Proper bleeding procedure
 

Hello everybody. I've been away from this site for quite some time now. Actually I read the posts but haven't posted anything. Anyway, my vehicle is a 2003 BMW X5 3.0 (E53, M54). It now has 182,000 miles. I am a GM technician for over 20 years and do 95% of my own work on the Bimmer. Just yesterday I replaced the waterpump with a metal impeller one, thermostat, ac and waterpump belts, upper and lower hoses with new coolant sensor and oring in lower hose. Drained radiator via drain plug at bottom right of radiator. Rest of coolant came out via removal of waterpump and lower hose. Didn't seem much coolant came out. ??????? Anyway, bled cooling system by pouring (BMW) coolant in expansion tank with bleeder screw removed. Poured until I got a steady stream out of bleeder screw. Closed bleeder screw. Ran vehicle with cap off to make sure no air pockets and opened bleeder screw one more time to make sure I still have a steady stream. Yes. Let vehicle run for 15-20 minutes. Temp gauge in the middle at 12 and plenty of heat. But upper radiator hose is hot and bottom hose is cold. ???????. Let vehicle sit for 2 hours with a fan on engine to cool down rapidly. Checked coolant level again. Topped off with water and coolant. Let vehicle run again. Temp gauge in middle and plenty of heat. Drove 40 miles from work to home. Excellent heat and no overheating. Temp gauge stays in middle. But lower radiator hose is cold to the bone. What gives????? Is there something I'm overlooking??????. Is this normal on this engine???? Please help...... Any advice would be greatly appreciated. BTW, changing the waterpump resolved an issue with a mysterious rumble on slight throttle application that I've been having for the past 2 years. Yeah!!!!! One INDY SHOP and BMW fanatic told me it was a motor mount and possibly the Vanos Unit. Lol.... Anyway back to the lower hose being cold. Please help.

Really. Nobody has an answer?

Sounds like you have an extremely efficient radiator.

You didn't mention if the heater is blowing hot air? Typically the place the ends up getting the air bubble is the heater. Your filling procedure sounds fine, although I like to turn the key on and the heater turned all the way to 90 with the fan at the lowest speed while filling to make sure the heater doesn't have any air.

It takes two people (easiest) to determine if all the air is out of the system. After doing everything you did when filling it, start the engine with the radiator cap removed. Have 2nd person rev the engine, and you should see a stream of coolant shooting into the expansion tank from the side near the top of the tank. Kinda looks like someone is peeing into your expansion tank. That is verification your waterpump is working and you have most of the air out of the block. If you don't see that, then open the bleeder screw to let air out, when coolant starts overflowing, close the screw again, now you should see the stream.
Small chance that your thermostat isn't opening, and the cold hose would be a result. But, your thermostat is monitored/controlled by the DME and you would get a check engine light for that once your engine was up to operating temp. The fact that you drove 40 miles without overheating indicates your engine is getting cooled.
You could check to make sure your lower hose is full by waiting until the thermostat has cooled off and closed then disconnecting the lower hose at the thermostat.
You're right in thinking the lower hose should at least feel some warmth to it, but it shouldn't get hot.

Yes. I have plenty of heat. By the way, the next day my expansion tank sprung a leak. So, the X is down. Parts will be in tomorrow and installed Wednesday.