Coolant Tank Cap Function
 

Hi guys,

My understanding is that for a typical front-engined car with the radiator in front and such, the pressure cap would maintain pressure up until a set point and let the coolant overflow into the overflow tank, and draw it back in once the system cools down. There have been a few threads about cooling issues, and from reading many threads, I came to understand that the bleeder valve on our car regulates the pressure and lets the coolant overflow into the expansion tank. So what exactly does the tank cap do, besides being a cap?

other than being a cap, hmmmmm lets see..... adds a splash of blue color to the interior of the rear trunk. it is not a pressure relief and recovery cap like the typical radiator cap in a overflow recovery system.

It does hold pressure and if it doesn't you'll have coolant boiling out.

keeps your head from cracking. All for the bargain price of $20.

Or you could lose an engine for $20. A matter of perspective.

Search this forum for air pockets.

Funny that Porsche is on their fourth iteration of this cap that is only a cap. :confused: