TDF10

I don't recall the fan kicking on during the bleeding process. I always though that air in the system would cause overheating (not overcooling).

seanjordan20

For the most part overheating is a symptom but I'm just trying to figure it out how is the issue even possible. With 2 new OE thermostats and a new pump. Were you having this issue before you did all the work?

The only thing I can come up with is an open thermostat or cooling fan on continuously which is a reason why I said bleed it again to see if the fan cuts on. If the fan is not cutting on then there's an issue with the thermostat. Your thermo is not mapped so no plug or sensor to worry about. You could even remove the thermo and throw it in a pot of boiling water to see if it opens then cool it down to see if it's closing. That will at least let you know if it's operating correctly. Just trying to think of some troubleshooting ideas at this point.

TDF10

I wasn't having this issue prior to doing the work. The car heated up quickly and stayed right at the normal
operating temperature. I only did this work as preventive maintenance which is now causing me this headache. One thing I just realized, do our cars even have a coolant temperature gauge or is that the oil temperature gauge on the right side of the instrument cluster? don’t have my car in the garage (getting windshield replaced) otherwise I’d check myself.

seanjordan20

Yes it's an oil temp gauge. You can either plug up an OBD2 reader or on the odometer screen via secret menu to see the coolant temp.

seanjordan20

Look at this to see how to get to the hidden menu.

TDF10

In theory though, my engine oil temperature should run parallel (not necessarily the same temperature but same trajectory) with coolant right? It seems even more odd to me that the oil temperature would be fluctuating so significantly...

seanjordan20

Not necessarily because the temps are controlled separately. Your coolant has a round about max temp due to the thermo set temp. This keeps the engine cooled to maximum efficiency. Then you have the oil temp which is controlled by its own cooling thermo for optimum lubrication. They both have their own temp sensor and cooler.

If I'm not mistaken normal coolant temp should be around 206* and normal oil temp should be between 240*-250*. BMW is known for running the engines at hotter temps for optimum performance but both temps are maintained separately.

TDF10

I guess what I'm asking is whether it makes sense that oil temp would be fluctuating significantly? Once oil gets hot, I have to believe it's harder to cool than straight coolant right? If the gauge was coolant temp, I could understand the fluctuations. Since it's oil temperature, maybe it is an issue with my battery that is causing some weird readings.

seanjordan20

I don't see how it would be a battery issue when you never did anything with the battery. Your battery supplies power to the car. If your battery was undercharge or going dead a temp gauge is the last thing I would be looking at to let me know I have a battery issue. At this point I think you need to get some hard temp readings and codes. Also do some troubleshooting to start eliminating possible issues. You're saying you weren't having the issue before working on the car so what you did caused the issue you're having if it is an issue at all. I think the steps I've told you to take are good steps to start troubleshooting and will get you to what your actual issue is. Perform them and come back with the results. I need hard temps, codes and results to further assist you as of now I'm only seeing speculations. If you think it's a battery issue test the battery and alternator to see the voltage it's at and charging voltage. I need numbers until then there is no other advise I can give.

TDF10

I'll give this a shot as soon as I get the car back from the windshield replacement folks. As for the battery, I noticed it was starting to weaken. I hooked it up to a tender and it wasn't able to fully charge overnight. Since it's the original (2014), I'm speculating that it's probably time for a change. I know that sometimes, weak batteries can cause a host of issues related to vehicle electronics, sensors, etc. Thanks for all the good insights. Fingers crossed.