Engine temp questions

[joeyman00]

This might sound like a dumb question but my previous car never did this.
So in the mornings when it's fairly cold and late at night my Z3 will get up to the normal tempature but as I drive faster around 45-60 mph it will drop to colder engine temp about a notch lower then normal then later it will go back to the middle the normal tempature the car does this all throughout driving is this normal? I've attached 2 pictures the first being the normal tempature it is normally at then second picture is how low it drops then will go back. The car will never go above the normal temp or overheat so that's a good start aha
Image 1: https://pasteboard.co/IfAoaZD.jpg
Image 2: https://pasteboard.co/IfAnS0C.jpg
I'm guessing this is cold air entering the engine since I'm going 60mph but just let me know if this is normal thanks guys

[BimmerBreaker]

Sounds like you need to replace your thermostat

[bluptgm3]

Sounds like you need to replace your thermostat

Sounds like it has failed in open position.
Good time to check belts, pull-ups, and replace water pump.


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[joeyman00]

I think my thermostat works like it should I mean... at other times like 9am to 7pm my car will always hold normal temperature and it only moves at cold tempatures

[BimmerBreaker]

I think my thermostat works like it should I mean... at other times like 9am to 7pm my car will always hold normal temperature and it only moves at cold tempatures

Oh ok.

Let me ask you then, whats wrong with it that is causing it to run cooler on the highway? It is not normal to do that

[joeyman00]

whenever I get above 45mph it starts going down and it will hit the marked point in the picture about a notch down when I hit 60mph on cold mornings and cold nights

[Andy Woods]

That's definately not normal. My 2.5 M54 is rock steady at 12 o'clock no matter what speed I'm going or what the outdoor temp is. The thermostat is there to maintain engine temperature. I don't think it is doing it's job.

[BimmerBreaker]

whenever I get above 45mph it starts going down and it will hit the marked point in the picture about a notch down when I hit 60mph on cold mornings and cold nights

And if it is not a faulty thermostat causing that issue (as you say its not) then what is causing that issue?

[joeyman00]

And if it is not a faulty thermostat causing that issue (as you say its not) then what is causing that issue?

I don't know what else it could be I thought it wouldn't be a faulty thermostat because the thermostat is telling me when the engine is normal

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[BimmerBreaker]

It's a faulty thermostat buddy. Replace it

[joeyman00]

It's a faulty thermostat buddy. Replace it

You thinking water pump and thermostat ? I have the M52 btw also if it's the thermostat, is it ok to drive the car like fast/high rpms when it's reading the colder temp since the readings might be or are wrong

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[BladeRunner919]

100% faulty thermostat. No point asking if you aren't going to believe the obvious answer.

[joeyman00]

100% faulty thermostat. No point asking if you aren't going to believe the obvious answer.

Sorry, wasnt completely sure if he understood my case. I appreciate you helping

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[BimmerBreaker]

You thinking water pump and thermostat ? I have the M52 btw also if it's the thermostat, is it ok to drive the car like fast/high rpms when it's reading the colder temp since the readings might be or are wrong

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The readings are not wrong. The thermostat is bad. Not a bad idea to do water pump at the same time

[joeyman00]

The readings are not wrong. The thermostat is bad. Not a bad idea to do water pump at the same time

This seem right?
https://www.bimmerworld.com/Cooling/...537511580.html

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[Vintage42]

... I thought it wouldn't be a faulty thermostat because the thermostat is telling me when the engine is normal...

The thermostat is not telling you anything.
The ECU is telling the coolant temperature gauge what to display. And it tells the gauge to remain fixed vertical from the point where the engine is warmed up around 170F, to the point where overheating begins around 220F. If the needle is to either side of vertical, then you are being told that the engine is seriously out of normal operating temperature.
My needle was always straight up. But after I installed a digital coolant gauge on the console, I saw the temperature was rising and falling with driving conditions. It ranged from 195F in traffic, down to 170F when coasting down long hills. After installing a new thermostat, the temperature stayed at 206F under all conditions.

[bluptgm3]

You thinking water pump and thermostat ? I have the M52 btw also if it's the thermostat, is it ok to drive the car like fast/high rpms when it's reading the colder temp since the readings might be or are wrong

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Running at colder temperatures is not good. Generally the fuel mixture is on the rich side (washing down the cylinders) and an engine can experience more wear due to excess fuel and cool engine components not being at operating temperature. Fuel mileage suffers and the catalytic converter is at risk by having too much fuel dumped in for too long of duration.

This seem right?
https://www.bimmerworld.com/Cooling/...537511580.html

Depends.
Use the last seven of you VIN in www.realoem.com to determine part number requirements, then go shopping with that/those part numbers.

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[joeyman00]

The thermostat is not telling you anything.
The ECU is telling the coolant temperature gauge what to display. And it tells the gauge to remain fixed vertical from the point where the engine is warmed up around 170F, to the point where overheating begins around 220F. If the needle is to either side of vertical, then you are being told that the engine is seriously out of normal operating temperature.
My needle was always straight up. But after I installed a digital coolant gauge on the console, I saw the temperature was rising and falling with driving conditions. It ranged from 195F in traffic, down to 170F when coasting down long hills. After installing a new thermostat, the temperature stayed at 206F under all conditions.

Is this what im looking for?
2.8l m52 btw
https://www.fcpeuro.com/products/bmw...em-11537511083

im confused finding the thermostat part because this part says 92c (196 F) which is not what you quoted as normal operating temps.

[solimans]

Is this what im looking for?
2.8l m52 btw
https://www.fcpeuro.com/products/bmw...em-11537511083

im confused finding the thermostat part because this part says 92c (196 F) which is not what you quoted as normal operating temps.

Check here Realoem.com. Punch in last 7 of vin...may give some clues...

Looks like it’s grouped with the housing?


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[bluptgm3]

S52s run 88C, non-M E36 sixes run 92C from factory.


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[rf900rkw]

You are being handed information from M54s and M44s. Do not let them mislead you. Your car takes the 88C thermostat in your first link..Both the 4cyl and the later 6 cyl run hotter.

Running at colder temperatures is not good. Generally the fuel mixture is on the rich side (washing down the cylinders) and an engine can experience more wear due to excess fuel and cool engine components not being at operating temperature. Fuel mileage suffers and the catalytic converter is at risk by having too much fuel dumped in for too long of duration.

Incorrect for these cars. The system is closed loop at 14.7:1 as soon as the O2s come online and the airpump shuts off. Less than a minute typically.

[me77]

I also would say faulty thermostat. Remember that the gauge shows 12 o'clock at around 70°C if I remember correctly, but the engine is not at full temperature before something above 90°C.