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another heating problem

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Hey guys. So ive searchesd alot for heating problems and ffind em everywhere. But none that are doing exactly what mine is. So my heater works great, when im moving but when i sit at a light it blows cold air or if i maintain the same sleed for a while itll bblow cold too. I'm thinking iits the microfilterr but woundering what else it might be.
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Your thermostat may be stuck in the open position or you could have a problem with the heater valve.

Steve
Thermostat I hope is ggood cause i replaced it right b4 I bought the car. .. I did put in genaric coolant cause it was b4 i knew i needed a certain kind. Do u think tthat would effect it?
No. If the t-stat is relatively new, then I would suggest you start investigating the heater valve.

Steve
Crap that's probably not a cheap easy fix huh? Any suggestions to be able to see if its that without reaplacing it
I've never done one myself. I don't think it is technically difficult to do, but I'm not sure on the cost of the heater valve, but likely not inexpensive.

I would recommend that you wait for others to chime on with their thoughts. I may not be on the right track and certainly wouldn't want you to replace a heater valve on just my thoughts.

The guys will likely chime in later. I would suggest you Google "E36 heater valve replacement". You should get a lot of useful information.

Steve
Awesome thanks man. This place has been pretty good at helping me out and im sure i can find a diy on google. So ill wait for other replys and do some research. Hope I can figure it out soon. I'm sick of "warming up" the car for 20 min and it still being cold lol
I forgot to ask. During the fluctuations in cabin temperature, what is your water temp gauge showing?

Steve
Awesome thanks man. This place has been pretty good at helping me out and im sure i can find a diy on google. So ill wait for other replys and do some research. Hope I can figure it out soon. I'm sick of "warming up" the car for 20 min and it still being cold lol
90% to the time it's dead center the others it's a little over middle so its saying its at a good running temp. Doesn't go to overheating level or anything though
Yeah. I think that rules the t-stat out. I think that likely points to the heater valve.

Steve
90% to the time it's dead center the others it's a little over middle so its saying its at a good running temp. Doesn't go to overheating level or anything though
That was my thoughts too for ruling that out cause before I changed it it would do the thing where it would say it is "overheating" but not be affecting the car.
Your temp gauge should NEVER go past 12 o'clock position. Try bleeding your system again, (3 or 4 times) then try it a few more days. My money from that description is that you've got air in the system.
It is not uncommon for the gauge to read 2-3mm above the 12 o'clock position. Now, if he is referring to it going up more than that (such as near the 3/4 mark), then I agree that he may need to bleed it again.

Steve
Your temp gauge should NEVER go past 12 o'clock position. Try bleeding your system again, (3 or 4 times) then try it a few more days. My money from that description is that you've got air in the system.
Yeah it bairly passes the 12 but I will try bleeding again anyway. With bleeding lifting up the front end makes it better right? Or was that for something else? And is the genaric 50/50 blends ok for coolant or should i do a flush and put in bmw specific?
In my experience the only reason for it to ever be above the TDC position at all is that it is common for people to not have bled the system properly and it has air in it.
Mine E36 has run 2-3mm past straight up ever since I overhauled the cooling system some 50K miles ago. Again, this is not uncommon. I have seen it over on the E34 forum as well. Anything more than that though and I would be investigating it.

Steve
In my experience the only reason for it to ever be above the TDC position at all is that it is common for people to not have bled the system properly and it has air in it.
So sense its the easiest and cheapest ill do the bleed today. If thats not it should I look straight towards the heater valve? Or is the a chance that the are other areas such as the cabin filter or something? Also would to much coolant make it do this? Cause when i bleed it then have it run to operating temp the coolant level drops a little but is always well above the "full" line on the tank
Temperature fluctuation has nothing to do with the cabin microfilter, so you can rule that out. And I would only use BMW blue coolant.

Also, if your cooling system is functioning as it should, the temp needle should never move beyond 12 o'clock - not even by 1mm. Ever.
K cool. So if its nnot the bleeding ill do a flush (ill do one anyway eventually) and if that still doesn't help ill check the heater vaulve. And just work my way from there... Water pump wouldn't be an issue would it? If so do they have a "weeping" eye? At least thats what I've heard em been called for other cars.... The little hole that leaks if the pump is bad.... I'm assuming considering its blowing hot air sometimes the heater core wont be bad... Or is that the same as the valve? Sorry for all the questions. I'm still pretty new to the engine on bmws.
Oh is the bmw blue coolant called "bmw blue coolant" or does it have a dif name?
No, it doesn't have another name other than BMW coolant.

For now, just focus on bleeding it correctly and ensuring that it is at the correct level. Since you replaced the t-stat before you purchased the car, I'm fairly certainly you did not successfully get all the air out of the system. This would cause the exact symptoms you are describing, and many people cannot get it right on the first try. You most likely have trapped air in the system.

It's most likely not your water pump, and there is no weeping eye on the E36. And contrary to what was said above, the temp needle should never go beyond 12 o'clock. Just bleed your system using the correct procedure and report back afterward.
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