Radiator question

[truckabilly]

I wonder what is this thing in the circle. What purpose does it serve ? I´ve also seen those little cylindres in horizontal orientation. Some radiators have one, some have two and some have none. Can someone give me info on this?

Thanks in advance. 

[Ace-Garageguy]

I know very little about OTR trucks and large Diesel engines, but if that was in a car, I'd say it was a "swirl pot" / expansion tank / fill point.

A swirl pot can often help an engine that may have cooling issues by design. They're also common on race cars that produce significantly more waste heat than their street-driven counterparts.

If hot spots in the engine cause localized boiling of the coolant, small pockets of air will form. Air in the coolant will reduce the heat transference properties of the cooling system. If correctly positioned & designed, the swirl pot will spin the coolant around inside it, encouraging air to bubble out. Bubble free coolant is then introduced into the radiator, where it does a more effective job of transferring heat to the radiator tubes than bubbly coolant would.

I would also guess that an engine with two extra cans or pots or tanks would use one in the "swirl pot" function, and the other would be an expansion tank that the air separated from the coolant would bleed into.

Edited September 9, 2017 by Ace-Garageguy