Interesting that these figures are so high. I'm using diagnostic tool and both my vehicles are running between 80 and 90C. Yes running hot burns the fuel much better and more complete. This is another reason why premium fuel is recommended for these types of engines, it is more stable under heat and pressure.

My N62 coolant is at 101-103c in most driving conditions, and regardless of outside temp. I can get it to 118-119c when operating at 5,000rpm for several minutes while towing in the mountains and have seen 121c on a few occasions.

My oil comes out almost as clean looking as it goes in. No condensation build up worries here.

Lower cyl wall and head temps would allow your N62 to run more aggressive timing under "spirited" conditions. The effect on the volatility of the fuel, especially on an already hot day, is equivalent to about 2 pts more octane. I'm talking getting into the 90C ranch vs. 110C+. If you go too cool then you can have fuel fall out of suspension, etc. That's not a BMW thing, that's a gasoline fuel thing.

Now whether the computer actually would or not, I dunno. Theory of operation on the DME 7.2 (I know, your's is different - work with me here) says it monitors and continuously varies ignition timing. I'd really like to know if a cooler stabilized running temperature would correlate with a change, and in what parameters. These engines are well into stabilized closed loop operation well before 200F.

So, this clearly calls for some "Ok, let's see if we can get some insight into this." Well, I hear it calling. So here's what I think I'll do.

I have data logging stuff that will continuously record and generate data files on parameters I select. So just off hand, fuel usage, ignition timing, knock sensor activations, O2 sensors, calculated load, commanded throttle position, actual throttle position (nanny-ass torque-management keep yer ass right-side-up computer anyway), engine rpm, engine temp, ambient temp, air mass being ingested, vehicle speed, and so forth. Hmmmm. Cool. I'll try to generate maybe an hour or 2 hours or however much of worth of running over a certain loop, then I will do the same after modifying the X5 to run stabilized around 195~200. I am going to do that mod anyway, so what the hell, I may as well record a bunch of stuff and play.

I am not so naive to think that there is any sense of "controlled conditions" in this plan. I'll do it anyway, and I should be able to post the gathered data. BUT, I'm not going to state any conclusions. Most of us know what "If you torture your data long enough, it will confess" means, and I think I'll avoid that possibly contentious issue; I'm doing this for myself anyway, not trying to get someone else to make that leap. But I'll endeavor to post the info, because if someone else did something similar, I'd certainly be real interested to see what went on.

But, don't hold yer breath; this will not occur until at least after April 21 (busy with work until then, and then on April 21 is the Seattle Supercross, and tickets are in hand, so I sure won't be messin' around with any cars on that day, so......shrug, prolly in May then.

Civdiv99, i like yoru data mining project... are you going to use some artificial intelligence and nural networks to discover hidden relations among parameters? ;) you'll ultimately reverse engineer the DME!

As for the OP, the operating temperature depends on the T-stat you're using. since i live in a rather warm country, with temperatures reaching 35C in summer, i've put a Tstat that regulates my operating coolant temperature at 85C (185F)...

I need to follow-up on my last post regarding the testing of the aux fan. There are many posts on aux fans, but not many on X5 aux fans! Safe to assume they are not all the same!


Do not jumper fan control signal as mentioned in my previous post. This is not a valid/proper test for the X5 aux fan and it will not verify proper operation. The aux fan requires the presence of a proper pulse width modulated (PWM) signal in the 5 volt peer-to-peek range. The application of 12 volts on the control signal could damage your fan. Do not do this.



The best test for your fan is to let the X5 reach normal operating temperature, turn on the AC to full blast lowest temperature. The fan should come on period.


If the fan does not come on with this test, unplug the fan connector and carefully measure the DC voltages at the connector. If you have +12 Battery Voltage on the large wire and about 3.8 DC volts on the small control wire. Then the control circuit is good and your fan is not responding*** Be very careful measuring the control signal not to short it out. The control signal is coming from the control computer!


Optional: While making the control signal measurement, have a helper turn on and off the AC, the voltage on the control signal should change as it switches on and off. If you were to look at the control signal with an oscilloscope you would see the duty cycle change between 5% to 50%. The most important point is that the average DC voltage is changing. Do not make any assumptions regarding the level of the voltage with it on and with it off. If control voltage changes, the duty cycle is changing so it safe to assume the signal is good.


*** I took the old broken fan apart to satisfy my curiosity. I found a very complex control circuit board with many many electronic components. It appeared that 4 of the driver transistors were fried.


Having completed this DIY job and seeing the inside components of this fan, I highly recommend only using an OEM replacement fan. (Siemans) This fan is internally well built/engineered and is a very complex component of your car. This Job involved a good bit of labor/time to remove and replace. Do it once, with good parts!

Reviving an old post.
My 2004 4.4l N62 engine is always at 105°C at operating temperature (as per KTEMP on the unlocked cluster). Is this the correct value for these engines?

Thanks

The intravee data from the ibus shows 215-219*F normal summer operating temps for my N62

there are cold climate and hot climate version of the E53, and i think it did not matter which one was shipped where - you could find cold and hot clime cars at the same location...

Yes.

Good thread. I came here because my X5 is running 215 on the highway and a bit warmer around town. On other cars, I'd panic, but this seems normal?????