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strange coolant issue, please help

2K views 18 replies 11 participants last post by  tcphoto 
#1 · (Edited)
A week ago I did a coolant flush, and put in a new 50/50 mix of BMW coolant and distilled water. I drained from both blue drain plugs up front, as well as the plug on the engine block. When I refilled, I bled it to the best of my ability, with the bleeder valve open, I filled it till it got full and dribbled out, then the level would subside as air excaped, and I repeated this process a few times until the level no longer dropped. Tightened the bleeder screw, and everything was good. Made a few trips, totalling maybe 100 miles. Everything was gravy, my temp gauge was where it should be I had hot heat, all good. But then a few days ago my low coolant light came on, so I topped it off, and took another short trip. On this trip I noticed my heat was not warm at all, and after 10-15 minutes, low coolant light came on again. So I took it back home, topped it off again. It never was more than a few ounces low each time. While all of this was going on, my temp gauge never went past the halfway mark. So last night I went for another short drive. The temp gauge was in the middle, low coolant light never came on, but my heat was still not warm. So I went home. When I pulled into my neighborhood, temp gauge was still in the middle. In the time it took me to turn around and back into the garage, the temp gauge went into the red, but there was no low coolant light or any warning lights of any kind. I immediately shut the car off. It was late so I didnt pop the hood, but I felt the hood and it was ice cold, so idk if this was a false reading or what?? Upon further inspection the next day, I did notice that there was a little coolant that appeared to have over flown and there was residue on top of the radiator, but not a large amount. Keep in mind, on the last trip, when the temp gauge went into the red, the low coolant light never came on. Where would the coolant be overflowing from? The radiator cap? I am assuming that somehow there is still air trapped inside and the water pump is not moving the coolant through the system, and thats why my heat isnt working?? But that makes no sense, I am pretty sure I bled the system completely. Also, if the system wasnt bled properly, why would I get 100 trouble free miles with warm heat before any issues arose?? Does anyone have any ideas? did I not bleed the system right? Please help.... :ben:

The car is an 01 330ci, 106k miles, all stock
 
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#2 · (Edited)
Dude, it's like you wrote out in a really long and detailed way of my experience dealing with the amazing cooling system.

inb4overhaulentirecoolingsystem

Look for leaks.


edit/
Bleeding the system to the best of your abilities should include in this order as far as I recall...

Keep car off
Put 50/50 mix in
Turn HEAT to 91 MIN SETTING ONLY
Wait for fluid to come out of bleeder
Start car
Coolant temp to 30*c
top off done
 
#4 · (Edited)
You do realize that you can not rely on the gauge to give you accurate temp readings. You have to go into the OBD to get the true temp. I woul bet you have been running at much higher than normal temps the entire time.
The coolant gauge is buffered, so that it does not show the normal swings in temps that your engine experiences. The temp can be as much as 30* Celsius higher than normal, and your gauge will still read dead center. You really need to monitor the actual temp in the OBD after any cooling work.

Read this thread for a more thorough explanation:
http://forum.E46Fanatics.com/showthread.php?t=964491
 
#10 ·
I missed the part after tightening the bleeder screw where you pumped out the excess coolant from the expansion tank in order to have the coolant at the correct level, i.e. with space in the expansion tank to, you know, expand.

Repeat and do this step, and then see what happens.

If it's still overheating after doing a proper bleed, then it's time to refresh the whole thing.
 
#14 ·
cool thanks guys, ill try to bleed it again. im pretty sure that has got to be my problem. everything was completely fine before flushing the coolant, so it just has to be air pockets right? but if it wasnt bled correctly, would that cause the system to overflow? i would think if anything, there wouldnt be enough coolant rather than too much. the coolant was at the proper level after my first attempt at bleeding, and I didnt have any issues for a few days, thats the only reason im a little unsure. also, if there arent any visible leaks, is it probable that the coolant is just coming out of the top of the expansion tank? the cap on there does not appear to be of the "pressure releasing" type. I havent had a chance to really look at it, been working long hours but i will take a look this weekend. I just need someone to reassure me that it was just a bleeding issue and nothing more serious. thanks again for all the info.
 
#15 ·
I had a car that I could not get heat when it was idling. It finally came to a head and my low coolant light would come on. Filled it up and 10 minutes later it was low on coolant. Car ran fine too. I could not find a leak and because it lost fluid so quick, I suspected a bad head gasket. Checked compression and found 2 cylinder lower.
Changed out my head gasket and she is running great and I have heat. Just relating my experience for some where this could be the case for them. I bought the car not running hoping to put a motor in it, but got it running because of a bad fuse and 9000 miles later I finally had to do the HG.
 
#16 ·
So I rebled the system today. Poured distilled water in until it ran out of the bleeder valve for about 2 minutes. I failed to do that the last time. Anyways, bled it out for 2 minutes, siphoned out excess coolant, and then took the car for a nice midnight drive through the hills. I was monitoring the temp through the OBC and it topped out at 96/97 C, it would bounce between the back and forth. From what I have read, thats exactly where it should be. Also, heat worked great. No coolant light. It appears that I have fixed the problem, and the car was running great, pulling like a freight train tonight with the dense cool midnight air. Thanks for all the help. I LOVE MY BMW!
 
#17 ·
TL;dr it all...but if you added a lot of distilled, you've affected your ratio, which should be around 50/50 plus or minus a little...not a lot.

Although you're probably entering warmer weather, you may be hit with some cold temps...keep car garaged if you added more than a few cups of distilled...or read the coolant bottle to get a sense of what temp you're now safe to...and fix things up for the next winter. Don't forget.

HTH
 
#18 ·
yea im sure the distilled water threw off my ratio a little bit. I am going to use one of those coolant testers that tell you what temperature youre coolant is good to, hopefully its not too far off. I didnt want to spill antifreeze all over my engine, thats why i used water. and i do park in the garage, i should be ok.
 
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