[VanAlarcon]

I have a new radiator, fan, etc and my fan will not turn on. The first time I started the car with the new parts it was on. I have it mapped to MHD stage 1. Before starting it I selected max cooling hoping it would tell me more about it, all it did was turn it on. So I started the car the fan was on it was loud so I put 2 and 2 together and I shut off max cooling.
There were no overheating issues that day I drove about 12 miles.
The next day I noticed my coolant temps climbing when at idle, it hit 243F bmw pop-up says it’s overheating drive cautiously. It went down around 200-207 while cruising.

It has yet to spike that high again but I notice the fan still won’t turn on even when hitting temps of 220F.

I had read codes and the only one up was
2EFE - DME: Electric fan, activation
This code was gone the next drive but still the coolant temps could not stay stable when idleing.

[BRG_N54]

First of all it might help if we knew a bit more about why you replaced these things and exactly what was replaced, besides "etc". I did my cars as preventative, but if there was some kind of front end collision you were repairing it might lead to different hypothesis of the issue.

Second, we would assume you did the correct coolant bleed process as outlined in the Bentley manual, including leaving the coolant cap closed.



The water pump should give an error code if it is failing, but the thermostat may not show anything other than an overheat. Also, we must assume you used BMW coolant mixed 50:50 with distilled water. Whatever "tuning" you are making to the system will not help us to aid in your diagnosis either, as I can rule that out of my scenario. The more one deviates from known conditions, the more likely strange behaviors will present themselves, and the more difficult to troubleshoot, in such a complex system as the N54.

[VanAlarcon]

Originally Posted by BRG_N54

First of all it might help if we knew a bit more about why you replaced these things and exactly what was replaced, besides "etc". I did my cars as preventative, but if there was some kind of front end collision you were repairing it might lead to different hypothesis of the issue.

Second, we would assume you did the correct coolant bleed process as outlined in the Bentley manual, including leaving the coolant cap closed.

[img]https://i.ibb.co/ZBmfykM/E90-Bentley-Coolant-Bleed.jpg[/img]

The water pump should give an error code if it is failing, but the thermostat may not show anything other than an overheat. Also, we must assume you used BMW coolant mixed 50:50 with distilled water. Whatever "tuning" you are making to the system will not help us to aid in your diagnosis either, as I can rule that out of my scenario. The more one deviates from known conditions, the more likely strange behaviors will present themselves, and the more difficult to troubleshoot, in such a complex system as the N54.

Thank you it turned out to be the fan motor blew. Replaced that and everything works as should.