I've never tried that and I'm not sure it will work. As I understand the system, the return line will only get flow when the valve in the rear releases an overpressure situation (like when you remove a heavy load after the rear has pumped itself up). I think you'll still need to bleed from the rear valve bleed nipple. This must be done with the engine running and be sure you have the car on ramps as the rear can drop a few inches when you release the pressure. You should also replace the filter if you haven't already. It's in the top of the tank and filters the return fluid. If you do try to bleed it your way and it works, be sure to replace the filter AFTER you are done. Let us know how it goes.

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold