Pressurized coolant reservoir

Joined
Oct 17, 2019
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225
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Close to arctic circle
I think too that 21 psi is quite high pressure that puts stress on a lot of parts in the cooling system. And yes when plastic becomes brittle, added pressure might blow a hole in the tank. I don`t know why modern cars have so high coolant pressure. I believe my volvo have up to 14 psi pressure
cap on the expansion tank. When i went to mechanic school we were taught that 14 psi is max pressure when pressure testing the cooling system, above that could cause damage.
 
Joined
Aug 5, 2002
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21,429
Location
Silicon Valley
The reason they have the reservoir tank pressurized instead of the old radiator cap pressurized but the overflow tank not pressurize, is that the cap should be at a high place so it will burp correctly, instead of having bubbles inside the system and ruin things.

If you pay attention you will see most of these pressurized tanks instead of unpressurized reservoirs, the radiator sits at a lower position than the reservoirs. This is the trend for aero or cosmetics so something has to give: the plastic tank is now pressurized.
 
Joined
Jul 18, 2008
Messages
101
Location
Gaul
Many/most/maybe all modern long-life coolants last a lot longer when you don't constantly expose them to the atmosphere.
 
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