Oil temperature is wrong!!

Vetracr

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I have been chasing a high oil temperature problem when I run track days my 2010 3.0si N52 6 speed. I have observed 165 degree C + oil temps on hot days at the track. First I added a Setrab 19 row oil cooler in the factory position in front of the passenger side wheel well. It was vented, baffled etc. so the design and installation was correct, still no difference in oil temp readings. Something was definitely amiss as this should not happen. I finally went all in to solve problem. I replaced Setrab cooler with a large Mishimoto oil cooler than runs from frame rail to frame rail located just behind the lower grill opening. Using the ports on the oil temperature thermostat housing I installed an oil temperature gauge on the line coming from the oil cooler. I also installed an oil pressure gauge on the port measuring the oil temp of the oil coming from the oil pump. I also installed a water temperature gauge on the water temp feed line to the water pump.


Gauge installation attached to cup holder for easy removal
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Oil temp and oil pressure gauge sender installation


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Water temperature gauge sender installation
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Overall view of sender installation
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View from backside of gauge mount showing disconnects to remove gauges for non track days
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Now that I had tools to measure REAL oil temp I ran a track day. At 7000 rpm in 4th gear on a 90 degree day I was reading 165 degrees C (329 degrees F) on dash oil temp gauge. Oil temperature gauge measuring oil exiting oil cooler was 210 degrees F!!!!! Water temperature under the same conditions was 235 degrees F. Clearly dash gauge is wrong or is computer manipulated temperature. The BMW oil temperature gauge is in the pan. The oil pump draws oil from the pan and then compresses it to 70 psi adding more heat to the oil. No oil cooler, no matter how efficient is going to cool oil from 329+ degrees F to 210 degrees F. From driving on the street it is also clear that the dash oil temp gauge is dampened to have a very slow response. Bottom line is that you can't rely on dash oil temperature gauge for an accurate reading.
 

fmorelli

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Correct me if I'm wrong but weren't you having limp mode issues? If so the DME thinks things are too hot, right? What's your next step? I'd be curious what the actual BMW sensor is putting out, voltage-wise.

Filippo
 

Vetracr

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Correct me if I'm wrong but weren't you having limp mode issues? If so the DME thinks things are too hot, right? What's your next step? I'd be curious what the actual BMW sensor is putting out, voltage-wise.

Filippo
Filippo
I have an N52, so no turbo, no limp mode. My test alleviates my worry about the oil temp as the real oil temp going to the bearings is 210 degrees F. The water temp of 235 also is within reason. Right now the oil temp issue is on the back burner as I cooked my front caliper seals so its brake overhal time.
 

Vetracr

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Filippo,

Attached are the power correction tables BMW applies as a function of water temperature and oil temprature. In both cases power is reduced up to 10% as a function of temperature. You can understand my concern about both temperatures as in both cases power is lost when you need it most
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fmorelli

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Filippo,

Attached are the power correction tables BMW applies as a function of water temperature and oil temprature. In both cases power is reduced up to 10% as a function of temperature. You can understand my concern about both temperatures as in both cases power is lost when you need it most
Ok say you don't have limp mode, but you have power reduction occurring? Do you have any plans to ferret out what's going on with the BMW temperature measurements?

Filippo
 

fmorelli

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This is another example that we often experience, where we throw hardware at a problem, and then end up with measurements that tell us something else. In the case, further exacerbated by magic mystery BMW gauge data.

BTW it might be worthwhile to have a conversation with @[email protected] about how an AIM data acquisition system could benefit your track driving. He runs them in his and his client's race cars, knows a lot about how to use them, et cetera.

Filippo
 

fmorelli

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Just that the needle display corresponds to what the DME says the temperature is (during normal conditions).
So with that said, @Vetracr could buy an Vgate2 BT OBD2 dongle, Torque app (why do I suspect he already has this stuff) and see if Torque gets a different value than the gauge shows. This would at least separate a discrepancy from the gauge side and the sensor side.

Filippo
 

Vetracr

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Ok say you don't have limp mode, but you have power reduction occurring? Do you have any plans to ferret out what's going on with the BMW temperature measurements
Filippo

Filippo
Any reading from the CAN bus will be from the computer not from the pan temperature gauge. The computer is running the raw temperature data through an unknown algorithm. When I get brakes
rebuiit I"'ll contact local tuner to see if I can learn more about what goes on with corrections.

Larry
 

fmorelli

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I understand that, because the sensor doesn't put the data on the canbus. It's whichever computer handles that sensor. Hence the manipulation. My point was just separating the gauge value (if the gauge has an issue) versus what the DME is kicking out.

Filippo
 

Vetracr

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I understand that, because the sensor doesn't put the data on the canbus. It's whichever computer handles that sensor. Hence the manipulation. My point was just separating the gauge value (if the gauge has an issue) versus what the DME is kicking out.

Filippo

Filippo,

My understanding is that the oil temp, oil condition, oil level sender assembly has a built in diagnostic. If there were a problem I would expect to see an error message or code set. Even if I could access the oil temp sensor alone without knowing the resistance vs. oil temp table values it wouldn't help much and that is assuming the temp sensor is a resistor.

Larry
 

NoQuarter

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As an aside... this is supposedly also how the oil level is determined for the oil level display.

Based on how long it takes to heat the oil to a specific temp determines the volume of oil that must be in there.

But... this doesn't match with getting a warning to add a quart of oil in the middle of a highway drive.
 
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