[tctic]

Today I was monitoring the water temperature of the engine using the hidden on-board computer menu 07.00. It seemed that from a cold start, it will slowly reach 90C then to 96-97C.

And then I finally got a chance to red line the engine to mid-6000rpm. Suddenly, the temperature reads 85C. After a while, it slowly heats up to 95-97C again. Quite interesting. I guess this is why there's no water temperature gauge in the E90 or it will start flucuating all the time.

But if BMW wants to satify those who miss the gauge because they can not tell when the engine had warmed up yet, they should add a function for drivers to check. Maybe a menu within the On Board Computer.

[visor]

Originally Posted by tctic

But if BMW wants to satify those who miss the gauge because they can not tell when the engine had warmed up yet, they should add a function for drivers to check. Maybe a menu within the On Board Computer.

In order to tell whether the engine is warmed up yet for high revving sheenanigans, the water temp is an OK indicator, but not as good nor is it a substitute for the gold standard - oil temperature.

[E90Fleet]

N52 enige runs a variable water temp depending on driving conditions.

Higher temp gives better fuel consumption, but lower temp gives better acceleration. This is why you saw the temp drop when you stareted revving a lot.

[E90Fleet]

Also, as said the water temps doesnt give a indication of when the engine is ready, since with the electric waterpump the engine can heat up the water very quickly, well before the engine is trully ready

[Broken1]

I use an estimated 5 mins of driving until my engine is warmed up. I do believe however, that the diesel engine warms up faster than the petrol engine...

Interesting note on the water temp though. Might be getting a 325i into the family soon, so I'll check that out when I get into a petrol E90 :-)

[deutsch100]

How do you access menu 07.00 to see the water temp? I have the OBC, but no Navi. Is this another "I have Navi", so I'm better feature?

[billgti]

Originally Posted by tctic

Today I was monitoring the water temperature of the engine using the hidden on-board computer menu 07.00. It seemed that from a cold start, it will slowly reach 90C then to 96-97C.

And then I finally got a chance to red line the engine to mid-6000rpm. Suddenly, the temperature reads 85C. After a while, it slowly heats up to 95-97C again. Quite interesting. I guess this is why there's no water temperature gauge in the E90 or it will start flucuating all the time.

But if BMW wants to satify those who miss the gauge because they can not tell when the engine had warmed up yet, they should add a function for drivers to check. Maybe a menu within the On Board Computer.

first, as others have said, your water temperature goes up much quicker than your oil does and whether you should rev the engine depends on how warm the oil is, not the water. my older vw had an oil temperature gauge and it would reach it's normal operating temperature about 10 minutes AFTER the coolant needle reached the middle.

second, the fact that your water temperature fluctuates is entirely normal for every car. the gauge you see in other cars where the needle is always at the middle is pretty much a basic gauge that registers cold, normal and overheating. it won't show the normal fluctuations in accelerating. that's probably the reason why bmw decided to do without it. only a few cars like the mitsubishi evo has an accurate coolant gauge where you can actually see it move as opposed to staying in the middle.

[E90Fleet]

Originally Posted by billgti

second, the fact that your water temperature fluctuates is entirely normal for every car. the gauge you see in other cars where the needle is always at the middle is pretty much a basic gauge that registers cold, normal and overheating. it won't show the normal fluctuations in accelerating. that's probably the reason why bmw decided to do without it. only a few cars like the mitsubishi evo has an accurate coolant gauge where you can actually see it move as opposed to staying in the middle.

Most cars stay within a few degrees of their set temperature.

The N52 is the first production BMW engine that operates at a range varying over 30 Degrees Celcius. This is possible due to the electric waterpump and ECU controlled thermostat

[tctic]

Originally Posted by deutsch100

How do you access menu 07.00 to see the water temp? I have the OBC, but no Navi. Is this another "I have Navi", so I'm better feature?

No, non-iDrive cars have it too. Even the E46 has all these hidden menus.

To instructions to unlock these hidden menu, read this:
http://www.e90post.com/forums/showthread.php?t=4135

[chinna_n]

This is a old thread, but relevant thread. My 2007 328i water temp is alarming to me. I recently bought this used. After two weeks of use, I connected scangauge to monitor parameters. I was monitoring water temp initially it is settled around 194-205F, then I was stuck in traffic for 15 min(very slowly moving), the water temp went upto 228F. There is no error indicator in the dash. But later traffic started moving, then temp dropped to 194F.

Is this normal? Is this temp acceptable?

Thanks for help!

[Wires]

Normal. You need air flow to cool the engine. With only the fan pulling in air, you get a lot of heat soak from the engine. Once the car is moving, the underhood temperatures drop a lot.

[chinna_n]

But this is winter. If in winter 15min of traffic Jam generates such high temps because of lack of airflow, how it would be in summer?

Does the computer throw any error codes if Fan is not working?

[Wires]

Probably slightly higher in summer. That engine compartment is stupid cramped. You get a lot of heat accumulating under the hood without the car moving.

You should get a code if the fan stops.

[chinna_n]

Ok. I did some testing this morning(parked in front of garage and tested). Ran the engine at approx 2500RPM for 10 min after drive. The temp reached ~224F when radiator Fan started. But when I kept increasing the Engine RPM to 2800 temp touched 236F. This is when radiator Fan speed increased and temp dropped to 224F pretty quickly. But during fan high mode, even increase in engine RPM to 3200, did not increase temp above 224F.

Temp range seems rather wide, ~195-236F.

So, is this expected? Fan only kicks on at such high temp?

I pulled my other car, after a drive I tested that, temp is in very short range ~180-188F irrespective of RPM and load. It was very consistent.

Thanks for all the help!

[mike3000fl]

the desired temp the car seeks will change based on the situation. fuel economy vs performance. there is no set temp for all conditions.

the water pump runs independent of RPMs, since it is electric, the car varies the speed to keep the optimum temp for what you are doing.

[Wires]

+1 Engine is more efficient at higher temps (but you lose power). 195F is the balance point.

If you're idling in traffic, it most likely will allow for a hotter operating temp to reduce emissions.

[chinna_n]

But I was wondering if anyone seeing similar temps like mine?

I am worried about this 236F. I am planning for long drive over this weekend, just want to make sure it is not something unusual.

Thanks

[Blackhawk36]

Heat Management
The engine control unit of the N54 engine controls the coolant pump according to
requirements:
• Low output in connection with low cooling requirements and low outside
temperatures
• High output in connection with high cooling requirements and high outside
temperatures
The coolant pump may also be completely switched off under certain circumstances,
e.g. to allow the coolant to heat up rapidly during the warm-up phase. However, this only
occurs when no heating is required and the outside temperature is within the permitted
range.
The coolant pump also operates differently than conventional pumps when controlling
the engine temperature. To date, only the currently applied temperature could be
controlled by the thermostat.
The software in the engine control unit now features a calculation model that can take
into account the development of the cylinder head temperature based on load.
In addition to the characteristic map control of the thermostat, the heat management
system makes it possible to use various maps for the purpose of controlling the coolant
pump. For instance, the engine control unit can adapt the engine temperature to match
the current operating situation.
This means that four different temperature ranges can be implemented:
• 108°C ECO mode
• 104°C Normal mode
• 95°C High mode
• 90°C High + map-thermostat mode
The control system aims to set a higher cylinder-head temperature (108°C) if the engine
control unit determines ECO (economy) mode based on the engine performance.
The engine is operated with relatively low fuel consumption in this temperature range as
the internal friction is reduced.
An increase in temperature therefore favors slower fuel consumption in the low load
range. In HIGH and map-thermostat mode, the driver wishes to utilize the optimum
power development of the engine. The cylinder-head temperature is reduced to 90°C for
this purpose. This results in improved volumetric efficiency, thus increasing the engine
torque. The engine control unit can now set a certain temperature mode adapted to the
respective operating situation. Consequently, it is possible to influence fuel
consumption and power output by means of the cooling system.
The temperatures specified only ever represent a target value, the attainment of which is
dependent on many factors. These temperatures are first and foremost not attained
precisely.
The consumption-reducing and power increasing effects arise in each case in a
temperature spectrum. The function of the cooling system is to provide the optimal
cooling output according to the boundary conditions under which the engine is being
operated.

[chinna_n]

Thank you BlackHawk! This is really helpful info.
So 226 F is for Eco mode.

But I guess temp is not very tightly controlled. That may be the reason why temp went up 236F before Fan started in high speed mode to bring it down to 224F(close to Eco Mode).