E46Fanatics - View Single Post - [Cooling System Upgrade] 1-BAR Radiator Cap
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Old 10-03-2012, 10:39 PM   #10
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Join Date: Sep 2011
Location: Toronto, Canada
Posts: 610
My Ride: '02 330Ci M-sport
Originally Posted by Solidjake View Post
So basically when the system is fully hot up to temp, when we loosen our caps that is why a lot of steam/hot air comes out. Wouldn't using this cap to lower the pressure force the water pump to work harder to move coolant around as it's not pressurized as it should be?
The water pump can only work at one speed since it is belt driven, unlike modern electrical pumps. It cannot compensate for the reduced cooling efficiency due to the reduced pressure.

Last edited by ImolaSix; 10-03-2012 at 10:43 PM.
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