressure... to the overflow tank. It needs to be vented to allow air to escape. When engine cools... a vacuum is created in the cooling system and draws the coolant back into the radiator because the overflow tube is below fluid level in the tank. Again... the overflow must be vented to do this to allow air back into the overflow tank.

 

[19Walt93]

If it's actually a coolant "overflow"/recovery tank, it needs to be vented. If it's a degas bottle like most recent vehicles have, it's sealed. A recovery tank obviously catches any coolant overflow when hot and allows it to be drawn back into the system once it cools because the hose either attaches to the bottom of the tank or is long enough to extend to the bottom of the tank.

 

[svtcards]

This is the tank Im currently using in my truck.It says it's an overflow tank. https://www.ebay.com/itm/232159262086?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=2a37clFFR66&sssrc=2349624&ssuid=P7HsOy4AQvu&var=&widget_ver=artemis&media=COPY

 

[svtcards]

It's a sealed tank none vented that I could see.Oring under cap.What could happen if I continue to use this opposed to a vented tank?

 

[Uncle Gump]

I think it would add pressure to your cooling system.

If the cooling system can't vent excess pressure... exceeding the radiator cap specification... the pressure would continue to build and possibly pop hoses etc...

In order for that system to work properly... the overflow tank has to be vented.

 

[Vindictus]

Removing the o-ring from the cap should let it vent.

 

[55trucker]

So I was asking guys at work if an coolant overflow tank should be vented or sealed completely? I got mixed answers.Now I'm asking u folks.Does a coolant overflow tank need to breath or can or should it be a sealed system?My aftermarket tank has a rubber o-ring under cap which makes it a sealed system.Let me know if o-ring should be removed or leave it the way it is?I was told when coolant temp starts to cool off air needs to go somewhere,which makes sense.

It has to be vented, when the cooling system heats up & expands the coolant is forced past the pressurised rad cap out the hose & into the recovery tank. The air in the tank is displaced by coolant. When the engine is shut down & the fluid in the coolant system contracts the fliud in the tank is sucked past the rad cap back into the main system. If the recovery cap is not vented then the fluid cannot flow into the tank or be drawn back into the main system.

 

[svtcards]

So I wonder if I can just take the o-ring off the overflow tank so it's not completely sealed, would that correct the issue? I also noticed the upper hose expands quite a bit.I wonder if it's doing that because of the sealed tank?Also this past winter coolant did back flow back into tank while it was running.To this day still don't know y?It didn't over heat and I don't have a blown head gasket or anything.

 

[Roert42]

From the manufacturer. "Prevents leaks by helping relive pressure while increasing horsepower."

I would take what they say with a grain of salt.




Although a sealed tank would be able to relieve some of the pressure of the rad, the air would compress a bit and the pressure would equalize.

I feel like it would work a lot better if it wasn't sealed, as originally designed.

 

[Uncle Gump]

I also read on their listing something like... "we won't be of much help but we will try to help you".

I think I would drill a hole in the cap and install a fitting with a drool tube.

 

[alwaysFlOoReD]

Is there a radiator with a cap?
Is the overflow line from the radiator going to this tank?
If the radiator does not have a cap then the tank cap is doing what a radiator cap normally does. And it needs to keep pressure in...to the pressure that is specified. Usually between 13 and 16psi.
Do you have some pics of your system? Post them up.

 

[55trucker]

Curious........what happened to the original tank?
It would be a combination tank, one side is the coolant recovery tank, the other side is the windshield washer reservoir..... the oem piece has snap on caps.

 

[svtcards]

Curious........what happened to the original tank?
It would be a combination tank, one side is the coolant recovery tank, the other side is the windshield washer reservoir..... the oem piece has snap on caps.

Didn't have room for it.So I bought 1 that was a better fit

 

[svtcards]

It's definitely sealing coolant from back filling back into tank.will need to put a vent into or just unscrew the cap a tad so I will vent when needed