[924er]

Hey guys,

So few weeks ago I got a code for "improper thermostat function", I was about to go ahead and replace it along with the WP but decided to clear the code and see what happens. That day it was pretty cold so I thought of it possibly being a fluke

The code Hasn't returned in few weeks of daily driving and car drives fun but I noticed my oil temp won't go past 200f with ambient temps of 60-70f. I'm used to seeing 220-250f range

Coolant temps range between 180-220f which seems normal to me.

What you guys think? should I just go ahead replace the thermostat/WP? I don't mind waiting and saving up $ lol

[iqraceworks]

So you are getting a fault saying improper thermostat function (thermostat not working right).....and your oil temp is lower that it is supposed to be (thermostat not working right)..........and you are wondering if you should replace your thermostat?

YES.....it's not working right! 👍

I guess you could always just wait until you get the fault again....but I'm guessing that eventually you will need to replace it.

[TunafishE93]

The coolant temp should be 220-230 when cruising. If you are seeing 180 while cruising then that is not normal. It would go down to 180 in sport driving hard.

[924er]

Originally Posted by iqraceworks

So you are getting a fault saying improper thermostat function (thermostat not working right).....and your oil temp is lower that it is supposed to be (thermostat not working right)..........and you are wondering if you should replace your thermostat?

YES.....it's not working right! 👍

I guess you could always just wait until you get the fault again....but I'm guessing that eventually you will need to replace it.

Originally Posted by iqraceworks

So you are getting a fault saying improper thermostat function (thermostat not working right).....and your oil temp is lower that it is supposed to be (thermostat not working right)..........and you are wondering if you should replace your thermostat?

YES.....it's not working right! 👍

I guess you could always just wait until you get the fault again....but I'm guessing that eventually you will need to replace it.

lol well I was thinking make the code was a fluke because it never came back again

[924er]

Originally Posted by TunafishE93

The coolant temp should be 220-230 when cruising. If you are seeing 180 while cruising then that is not normal. It would go down to 180 in sport driving hard.

Originally Posted by TunafishE93

The coolant temp should be 220-230 when cruising. If you are seeing 180 while cruising then that is not normal. It would go down to 180 in sport driving hard.

Yeah I'm seeing 180-200 max and it's not that cold out.

[924er]

Does the oil cooler send it's own fault? Can't remember if mine said oil or coolant thermostat fault lol

[feuer]

Originally Posted by TunafishE93

The coolant temp should be 220-230 when cruising. If you are seeing 180 while cruising then that is not normal. It would go down to 180 in sport driving hard.

What? You probably miswrote something here.

[feuer]

Originally Posted by 924er

Does the oil cooler send it's own fault? Can't remember if mine said oil or coolant thermostat fault lol

Yes, but it won't say thermostat, so oil temp are within the allowed threshold

[TunafishE93]

No, I pretty sure I wrote it correctly.. I believe he has the N54 so I could be wrong but the N55 has eco mode at 226f, normal at 219f, sport 203f and hard sport at 194f.

I have heard people hitting 180f running hard but I never have, I actually never been under 200f (warmed up) but I don't drive track. I am not sure what conditions and time frame the coolant temps range from 180 to 220 but I run 215 to 225f on the high way.. Around town about the same. Its not normal for the coolant to have that range when just cruising. Thanks.

[924er]

Originally Posted by TunafishE93

No, I pretty sure I wrote it correctly.. I believe he has the N54 so I could be wrong but the N55 has eco mode at 226f, normal at 219f, sport 203f and hard sport at 194f.

I have heard people hitting 180f running hard but I never have, I actually never been under 200f (warmed up) but I don't drive track. I am not sure what conditions and time frame the coolant temps range from 180 to 220 but I run 215 to 225f on the high way.. Around town about the same. Its not normal for the coolant to have that range when just cruising. Thanks.

Originally Posted by TunafishE93

No, I pretty sure I wrote it correctly.. I believe he has the N54 so I could be wrong but the N55 has eco mode at 226f, normal at 219f, sport 203f and hard sport at 194f.

I have heard people hitting 180f running hard but I never have, I actually never been under 200f (warmed up) but I don't drive track. I am not sure what conditions and time frame the coolant temps range from 180 to 220 but I run 215 to 225f on the high way.. Around town about the same. Its not normal for the coolant to have that range when just cruising. Thanks.

Yeah I have an n54. Today I drove around town and let it idle outside my house for 10 min and oil temp was barely hitting 200f. Still no fault codes. My mechanic thinks it's weather related but it's not that cold, I'll say 60f (cold for California) lol

I'll change the tstat/Wp soon but wanted to know if it's a problem to keep driving it

[924er]

Originally Posted by feuer

Yes, but it won't say thermostat, so oil temp are within the allowed threshold

Originally Posted by feuer

Yes, but it won't say thermostat, so oil temp are within the allowed threshold

Ohh I see. Yeah my fault code specifically said "thermostat"... but it's weird it hasn't returned since I cleared the code

[feuer]

Originally Posted by TunafishE93

No, I pretty sure I wrote it correctly.. I believe he has the N54 so I could be wrong but the N55 has eco mode at 226f, normal at 219f, sport 203f and hard sport at 194f.

I have heard people hitting 180f running hard but I never have, I actually never been under 200f (warmed up) but I don't drive track. I am not sure what conditions and time frame the coolant temps range from 180 to 220 but I run 215 to 225f on the high way.. Around town about the same. Its not normal for the coolant to have that range when just cruising. Thanks.

I don't think you did as isn't logical to have lower temperatures, whether oil or coolant, when engine is run hard.

[feuer]

Originally Posted by 924er

Ohh I see. Yeah my fault code specifically said "thermostat"... but it's weird it hasn't returned since I cleared the code

Just keep driving as is. Let that be you troubleshooting process if you aren't able to monitor and log temps via BMW diagnostics tools.

[TheMidnightNarwhal]

Originally Posted by 924er

Ohh I see. Yeah my fault code specifically said "thermostat"... but it's weird it hasn't returned since I cleared the code

It took me so looong before I got a t stat code pop up when mine was defective.

The best way to test let the car heat up the coolant to around 90c. Then hop on the highway. If the temp keeps dipping and dipping then t stat for sure. My temps on highway for coolant would start 80c from the parking lot then drop to 50c.

You can also once it heated up, tigger the rad fan and see if the coolant drops by a lot.

[924er]

Originally Posted by TheMidnightNarwhal

It took me so looong before I got a t stat code pop up when mine was defective.

The best way to test let the car heat up the coolant to around 90c. Then hop on the highway. If the temp keeps dipping and dipping then t stat for sure. My temps on highway for coolant would start 80c from the parking lot then drop to 50c.

You can also once it heated up, tigger the rad fan and see if the coolant drops by a lot.

Originally Posted by TheMidnightNarwhal

It took me so looong before I got a t stat code pop up when mine was defective.

The best way to test let the car heat up the coolant to around 90c. Then hop on the highway. If the temp keeps dipping and dipping then t stat for sure. My temps on highway for coolant would start 80c from the parking lot then drop to 50c.

You can also once it heated up, tigger the rad fan and see if the coolant drops by a lot.

Oh ok so i gotta log the coolant on MHD because my cluster shows no coolant gauge. I'll test it out.

Is it bad if I keep driving it like this ? I seen ppl wanting low coolant temps of 180 by bypassing the oil cooling thermostat..

[924er]

Originally Posted by feuer

Just keep driving as is. Let that be you troubleshooting process if you aren't able to monitor and log temps via BMW diagnostics tools.

Originally Posted by TheMidnightNarwhal

It took me so looong before I got a t stat code pop up when mine was defective.

The best way to test let the car heat up the coolant to around 90c. Then hop on the highway. If the temp keeps dipping and dipping then t stat for sure. My temps on highway for coolant would start 80c from the parking lot then drop to 50c.

You can also once it heated up, tigger the rad fan and see if the coolant drops by a lot.

Originally Posted by feuer

Just keep driving as is. Let that be you troubleshooting process if you aren't able to monitor and log temps via BMW diagnostics tools.

I'll try the MHD log, I think I seen coolant as one of the parameters in Fahrenheit

[TunafishE93]

Guess my car is not logical, these are two pulls I ran back to back. Before starting the pulls car was running 215f coolant. Then during went up to 223f. Then the illogical part it went down to 198f between pulls (about 20 seconds between pulls). The second pull I topped at 219f then went down again after.

This was after running between 215 and 225f for an half hour (cruising). So yes my car went down in temp driving hard. Even my peek temp went down between the first and second pull.

https://datazap.me/u/tunafish389/log...=0&data=4-6-15

[iqraceworks]

I'm pretty sure that when the car figures out it's getting driven hard (load, rpm, boost)....it will run the water pump more frequently and/or open the thermostat more. It's not just a straight temp bases system.

[JFolt]

My N55 335i has also been running a bit cool lately. I used to always be just less than mid point on the oil temp gauge, about 240F. Then a few months ago my coolant expansion tank cracked while driving. Drove home about 2 more miles, parked car, replaced tank, refilled coolant and now the oil is regularly around 220-230F. I think either the coolant T-stat or oil cooler t-stat are stuck partially open. Coolant temps are always steady around 101C and oil gets to about 95% of where it should be so I'm not too worried about it for now. Been driving like this for about 3 months now without any dash warnings.

And FYI, when researching this a few months ago I did read that the N55 is designed to run hotter during highway cruising. It improves fuel economy... Less liquid fuel going into cylinder, hence less cooling from gasoline or something like that. So on the flip side, it will run cooler when being driven hard... for those with oil coolers, that will open up and cool the oil directly. Also the added gas being injected into the cylinder will naturally cool the cylinder walls between combustion cycles.

[Dabrwright]

Why are people still confusing coolant temperature with oil temperature?
They obviously are related but are not interchangeable!

[fazman]

Originally Posted by 924er

Hey guys,

So few weeks ago I got a code for "improper thermostat function", I was about to go ahead and replace it along with the WP but decided to clear the code and see what happens. That day it was pretty cold so I thought of it possibly being a fluke

The code Hasn't returned in few weeks of daily driving and car drives fun but I noticed my oil temp won't go past 200f with ambient temps of 60-70f. I'm used to seeing 220-250f range

Coolant temps range between 180-220f which seems normal to me.

What you guys think? should I just go ahead replace the thermostat/WP? I don't mind waiting and saving up $ lol

So I got a new WP+Tstat kit from FCPEuro and had that install around Oct 2019. Like you I was also getting weird codes for the thermostat intermittently. The code was 2EF4 i believe. My oil temps were also unusually low of about 200F.

Keep in mind my car is originally from NY/NJ and is no stranger to single digit F or even negative F temps. Cali cold of 60F shouldn't be an issue at all

A Tstat that fails open is not really an issue, if it failed closed that would be a problem. I believe these also have a bypass hose too? I was able to see the car reach its normal 235F or 240F oil during a day time run with no codes.

[MightyMouseTech]

Originally Posted by feuer

I don't think you did as isn't logical to have lower temperatures, whether oil or coolant, when engine is run hard.

Yes it is logical. That is how they are designed to operate.