When a coolant pump begins to fail, youll notice that the car tends to overheat at low engine speed, such as sitting at a stoplight. When you accelerate, the engine temperature will drop. Now, this is not always indicative of a coolant pump failure, but a good starting point. You may also want to try squeezing the top radiator hose with the engine warmed up and running. You should feel pressure build up on the back of the hose and surge once it is released. If you feel no pressure, its a fair bet that the coolant pump is failing. BMW updated E90 models with an electronic water pump. This means you may replace your coolant pump due to electrical failure. The most common problem with these pumps is a fault code for coolant pump volume. If you remove the water pump from your E90 and plan on reinstalling it, store it with coolant inside, otherwise it will corrode and fail shortly after reinstalling it. Always replace aluminum fasteners each time they are removed and never reinstall a questionable coolant hose.
This can be a tough part to change as it is tucked away and behind many components. I like to remove the radiator when I have to replace a water pump, it adds time to the job, but makes it a lot easier. If you have an all wheel drive E90 or one with active steering, youre going to have to remove the radiator anyway. So I say just go for it and make your life easier no matter which model you own.
In this article, Ill go over the steps involved with replacing the water pump on BMW E90 models. Be sure to work with a cool engine and confirm the cooling system lacks pressure before opening cooling system.
Remove engine splash shield. See our tech article on splash shield removing.
Drain cooling system. See our tech article on cooling system draining and filling.
Remove thermostat. See our tech article on thermostat replacing.
Working at the back of your water pump on right side of engine, loosen both hose clamps (green arrows)
Once all the fasteners have been removed, remove the water pump from engine.
Install new water pump and evenly tighten fasteners. Install coolant hoses and tighten clamps. Connect water pump electrical connector. Pay close attention to electrical connector. Once you think it is installed, try to pull it off. I found that the seal inside the connector can swell from oil contamination; this inhibits the connectors ability to fully seat and lock into place. If it will not lock into place, replace the seal on the electrical connector. It can be replaced separately from connector.
Install thermostat, radiator and cooling fan. Install splash shields and fill and bleed cooling system. Remember to check cooling system for leaks and top up coolant when complete.
Comments: Nick, thanks for your response to the previous question I posted. It's been about two weeks since I replaced the water pump and thermostat and everything was going well until today. Exiting my car I heard my cooling fan absolutely wailing like the car was overheated and noticed some coolant drops in the engine bay. I'm troubled because after I let the car cool down to check the coolant level which was still at max I attempted to circulate the pump to get the air out of the system and I am not hearing the new pump circulate any coolant through the system i.e. placing my ear on the expansion tank to hear the air bubbles exiting the system. I should say that after the initial replacement I was still getting a P1028 code which indicated that the coolant temp was too low! I ruled out a bad thermostat because it was brand new.
I am stumped because this is a brand new pump and thermostat!! There should be no way that the pump has failed me already! I don't know what to do or how to diagnose the problem now. I can assure you that all electrical connectors were cleaned before the install of the new components and that the pump initially circulated the coolant like a champ. There were no leaks in the system because I left the engine cover off to check for any leaks form the hose connections for about a week after install! Now I have no flow at least from the expansion tank and my thermostat amber light has come back on! I'm in need of some help because I certainly do not want to have to buy a new pump and thermostat.
I have now plugged in my battery charger to leave my car charging overnight to see if maybe my battery was too low on juice to run the pump properly and try again in the morning. But if that doesn't work I certainly don't know what to do next! I don't want to be stranded again with my 4 month old son and wife... and don't want to blow a head gasket either....or have to buy new parts! Do you have any suggestions for how I should proceed?
July 14, 2014
Followup from the Pelican Staff: I would confirm the coolant level is correct. Then try bleeding the cooling system again. If there is no air trapped, turn on ignition and listen for the water pump. You may have to have a friend turn ignition on while you listen. If the pump is faulty, you may hear a ratchet type sound as it tries to turn, then it will stop. - Nick at Pelican Parts
Comments: What's the part number for the electrical connector seal? I'd like to have it on hand so the process can be done in one go.
June 30, 2014
Followup from the Pelican Staff: Give our parts specialists a call at 1-888-280-7799 and they can help figure out which part or repair kit you need.
- Nick at Pelican Parts
Comments: Is there any significant difference when doing an xdrive e90?
June 21, 2014
Followup from the Pelican Staff: The X-drive system makes it tight. So you will have less room to work. But that is all. - Nick at Pelican Parts
Comments: I popped one of the retaining clips when removing the one of the cooling hoses linked to the Thermostat. It's the smaller of the two retaining clip thermostat hoses... I'm waiting for my parts to arrive but was wondering what the best way and orientation to reattach the retaining clip? I see that the ends of each clip are pointed in different directions and didn't know if I had to slide the retaining clip over the hose or insert the ends first than slide over the hose? I obviously don't want any cooling system leaks! Thanks for your fantastic tutorials and hopefully the reinstallation of the thermo+pump is successful... At least it was for my valve cover gasket!
June 9, 2014
Followup from the Pelican Staff: When I pop one off, I place one side on, then pop the other over the hose end. - Nick at Pelican Parts
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