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General E46 Forum
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Old 01-09-2013, 06:28 PM   #61
shanneba
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Quote:
Originally Posted by leetoranges View Post
I drive like 20 miles to work, i'm kind of on the fence about my thermostat,
Idle/city driving avg =90-92, but goes as high as 96 under stop and go traffic, highway it stays at 90/91 but the main concern of mine is, when i pass someone, the temp goes to 84, but after it slowly goes back up to 90, when i go back to cruising speed.Would 84 be too low?
No, 84 C is not too low when passing, if your rpms went past 3000 or the engine load was high the DME applies 12v to the thermostat to heat the wax element and allow the thermostat to open more.

The BMW E46 thermostat is variable, it can operate between 80C and 110C based on engine monitored variables.

http://www.bmw-planet.com/diagrams/r.../e46/index.htm
Function of the characteristic map thermostat
The characteristic map thermostat is designed such that it opens (engine inlet) at a coolant temperature at the thermostat of 103C without intervention of the integrated heating system. Due to the coolant heating up in the engine, a temperature of approx. 110 C is measured at the point the coolant flows out of the engine (installation location of coolant temperature sensor for DME and instrument cluster gauge). This is the operating temperature of the engine, at which the characteristic map thermostat begins to open without control intervention.
In the event of control intervention by the DME control unit, power (12 V) is applied to the heating element integrated in the thermostat. Heating the expansion element means that the thermostat now opens at lower coolant temperatures than would be the case without the additional heating function (thermostat control range: approx. 80 C - 103 C).

This characteristic map is determined by the following factors:
Engine load
Engine speed
Vehicle speed
Intake temperature
Coolant temperature

If the coolant temperature exceeds 113C at the engine outlet, the heating of the characteristic map thermostat is activated by the DME irrespective of the other parameters.
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Old 01-09-2013, 07:14 PM   #62
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jfoj,

Outside temp has been 60-70F lately and I been monitoring the coolant temps on torque pro for the past week to make sure everything is ok. I don't have any debris or blockage. I just did coolant system PM and replaced radiator, expantion tank, all coolant hoses, temp sensor, thermostat and water pump. I did check both the aux and mechanical fans are working after everything was done.

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Old 01-10-2013, 08:27 PM   #63
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Wow I'm really glad you started this thread. I seemed to be a prime candidate. I had noticed my mpg drop a bit. I'm sure the cooler temps have something to do with it but I'm down an average of 3-4 mpg over the last year or so. I also noticed a bit of yellow goo under the oil cap for the first time during my last oil change (7500 intervals). From what I understand if the crankcase temp isn't getting hot enough it may not adequately burn away excess moisture, causing this.

Anyways, I pulled up the temp reading on my dash before I left for work. Its about 25 minute ride home. Outside temp was about 40 degrees. Here are my observations:

First 10 Mins - Two lane road with several stop lights. Most of this time was spent warming up. By the time I left this road and merged onto the highway I was at 75 (which I should point out is also when the temp gauge hit 12 o'clock indicating normal operating temp).

Next 10 Mins - All highway, cruising about 70 mpg. raised from 75 to 86 but never went any higher. Jumped between 85 and 86 a few times but that's it.

Next 5 - Back roads to my house, a few stops lights/signs - Continued to stay under 86. Went down to 84 a couple of times but did not fluctuate much.

Its pretty apparent that its time for a new one based on what I read in this thread. The age of the tstat is unknown. The engine and most of what's attached to it was replaced at 70k miles by BMW, but I can't say for sure if the tstat was done as well. Every other piece of the cooling system was mint though I have replaced the WP, Exp tank, belts/pullys, and flushed the coolant a couple times. If it was replaced it has 65k miles. If not its likely original with 135k. Either way, its getting replaced very soon! Thanks jfoj for posting this and to all those who contributed!
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Old 01-10-2013, 11:07 PM   #64
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I'm really glad I found this thread, I think my t-stat is toast.

I have a 328i with M52 engine which I'm not sure is relevant, but most in this thread have a 325/330 with m54. Can anyone comment if the engine temps should be the same between m52 and m54?

I have a 20 mile commute 90% highway. Ambient temperates were 40F today and my OBC peaked at 78-80C and never went above that for the 20 minutes I was on highway. Once I got home and parked I let the car idle for a few minutes and it went up to 84C. Temp gauge has always been DEAD center (never under or over) and it usually takes <5 minutes to reach center from a cold start.

For what it's worth, my MPG has remained relatively constant at 26-28MPG.

T-stat was replaced when I bought the car 6 years ago, while other cooling parts have been replaced more recently. Anyone else think it's time for a new one?
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Old 01-10-2013, 11:27 PM   #65
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I believe the 328 may be the same basic concept as the 325/330?

Maybe some 323/328 owners can chime in and we will be able to see if their temps run in the low 90C range as well.

I would guess the 328 should also run in the 95C range typically?
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Old 01-10-2013, 11:36 PM   #66
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i remember back in summer it got up to 100-102, but thats the highest ive seen it, its in the 20s in the morning here so ill see what it is on my drive tomorrow and report back
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Old 01-10-2013, 11:52 PM   #67
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I am thinking these cars may start to run in the very low 100C range during peak temps in the Summer?? This may also be why there is very little tolerance between an engine cooling and an overheat along with the buffered temp gauge.
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Old 01-11-2013, 12:06 AM   #68
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Also just added Coolant Snitch info in first post as it offered more info on the buffered thermostat and is a good add on overheat warning for E46 owner.

http://www.zhpregistry.net/Tech/CoolantSnitch.aspx

I have no affiliation this person or product, but many may find it useful.
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Hidden OBC Menu - Check Voltage, Temps, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

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Old 01-11-2013, 06:12 AM   #69
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Quote:
Originally Posted by verb View Post
I'm really glad I found this thread, I think my t-stat is toast.

I have a 328i with M52 engine which I'm not sure is relevant, but most in this thread have a 325/330 with m54. Can anyone comment if the engine temps should be the same between m52 and m54?

I have a 20 mile commute 90% highway. Ambient temperates were 40F today and my OBC peaked at 78-80C and never went above that for the 20 minutes I was on highway. Once I got home and parked I let the car idle for a few minutes and it went up to 84C. Temp gauge has always been DEAD center (never under or over) and it usually takes <5 minutes to reach center from a cold start.

For what it's worth, my MPG has remained relatively constant at 26-28MPG.

T-stat was replaced when I bought the car 6 years ago, while other cooling parts have been replaced more recently. Anyone else think it's time for a new one?
You might be the perfect example of what OP meant by a soft-failing stat.

Unless, you're like me, and drive on the highway in 3rd gear sometimes.

Otherwise, I think you're running on the cold side...although, I guess I should say that that 40 degree would cool things considerably and you are in the 'normal' zone still.

I'd look to see if your temp needle sits just left of dead center on the highway...bet it does.
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Old 01-11-2013, 09:23 AM   #70
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Originally Posted by dmax View Post
You might be the perfect example of what OP meant by a soft-failing stat.

Unless, you're like me, and drive on the highway in 3rd gear sometimes.

Otherwise, I think you're running on the cold side...although, I guess I should say that that 40 degree would cool things considerably and you are in the 'normal' zone still.

I'd look to see if your temp needle sits just left of dead center on the highway...bet it does.
Even in 40F weather, it should reach 93-95C. Over the holiday, I was driving in Nashville at about 20F and I was still reaching normal temps. I do wonder if the M52 is slightly different though. Are the M52 and M54 thermostats the same part number?
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Old 01-11-2013, 10:55 AM   #71
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RealOEM.com shows the same part number for the 320, 323, 325,328 and 330 engines:

http://realoem.com/bmw/partxref.do?part=11537509227

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Last edited by shanneba; 01-11-2013 at 10:59 AM.
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Old 01-11-2013, 10:56 AM   #72
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Originally Posted by WDE46 View Post
Even in 40F weather, it should reach 93-95C. Over the holiday, I was driving in Nashville at about 20F and I was still reaching normal temps. I do wonder if the M52 is slightly different though. Are the M52 and M54 thermostats the same part number?
dmax, I'll double check, but I'm pretty sure the needle is dead center. I think I might be running at the extreme lower end of what the buffered gauge considers normal. If the ambient temperatures were slightly colder, perhaps the needle would be off center.

WDE46, I just checked realoem and it gave the same part number, 11537509227, for an M52 328 and m54 330. I guess they are the same.

Regardless, I think it's time for me to change my thermostat.
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Old 01-11-2013, 11:03 AM   #73
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Originally Posted by verb View Post
dmax, I'll double check, but I'm pretty sure the needle is dead center. I think I might be running at the extreme lower end of what the buffered gauge considers normal. If the ambient temperatures were slightly colder, perhaps the needle would be off center.

WDE46, I just checked realoem and it gave the same part number, 11537509227, for an M52 328 and m54 330. I guess they are the same.

Regardless, I think it's time for me to change my thermostat.
it's probably time to change everything
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Old 01-11-2013, 12:21 PM   #74
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Checked out my temp this morning while driving...weather was freezing 32f. Temp on high way was from 75-80. Highest it got in stop and go was 88 for a brief second...and quickly went back down to high 70s...a little low, I'm figuring its the cold weather...

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Old 01-11-2013, 01:11 PM   #75
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Originally Posted by jfoj View Post
I believe the 328 may be the same basic concept as the 325/330?

Maybe some 323/328 owners can chime in and we will be able to see if their temps run in the low 90C range as well.

I would guess the 328 should also run in the 95C range typically?
I have a 323i, my dummy gauge is stays exactly at 12 oclock when warmed up and I hit 100 once fully warmed up at steady speed on freeway. Whenever I accelerate it drops to around 96. I looked in the bentley manual and it says Coolant temperature working value K -bus 100C (212F). This is exactly what mine runs at.
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Old 01-11-2013, 01:15 PM   #76
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Checked out my temp this morning while driving...weather was freezing 32f. Temp on high way was from 75-80. Highest it got in stop and go was 88 for a brief second...and quickly went back down to high 70s...a little low, I'm figuring its the cold weather...

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No. You need to change your them.
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Old 01-11-2013, 01:15 PM   #77
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If your car won't go to 93-96C you need a new thermostat.
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Old 01-11-2013, 01:47 PM   #78
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Old 01-11-2013, 02:11 PM   #79
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And, as I was driving at 40 mph in 40 degree F temps in the rain...it read 90.

I think rain would aid a bit in the cooling efficiency of the radiator, but I'm just guessing.
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Old 01-11-2013, 04:46 PM   #80
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