My water pump doesn’t seem to be coming on with the engine running

[AlexHall886]

My car is a 2011 n55 dct m sport. I bought it, unbeknownst to me, with a dead water pump. I replaced the water pump and thermostat with a pierburg water pump and whichever thermostat fcp euro sells. It has been doing decent. Before, I couldn’t drive it 5 feet without it overheating, after it started doing it. I brought it home after buying it, I was able to drive it back and forth a few miles to work for two days. It started overheating one day on the way home from work and I had to limp it.

I got the new water pump and thermostat installed and I thought I was in the clear. To be fair, I do drive the car hard. I do a pull almost every time I drive it. I’ve had one instance where the red coolant light came on since replacing the water pump and thermostat. I drove it spiritedly to a store, it got to probably 200° oil temp, spent 10 minutes in the store, came out to drive home and a mile from the store the red coolant light popped on. I immediately pulled over and shut it off and drove it home without issue. Today, I took another spirited drive, got it up to full oil temperature, sat with it idling for 10 minutes while I waited for someone, drove to an atm, sat with it idling and the yellow coolant light came on and the fans came on full blast. Again, turned it off and on again and drove home without issue.

I find it hard to believe, and I would be incredibly disappointed if the water pump and thermostat have failed already. I have done the bleed procedure three times, with the cap on, since I got home today. The pump, or whatever makes the clicking noise when you start the bleed procedure, is clicking. I don’t know what it is. The pump ramps up and down several times, stops for a while, and then stays steady for a while. In short, it seems like the bleed procedure is working. Before, when the pump was dead, the bleed procedure would not start. The thing that is really concerning me is that there is no flow in the expansion tank with the engine running. I remember reading somewhere before that it only kicks on at certain times, but I’m pretty sure I remember checking it right after the install and it was flowing. When should I be looking for it to come on when the engine is running?

One last thing I can think of, I did not fully do the bleed procedure after installing the pump and thermostat, but I vacuum filled it, so I didn’t think it would be necessary. Any input would be greatly appreciated.

[tracer bullet]

I'd start w/ the bleed procedure, it's super easy. It'll help ensure you don't have air pockets, and it'll also let you know if the pump is indeed working.

[AlexHall886]

Originally Posted by tracer bullet

I'd start w/ the bleed procedure, it's super easy. It'll help ensure you don't have air pockets, and it'll also let you know if the pump is indeed working.

I did it three times and took it for a test drive. Ambient temp here in Virginia is about 80°F. I monitored the coolant temp with a Bluetooth code reader and it stayed between 220-230°F. From what I’ve read, it looks like n54/55 run really hot. I think the bleeding did it.

[tracer bullet]

Nice! Hope so.

[1and1]

Coolant system was the bane of my existence for a while, and the thing that let me finally fix it, the thing I wished I had done to begin with...

Get a radiator pressure test kit (that's the super important part) (https://www.amazon.com/dp/B08HWK7KHV)
20-21psi is the max pressure to use for testing...
Pull the fan shroud out
pressurize the system
find the problem(s)
profit