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General E46 Forum
This is the place to get answers, opinions and everything you need related to your E46 (sedan, coupe, convertible and wagon) BMW!

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Old 06-24-2011, 09:21 PM   #41
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Join Date: Apr 2008
Location: Dallas, TX
Posts: 2,217
My Ride: E30-E46-E90-E90M-F30
I am not sure if already solved this problem but this is what I did when I ENCOUNTERED THE SAME EXACT PROBLEM.

I put the car on nuetral and then REV my engine to like 4-5K constant for 30 seconds for a few times. I don't know what I did but that solved my problem when re-bleeding didn't help, when replacing the heat valve didn't work, and eveyrthign else i could think of.

BTW...I did this with the FAN on MAX and temperature on MAX hot.

Last edited by flashmeow; 06-24-2011 at 09:23 PM.
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Old 06-25-2011, 07:43 PM   #42
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Join Date: Sep 2010
Location: Melbourne, Australia
Posts: 693
My Ride: 2007 335i Coupe
No that doesn't work.
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Old 10-27-2011, 09:31 PM   #43
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Join Date: Dec 2010
Location: Lexington
Posts: 254
My Ride: 1999 328i
Bumpity bump,
I have a similar issue. When I first got my car, I changed the thermostat and bled it out and had no problems with heat or the cooling system. Today was the first cold day in a while so when I started the car, I turned the heat on and rolled out of the driveway. Traffic starts at my driveway so it took like 10 minutes to get through the first light. The whole time I had no heat and the temp gauge was dead middle. After I got through the first light and up to speed, I magically had heat and sitting at stop lights I had heat. I just considered it a fluke because on the way home I had heat with no issues. After some troubleshooting, here is what I have, see what you think,

On a cold start, I have no heat no matter how long I let it idle or how much I rev it. Once I start driving, the heat works as well as I could ask for, even at stop lights and parking lots idling. The temp gauge never moves from halfway.

When I got home tonight I did some poking around and this is what I found: The upper radiator hose is hot, the lower radiator hose is not. At the water valve, both hoses are hot but halfway down one of them, towards the heater core it is cold while the other one is super hot.

So my suspects are the Thermostat because the lower radiator hose is not hot at all, even after a drive to Walmart and back, this is the same thermostat that I put on less than 10,000 miles ago. My other suspect is the water valve because I would think that both hoses should be hot with the heat on and it is an electrical part on a BMW. I've read a bunch of threads where people have changed it to no avail though. My last suspect is the water pump but I'd think the car temp would start moving to the red if it was failing or even intermittent.

no heat on a cold start no matter how long it idles
great heat when I start driving and never reduces in temp even while idling or parked.
no heat problems on warm starts
No coolant issues at all, level is good and never had a problem last winter.
suspect water pump, recently installed thermostat or water valve.

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Old 12-18-2014, 08:59 AM   #44
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Join Date: Jun 2002
Location: Indy
Posts: 179
My Ride: Z4M-R, 330i
old thread but....

I had the heat go whacky recently in my 2002 e46 330i.
I had COLD air in the face and side vents while I got heat at the windshield and floor. !!
I had no idea what this could be from.

then it occurred to me I recently has the radiator flushed at my indy garage...

I took it to my BMW master tech at the dealer thinking I might have a bad water valve. At least I needed a thorough diagnostic.
Nope not a broken part! It has a bubble in the heater core.
They vacuum bled the cooling system (properly), refilled, >>> fixed!!
nice and toasty now just in time for the cold front in Indiana.

Got a refund from the indy garage for the radiator flush!
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Old 12-18-2014, 09:26 AM   #45
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Location: Newburyport Ma,
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As I've said before always always look at what the last idiot did to the car. Even if the idiot is you! We all make mistakes.
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Old 01-16-2017, 03:40 PM   #46
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Join Date: Dec 2016
Location: Canada
Posts: 4
My Ride: BMW E46
i just got my 330ci last month i dont really have experience under the hood, the heat comes out from the feet side and the front windshield fog remover side, but from the front ones facing me its cold air?!? its really weird cuz it makes heat but fails to direct it to my me, iv tried all the settings, i have read this thread, i also put in about 3/4 of a liter of antifreeze so its full so its not that, it was working fine on Christmas tho, also its very cold outside if that has anything to do with it (Canada GTA) Any idea of the cause? Thanks!
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coolant, heater, temperature, valve

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