Preventing Oil Leaks

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04-02-2014, 03:24 PM

#31

gwf545

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My Ride: 2015 535D M Sport

Quote:

Originally Posted by ncsugrad2006

The thermostats are called 105* stats.. I guess maybe that is their "wide open" temperature? Mine stayed just over 100*C on the highway but would get hotter than that otherwise (when AC was on + hot water). I got a 95*C thermostat now to bring it down just a tad

BMW WAHLER Thermostat with Housing and O-Ring (105 deg. C) 11537586885 - RM European Auto Parts

Also, even BMW's own documentation on the N62 engine shows temps that high being normal and "more economical". It has several different modes, the highest temp/most economical one being in the 220 range. For the performance modes the computer can bring the temps down

It still didn't make sense to me that the thermostat would be opening at that high a temp or the engine normally runs that hot, so I dug out my Bentley service manual and found that 105C is the FailSafe thermostat opening temp in the event the ECU or thermostat develops a fault and doesn't open it electrically at the proper operating temp.

I have enabled the hidden menu temp gauge several times over the past few weeks and the hottest I ever got was 96C with a typical range of 83C to 93C. Now that makes sense and pretty much blows away a high heat explanation. At least unless you have some sort of fault that is causing it to run hotter.

I'd also seen the 105C engine operating temp claim on other message boards and based on personal experience and the service manual, it's simply incorrect. Also there is no source for a lower temp opening thermostat, I checked with Wahler.