Originally Posted By: edwardh1
I rented a pontiac g6 in california, the coolant recovery bottle is part of the cooling system and is pressurized so that if it ever looks low when hot you can not add coolant (to the recovery bottle) when its hot.
Are all new cars like that?
my 2004 toyota has a vented coolant recovery tank that you can add coolant to at any time.
is this a GM thing? pressure cap on the coolant bottle? the pontiac lost 1/2 inch of coolant each 500 miles (comparing cold levels)
Just note that its low on coolant and then add some after it's cooled off. So long as there's coolant IN the surge tank, you're guaranteed that the block is completely full. Being low doesn't hurt anything unless the surge tank becomes empty, then air is going to be drawn into the engine itself.
FWIW, there's not set pattern of which vehicles use pressurized surge tanks and which ones use conventional overflow tanks, even among individual manufacturers. Old (80s) Jeep Cherokees used surge tanks, then later switched to conventional overflow tanks. Chrysler LH cars (1993 and later) use surge tanks, but PT Cruisers use conventional overflow tanks. Both systems work. The big drawback to the surge tank type is that the tank has to be pressure tolerant. Its big advantages are that you always get an indication of coolant level, and fresh coolant is always circulated through the surge tank. With a conventional overflow tank, you can have a situation where an air leak in the hose from the radiator pressure cap to the overflow tank will prevent the radiator from ever drawing coolant back out of the overflow tank, so if this happens you can be VERY low on coolant but the overflow tank level will still be normal. Its always a good idea to periodically check the actual radiator level in systems with an overflow tank, or squeeze a radiator hose with the engine cool and confirm that the level in the overflow tank changes when you squeeze.
