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DIY: Do It Yourself
Post here to share or improve your wrench turning skills! All BMW E46 DIY tips, tales, and projects discussed inside. Learn to work on your car and know the right BMW parts you will need!

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Old 01-21-2014, 02:09 PM   #21
MonkeyMouse
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I just started having this problem myself. I'm almost identical to the op in everything hes stated except a new radiator. Using my ultragauge my coolant temps are sitting between 204-208 deg F. Is that normal or a little high? I'll try replacing the sensor when the weather warms up if no other ideas come to front.
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Old 01-21-2014, 02:14 PM   #22
Sigrid7993
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How long ago did you replace your expansion tank? Did you buy oem or aftermarket?

Perhaps there are some aftermarket expansion tanks that aren't manufactured to the tolerances that the coolant level sensors are expecting?

What naggs me is that this problem only occurs in the winter. Which really makes me think there is either an air bubble inside the hvac unit somewhere; or there is a minor leak that is allowing air in. Granted I haven't needed to top off the coolant since I re-did the system 18 months ago..
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Old 01-23-2014, 04:00 PM   #23
mjdehlin
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I've been experiencing a similar issue with an intermittent low coolant light. My ET is topped up to the correct level and I've been checking the coolant level almost daily and I see no loss of fluid.

The light comes on shortly after the temp gauge hits the 12 o'clock position (75 C) I've been using the gauge cluster computer to read the operating temps in menu 7.0 and it seems to be a little low (88-90C) when fully warmed up. The temps here have been extremely cold (-10 to -25 deg F ) ..could it be possible the the 2-5 degrees lower than the optimal 92-95C deg range is because of the extreme cold? I also noticed a bit of the yellow 'mayo' on the underside of my oil fill cap indicating some condensation build up.

Lately the heater seems take longer to warm up than usual even though the engine has warmed up to the 12 o'clock position. It's as if the valve that controls coolant flow to the heater core is not opening right away because I'll suddenly see the needle drop below 12 o'clock as cold coolant rushes into the system and then warm air will finally begin to blow from the vents. Any chance this delayed opening of the coolant valve to the heater core could be due to the extreme cold temps outside?

Would any of these symptoms point to a soft failing thermostat?

Once it warms up a little outside I plan to swap the coolant level sensor with the washer fluid sensor (since they are the same part) and see if there any difference in the behavior of the low coolant light.

In the spring I plan to fully replace the entire cooling system since I'm pushing over 130,000 miles on what I believe to be all original cooling system hardware. (Thanks to Mango for the excellent thread on the subject)
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Old 01-24-2014, 01:36 PM   #24
Sigrid7993
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Quote:
Originally Posted by mjdehlin View Post
I also noticed a bit of the yellow 'mayo' on the underside of my oil fill cap indicating some condensation build up.
I'm 99% sure this is related to a failing/clogged CCV valve - take alook at this DIY. http://www.e46zone.com/forum/topic/4...ve-m54-engine/
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Old 02-07-2014, 01:08 PM   #25
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I have something that I would like other people who are experiencing this problem to try:

I've noticed that whenever the coolant level light comes on, if I change the cabin heat to 91f (i know, I open the sunroof), the coolant level indicator light will turn off within 20-30 seconds without fail. In my case, the coolant thermostat indicator doesn't change from it's dead center position. I'm interested if other people with this problem can reproduce this.
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Old 02-08-2014, 03:10 AM   #26
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From the pictures I have seen, your ET is overfull, the top of that stick should be even with the rim of the ET when cold. That's from the owners M. once that bottom mark (overfull mark) is at the rim you can keep adding and the stick can't keep rising up.

It only says overfull once and in one way no mater how overfull it is. Check that immediately.

Two, majorly an air bubble is not going to cycle through your expansion tank trigger a low coolant light and go back into the engine. They are actually designed to trap any small bubbles that are in the system in the et, if there are little bubbles, you run the car till normal temp then let it cool completely and all of a sudden there's a lot less coolant in your ET because the air is there instead. Major bubbles can Block the tstat and cause an over heat tho. Not the issue here.

Third normal opreating temp is about 84 to 98 c. Your tstat, if it is a stock temp, is set for 97c. I have heard BMW says 70 - 115. That's really extreme tho 115 and I would be freaking out.

Look up the instrument cluster tests. Real time digital water temp as you drive. Keep an eye on that Reallly nice feature.

I would put my money on the sensor. That coolant level sensor i believe is a magnet on/in the stick maybe it fell out? Or its just bad. Or maybe I'm wrong, but I am good at Lego's.

Really check that you are not horribly overfilled, yours didn't look too bad. Maybe try to replace just the sensor, looked like something comes out of the bottom of that thing(ET). Probably a good place to start from.

Last edited by Boondockz; 02-08-2014 at 03:25 AM.
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Old 02-08-2014, 12:14 PM   #27
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Quote:
Originally Posted by mjdehlin View Post
I've been experiencing a similar issue with an intermittent low coolant light. My ET is topped up to the correct level and I've been checking the coolant level almost daily and I see no loss of fluid.

The light comes on shortly after the temp gauge hits the 12 o'clock position (75 C) I've been using the gauge cluster computer to read the operating temps in menu 7.0 and it seems to be a little low (88-90C) when fully warmed up. The temps here have been extremely cold (-10 to -25 deg F ) ..could it be possible the the 2-5 degrees lower than the optimal 92-95C deg range is because of the extreme cold? I also noticed a bit of the yellow 'mayo' on the underside of my oil fill cap indicating some condensation build up.

Lately the heater seems take longer to warm up than usual even though the engine has warmed up to the 12 o'clock position. It's as if the valve that controls coolant flow to the heater core is not opening right away because I'll suddenly see the needle drop below 12 o'clock as cold coolant rushes into the system and then warm air will finally begin to blow from the vents. Any chance this delayed opening of the coolant valve to the heater core could be due to the extreme cold temps outside?

Would any of these symptoms point to a soft failing thermostat?

Once it warms up a little outside I plan to swap the coolant level sensor with the washer fluid sensor (since they are the same part) and see if there any difference in the behavior of the low coolant light.

In the spring I plan to fully replace the entire cooling system since I'm pushing over 130,000 miles on what I believe to be all original cooling system hardware. (Thanks to Mango for the excellent thread on the subject)
Seems to me that it could be a failed open thermostat, that 'mayo' however is not a good thing at all, and I would bet not related to the tstat. Water should not be in your oil...I would drain it immediately and see how much is in there...maybe its just from winter humidity/ sucking up rain. Haven't looked at my fill cap recently but my CAI gets wet a lot.

Check out that ccv system.

Last edited by Boondockz; 02-08-2014 at 01:44 PM.
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Old 02-09-2014, 01:13 AM   #28
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What I heard from a mechanic is that it could be the ratio of the coolant and the water in the system especially if it does that only during the winter time.

Try bleeding with perfect 50/50 ratio, and make sure expansion tank is full with coolant.




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Old 02-09-2014, 09:58 PM   #29
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Quote:
Originally Posted by Boondockz View Post
From the pictures I have seen, your ET is overfull, the top of that stick should be even with the rim of the ET when cold. That's from the owners M. once that bottom mark (overfull mark) is at the rim you can keep adding and the stick can't keep rising up.

It only says overfull once and in one way no mater how overfull it is. Check that immediately.

Two, majorly an air bubble is not going to cycle through your expansion tank trigger a low coolant light and go back into the engine. They are actually designed to trap any small bubbles that are in the system in the et, if there are little bubbles, you run the car till normal temp then let it cool completely and all of a sudden there's a lot less coolant in your ET because the air is there instead. Major bubbles can Block the tstat and cause an over heat tho. Not the issue here.

Third normal opreating temp is about 84 to 98 c. Your tstat, if it is a stock temp, is set for 97c. I have heard BMW says 70 - 115. That's really extreme tho 115 and I would be freaking out.

Look up the instrument cluster tests. Real time digital water temp as you drive. Keep an eye on that Reallly nice feature.

I would put my money on the sensor. That coolant level sensor i believe is a magnet on/in the stick maybe it fell out? Or its just bad. Or maybe I'm wrong, but I am good at Lego's.

Really check that you are not horribly overfilled, yours didn't look too bad. Maybe try to replace just the sensor, looked like something comes out of the bottom of that thing(ET). Probably a good place to start from.
Thanks for the information about the expansion tank, regarding air. The first photo I posted was of the expansion tank when the car was accidentally warm.

The second photo I let the car sit over night - I've been looking at the gauge 2 or 3 times a week, and that red gauge is always between the two spheres (which the expansion tank depicts as the proper height).

I'm going to print out the sequence of events so I can get the engine coolant temperatures sent to the OBC while i drive.
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Old 02-19-2014, 09:07 PM   #30
gman35
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Does anyone know where i can get disassembly procedures for replacing the ET on my 325ci bmw ? it is a 2006 model... I noticed a few drops of coolant under the car.. and now i have a little worse leak dripping under the car.. it drips around the middle of the car , paralel with the mirrors. I do notice there was a slight amount of fluid on top of the ET. car is a 2006 with 66K original mileage.. and temp gauge has never gone past the mid point or 12 oclock position. thanks, gary
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Old 02-21-2014, 12:51 AM   #31
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Quote:
Originally Posted by Sigrid7993 View Post
I'm pretty sure I purchased the level 2 cooling kit from ECS (link). I ended up noticing that the bottom corners of the radiator were leaking coolant, and ended up replacing the radiator with an OEM part bought across the BMW parts counter.


I like this idea; however in the process of swapping the sensors - am I going to introduce air into the cooling system (or just lose coolant)?


I'm referring to the bleeder screw (part #2 link). The coolant only leaks when I purposely loosen the screw.

Yesterday evening the low coolant light came on twice during my commute (car was warmed up; about 20 miles - mostly highway driving) so I left the engine running, turned the heat to 90f, popped the hood and loosened the bleeder screw. I had a rag over the hose because I wasn't sure how pressurized the system would be if I over-loosened the screw. I was slow to loosen the screw; I didn't hear any obvious air hissing - and then I eventually got to a point where the rag quickly became wet with coolant so I closed the bleeder valve.

And I noticed the problem on my commute in this morning.
hmm before I replaced the radiator I was having this issue and I WAS leaking coolant. Sometimes it would come on other times the light would go off.

I replaced the radiator, expansion tank, and expansion tank thermostat. I also replaced the upper hose. It could have been only the radiator but I replaced the others just as routine maintenance. Problem did not come back.
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Old 02-21-2014, 12:54 AM   #32
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Originally Posted by gman35 View Post
Does anyone know where i can get disassembly procedures for replacing the ET on my 325ci bmw ? it is a 2006 model... I noticed a few drops of coolant under the car.. and now i have a little worse leak dripping under the car.. it drips around the middle of the car , paralel with the mirrors. I do notice there was a slight amount of fluid on top of the ET. car is a 2006 with 66K original mileage.. and temp gauge has never gone past the mid point or 12 oclock position. thanks, gary
Took me 10 second to search "expansion tank replace e46" on youtube, and here is the first result, a good video tutorial:


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Old 02-21-2014, 12:54 AM   #33
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Old 03-04-2014, 08:26 PM   #34
Dluxx88
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Im having the same problem. I even went as far as to pressure test the system, with no leaks or lost pressure. if it is just a sensor, why would it only 'malfunction' in the cold months? That makes no sense. has anyone had problems with heater cores leaking?

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Old 03-10-2014, 06:02 PM   #35
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It seems no one has an answer to this yet? Im still having this issue, how ever I replaced all of the crank vent hoses and oil separator and it has been coming on alot less. I would assume just a coincidence though. I have been tracking this with relation to engine temps and it seems to have a trend of coming on right before the thermostat opens up. My temp will rise to about 210-212F (with the light on) then the light will go off and about simultaneously, the temp will shoot down to about 180F as if the T-stat just opened up letting a flush of cool coolant in. Im thinking it could be a combination of the T-stat and level sensor. My T-stat is aftermarket, not sure if it could be some weird issue?
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Old 03-10-2014, 07:25 PM   #36
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E46 emailed me when MonkeyMouse asked for an update.. I don't have a whole lot to report, but here is a recap:

Since starting this thread my bmw's coolant level has not changed, I've driven a total of 1400 miles, over roughly 3 months.

In the morning (prior to starting the car, car has been in 40f garage for 10+ hours), the coolant dipstick still reads like this:


I went thru my receipts; and found the exact items I used when updating my 2001 330i (manual trans) cooling system:
* ECS Cooling System Level 2 Refresh kit (link)
* Behr Bmw Radiator from EEuroParts (link)

I don't believe that the ECS kit was comprised of actual 'Genuine BMW' parts; however everything appeared high quality, flipping thru photos found on the ECS site, I'm seeing 'Made in Germany' stamped on most of the parts. Again, these parts were all installed in August of 2012, meaning they are roughly 18 months old, with somewhere between 10 and 15,000 miles.

In my experience, A failing or failed engine thermostat is easily diagnosable in the Winter months by the lack of heat inside the cabin (this is because thermostats fail open, recirculating coolant throughout the engine, instead of closing - thus diverting hot coolant to the heatercore).

In my case the cabin HVAC/Heater unit works well, heating the cabin quickly after leaving a heated garage. Returning from work there have been days where the car was parked in -5f weather. On those days it would take 10 minutes or so until the cabin was getting any meaningful heat.

In all cases the thermostat gauge found on the dashboard always get's to the 12 o'clock position before the cabin heater is able to provide full heat. I've never seen the thermostat gauge change in either direction once it has reached the 12 o'clock position.
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Old 03-10-2014, 11:53 PM   #37
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1400 miles in 3 months. Man I'm envious I do at least 6000 in 3 months. Ive had this light on and off for about 10k now with no real issue.

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Old 03-10-2014, 11:57 PM   #38
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Also you won't see the temp gauge on the dash change much as it has a built-in buffer to keep it dead center at a given temp range. You need to either use a plug in gauge or the hidden cluster stuff to accurately judge temperatures.

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Old 03-17-2014, 05:13 PM   #39
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I think I may have air in the system? Could that cause the light to come on some times? Along with overheating at idle? I'll have to try bleeding it again soon I guess.
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Old 03-19-2014, 07:32 AM   #40
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I had a similar issue this winter. I first bled the system, that wasn't the solution. I then replaced the coolant level sensor at the bottom of the tank. That wasn't the solution. I had some further checking done and a small leak was found in the upper radiator hose as well as the float in the ET was the issue. Both replaced, problem solved.

This winter we've had a lot of sub 0 temps, and according to BMW the float stick level is to be read at 68F. Turns out the PO had overfilled the coolant system and I had done so as well since I was checking coolant levels at 10 to -5 ambient air temp and not 68.

I also had the mayo issue on the inside of the oil cap and was alarmed as I was having a cooling issue. I did an oil change and found the oil was water free. I cleaned out the "mayo" and after doing some research and monitoring of my oil cap for the last 3 weeks I've found it's possible to get condensation in very cold temps. Since my commute is only 10 minutes I apparently wasn't driving enough to "boil off" the condensation. I've been mayo free since temps have risen and I take it for an extended 20 minute ride once a week.
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