How do I bleed my radiator on my BMW z4 2004 - 1998 BMW Z3 Roadster

Is your radiator cap good?
Was the air bleed from engine after thermostat was changed?
HOW TO BLEED COOLING SYSTEM ON BMW - YouTube

You may have air in the cooling system, you need too bleed it using the bleed point on the top right of the radiator as you stand in front of the car

I can think of a few other things to check. Are you sure the radiator is not clogged and just needs cleaning out? Are the fins on the radiator bent close preventing air from flowing through the radiator? Is there a bleed screw somewhere on the engine cooling system that you are overlooking. If so, bleeding it the old fashioned way as you did will not work. You must use the bleed screw. In addition, are you positive you do not have a blown head gasket? Symptoms are overheating, loss of coolant with no apparent leak, white smoke from the exhaust, a white foamy substance on the underside of the oil fill cap, oil level overfull, and air bubbles escaping from the radiator with engine running, radiator cap off. I hope you do not have a blown gasket and wish you the best of luck finding the culprit. Merry Christmas.

check a couple of things check the fuse for your heater make sure its working and why cant you bleed the radiator?

you can't bleed just the radiator, you have to bleed the cooling system through the bleed holes while it's hot and pressurized and running.

two areas: bleed valve on thermostat housing, or overfill cup next to radiator.

Sounds like the thermostat has stayed closed you will need to change it as it will blow the head gasket, very common on this model.

Also when you bled it though you may have left some air in the system this would also stop the heating working, they can be a pain to bleed through keep sqeezing the water hoses as you are bleeding it through and do not bleed it from the lower part of the radiator as it will be hard to get the air out as air will stay at the top, you should bleed from the top.

the thermostat (on bmw replacement parts) have an arrow that has to be installed facing upward.if this was done correctly,to bleed the system usually there is a bleeder screw on or near the expansion tank(where you fill the coolant) and possibly on the thermostat housing. i would recommend opening both bleeders and keep filling the system with coolant closing the lower bleeder first and then allow the rest of the air purge from the other bleeder screw.make sure the coolant stays full and be patient you can't wait TOO long.

look on the radiator next to the top hose connection, also on the thermostat housing there should be a small screw, bleed the thermostat housing first then the radiator

Seeing as you just replaced the water pump, there should be little fluid remaining.

Remove the drain plug from the bottom driver's side of the radiator. Let it drain into a large pan. Once draining is complete, remove the bottom radiator hose from the passenger side of the radiator just to get everything out of the engine if the engine block drain plug didn't remove all of the fluid. Replace the plugs and lines if removed.

Fill the radiator reservoir and start the engine with heat controls on high. open the bleed screw beside the filler cap just enough to let air out. Keep refilling reservoir as the engine sucks it into the radiator. Only fill it to the cold line. Once it stops moving below the Cold/KALT line, replace the cap and close bleed screw.

probably an airlock in the heater matrix---bleed radiator while engine running with the bleed screw located near the filler cap,when no air escapes should be ok but will need a water top up----good luck.