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      01-21-2022, 07:00 PM   #1
F82 in QC
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Heater is blowing cold air when idle(car fully warmed)

Hi guys,its pretty cold here these days(-20 celsius) ,the problem is that even with fully warmed car it blows out cold air at idle,when driving its working normally,if i keep engine rev above 1k at idle it will blow warm air.
Someone had this problem before?
It should overheat the engine if the problem is waterpump since its electric so im thinking maybe its a clogged heater core?
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      01-21-2022, 09:19 PM   #2
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Heya,

Is it possible there is a thermostat that is closing in an effort to keep the engine warm? Being from the north it make sense if there is such a thermostat.

When I lived in Truckee, Ca. some of my older vehicles thermostat would not open for a LONG time when the temps dipped below zero. Therefore, the heater core didnt get warm for a while. But it was only when it was very super cold.

I know that is probably too simple of a solution for these cars, but possibly it is similar?

Someone who knows more about htese motors than I do will chime in soon...

Interested myself to see whats going on....

good luck!
josh

Last edited by spidy512; 01-21-2022 at 09:28 PM..
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      01-25-2022, 09:09 PM   #3
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Quote:
Originally Posted by spidy512 View Post
Heya,

Is it possible there is a thermostat that is closing in an effort to keep the engine warm? Being from the north it make sense if there is such a thermostat.

When I lived in Truckee, Ca. some of my older vehicles thermostat would not open for a LONG time when the temps dipped below zero. Therefore, the heater core didnt get warm for a while. But it was only when it was very super cold.

good luck!
josh

Majority of vehicles if not all, have heat exchanger (cabin radiator) in closed loop with the "hot side" of engine coolant or before thermostat. That way cabin heat is always available as long as coolant around cylinders is hot.
Some older vehicles are just poorly designed, usually with one coolant pump for the whole system, long coolant hoses with small diameter to the heater core with bunch of heat loss everywhere in seriously cold conditions. More often it's an old diesel engine which cools itself idling hence high idle invention for them.

When engine struggles getting to operating temperature it means thermostat is stuck open (fully or slightly or simply coolant flow pushes it open) and coolant flows trough radiator up front cooling it down further instead of just circulating trough the engine itself and heat exchanger. On cold engine thermostat is always closed and while it warms up, it opens to bring cooled coolant from the radiator and maintain safe operating temperature.

On older vehicles thermostat is often mechanical which gets weak after few years and should be replaced more often. Bmw has had ECU controlled thermostat for a long time now. It makes engine run hot (example 105-110C) while driving slow for better efficiency or if driving high speeds or high revs for a while it lowers the engine temperature down (example 78-90C). This would be opposite with mechanical thermostat.

BTW that efficiency thing of running hot is what's been killing plastic cooling components and baking rubber gaskets into the plastic on Bmw's since late 80's. If it never run above 90C everything would last much longer.

Quote:
Originally Posted by F82 in QC View Post
Hi guys,its pretty cold here these days(-20 celsius) ,the problem is that even with fully warmed car it blows out cold air at idle,when driving its working normally,if i keep engine rev above 1k at idle it will blow warm air.
Someone had this problem before?
It should overheat the engine if the problem is waterpump since its electric so im thinking maybe its a clogged heater core?
Engine coolant pump is belt driven, there is electric one for heat exchanger. I'd suspect that one is dead or weak and with rpms raised belt driven pump pushes more coolant and heat comes in.

Electric one is helpful when the engine is off and cabin heat is needed, it'll blow warm until coolant gets cold. That's a way to test it if it works and if you can find it underneath the hood. Should be on the drivers side of the engine, behind/bellow coolant expansion tank, closer to the cabin. Number 9 in the picture.

I drove mine in -36C and haven't experience lack of cabin heat while idling even for longer periods.
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      01-31-2022, 09:10 PM   #4
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I'm having this exact issue as well on my 2017 f80 with 58k miles. Was just searching the forum hoping to find some answers.
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      01-31-2022, 09:42 PM   #5
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Quote:
Originally Posted by F82///M View Post
Majority of vehicles if not all, have heat exchanger (cabin radiator) in closed loop with the "hot side" of engine coolant or before thermostat. That way cabin heat is always available as long as coolant around cylinders is hot.
Some older vehicles are just poorly designed, usually with one coolant pump for the whole system, long coolant hoses with small diameter to the heater core with bunch of heat loss everywhere in seriously cold conditions. More often it's an old diesel engine which cools itself idling hence high idle invention for them.

When engine struggles getting to operating temperature it means thermostat is stuck open (fully or slightly or simply coolant flow pushes it open) and coolant flows trough radiator up front cooling it down further instead of just circulating trough the engine itself and heat exchanger. On cold engine thermostat is always closed and while it warms up, it opens to bring cooled coolant from the radiator and maintain safe operating temperature.

On older vehicles thermostat is often mechanical which gets weak after few years and should be replaced more often. Bmw has had ECU controlled thermostat for a long time now. It makes engine run hot (example 105-110C) while driving slow for better efficiency or if driving high speeds or high revs for a while it lowers the engine temperature down (example 78-90C). This would be opposite with mechanical thermostat.

BTW that efficiency thing of running hot is what's been killing plastic cooling components and baking rubber gaskets into the plastic on Bmw's since late 80's. If it never run above 90C everything would last much longer.



Engine coolant pump is belt driven, there is electric one for heat exchanger. I'd suspect that one is dead or weak and with rpms raised belt driven pump pushes more coolant and heat comes in.

Electric one is helpful when the engine is off and cabin heat is needed, it'll blow warm until coolant gets cold. That's a way to test it if it works and if you can find it underneath the hood. Should be on the drivers side of the engine, behind/bellow coolant expansion tank, closer to the cabin. Number 9 in the picture.

I drove mine in -36C and haven't experience lack of cabin heat while idling even for longer periods.
im also having squeky belt issue at cold start maybe they are related,gonna find out at dealer soon
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      02-01-2022, 07:28 PM   #6
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Quote:
Originally Posted by F82///M View Post
Quote:
Originally Posted by spidy512 View Post
Heya,

Is it possible there is a thermostat that is closing in an effort to keep the engine warm? Being from the north it make sense if there is such a thermostat.

When I lived in Truckee, Ca. some of my older vehicles thermostat would not open for a LONG time when the temps dipped below zero. Therefore, the heater core didnt get warm for a while. But it was only when it was very super cold.

good luck!
josh

Majority of vehicles if not all, have heat exchanger (cabin radiator) in closed loop with the "hot side" of engine coolant or before thermostat. That way cabin heat is always available as long as coolant around cylinders is hot.
Some older vehicles are just poorly designed, usually with one coolant pump for the whole system, long coolant hoses with small diameter to the heater core with bunch of heat loss everywhere in seriously cold conditions. More often it's an old diesel engine which cools itself idling hence high idle invention for them.

When engine struggles getting to operating temperature it means thermostat is stuck open (fully or slightly or simply coolant flow pushes it open) and coolant flows trough radiator up front cooling it down further instead of just circulating trough the engine itself and heat exchanger. On cold engine thermostat is always closed and while it warms up, it opens to bring cooled coolant from the radiator and maintain safe operating temperature.

On older vehicles thermostat is often mechanical which gets weak after few years and should be replaced more often. Bmw has had ECU controlled thermostat for a long time now. It makes engine run hot (example 105-110C) while driving slow for better efficiency or if driving high speeds or high revs for a while it lowers the engine temperature down (example 78-90C). This would be opposite with mechanical thermostat.

BTW that efficiency thing of running hot is what's been killing plastic cooling components and baking rubber gaskets into the plastic on Bmw's since late 80's. If it never run above 90C everything would last much longer.

Quote:
Originally Posted by F82 in QC View Post
Hi guys,its pretty cold here these days(-20 celsius) ,the problem is that even with fully warmed car it blows out cold air at idle,when driving its working normally,if i keep engine rev above 1k at idle it will blow warm air.
Someone had this problem before?
It should overheat the engine if the problem is waterpump since its electric so im thinking maybe its a clogged heater core?
Engine coolant pump is belt driven, there is electric one for heat exchanger. I'd suspect that one is dead or weak and with rpms raised belt driven pump pushes more coolant and heat comes in.

Electric one is helpful when the engine is off and cabin heat is needed, it'll blow warm until coolant gets cold. That's a way to test it if it works and if you can find it underneath the hood. Should be on the drivers side of the engine, behind/bellow coolant expansion tank, closer to the cabin. Number 9 in the picture.

I drove mine in -36C and haven't experience lack of cabin heat while idling even for longer periods.

Where did you find this break down? I looked on real oem and didn't see it. Looking to find oem part number to see if dealer has it available. Bosch pump is on back order and probably wouldn't see it until at least a month from now.
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      02-01-2022, 08:26 PM   #7
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Have you checked the mixing valve on the front middle vent? If it's set to blue (cold) you won't get warm air.
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      02-01-2022, 09:57 PM   #8
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Quote:
Originally Posted by MrSmartyPants View Post
Have you checked the mixing valve on the front middle vent? If it's set to blue (cold) you won't get warm air.
its all the way to red,i always use this nob instead of ajusting the temperature
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      02-09-2022, 04:23 PM   #9
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Bump in case anyone has any more info on this or has experienced this as well.
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      03-25-2023, 09:18 AM   #10
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Hi Guys, I've now got the same problem on a 2015 f83. Heater works fine at medium to high rpm, as soon as I idle the heater goes cold. Can you guys advise what worked for you in terms of fixing this. Was it the thermostat or the electric water pump or something else.
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      03-27-2023, 08:28 PM   #11
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Quote:
Originally Posted by GazM4 View Post
Hi Guys, I've now got the same problem on a 2015 f83. Heater works fine at medium to high rpm, as soon as I idle the heater goes cold. Can you guys advise what worked for you in terms of fixing this. Was it the thermostat or the electric water pump or something else.
was electric water pump for mine
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