I was talking to my supervisor at work and I told him I wanted to change my coolant. He said I would have to bleed the system?? Do i need to bleed it or just drain it all out? It's a vr commodore v6
Bleeding the system is what you do after you have dumped out the old coolant, flushed the system and then refilled the system. So After you have filled the car with new coolant, Started the car, keep filling the car up till it takes no more. Replace the radiator cap, get the car up to temp, then undo the top screw on top the thermostat housing, this is where the top radiator hose is connected. once a nice stream of coolant is flowing out of the screw hole, the system has been bled, be sure to have the heater on full heat also as air get trapped in there also.
It also helps to have the car facing uphill when refilling the radiator.. Ive always done this, and Ive never had one problem with trapped air etc.
Just to add a bit more, make sure the system is well flushed as mixing two different types of coolant can cause solids to from which can block the radiator. Remove a heater hose and flush in both directions from there. When refilling, have the bleed screw open to allow air to escape.
Bleed the system with the bleeder screws and with the correct radiator fitting or cut the bottom of a large neck plastic bottle (such as a gatoraide bottle) wrap a bit of electrical tape around the threads and invert it into the radiator neck, fill it and watch the bubbles of trapped air pop out.
