Plugged heater core. BMW F32 435i

BMWTurboDzl

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My vehicle developed a no heat condition and I think I've narrowed it down to a plugged heater core. There's a heater control valve on the inlet hose which controls the amount of heated coolant making its way to the heater core. My diagnosis is based upon the fact that the inlet hose between the control valve and the heater core is warm which leads me to believe that the control valve is functioning. The outlet hose is cold.

I'm wondering what sort of experience people have flushing the core only OR whether you guys think it's easier to just use a cleaner flush on the entire system?

Recommended products? Liqui Moly, Motul, and others have a 500 ml "pour-n-idle" product.

My engine (N55) has an electric water pump and I don't have a block drain so I don't know how I would flush out any cleaner.

UPDATE: 63k miles on the odo. 2015 MY
 
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BMWTurboDzl

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How do you know the valve to the heater core is open? How do you know the door that directs air over the heater core is properly actuated? And finally, is there enough coolant in the system. A small amount of missing coolant will leave an air bubble that can, on some cars end up in the heater core. It will act as very poor heat levels. It happened on my Pontiac Vibe last month. No one on this site believed me but adding 4 ounces of coolant and burping the system fixed the issue. I doubt you have a clogged heater core.....remember the heater core itself does not hold much fluid so a 4 ounces of air is significant.
As I said in my OP the hose between the valve and the core is warm. The output hose was ice cold.

I spoke with another technician and he said that input hose should be hot not warm. So I should compare the temp of each section before/after the HCV. Hot hose before / warm hose after = probable failing HCV. If both hoses warm could be aux heater water pump if I have one i don't think I do.

The hoses and HCV are easily accessible due to the I6 layout. See post #27 showing the part.

Coolant level is fine.

I could also be the blend door or broken wire or SW issue but I really have no idea w/out a code reader.
 
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As I said in my OP the hose between the valve and the core is warm. The output hose was ice cold.

I spoke with another technician and he said that input hose should be hot not warm. So I should compare the temp of each section before/after the HCV. Hot hose before / warm hose after = probable failing HCV. If both hoses warm could be aux heater water pump if I have one i don't think I do.

The hoses and HCV are easily accessible due to the I6 layout. See post #27 showing the part.

Coolant level is fine.

I could also be the blend door or broken wire or SW issue but I really have no idea w/out a code reader.
Hot input and cold output would indicate you have flow and the heater core is taking the heat. No flow and the input line should maybe be only luke warm.
 

OVERKILL

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As I said in my OP the hose between the valve and the core is warm. The output hose was ice cold.

I spoke with another technician and he said that input hose should be hot not warm. So I should compare the temp of each section before/after the HCV. Hot hose before / warm hose after = probable failing HCV. If both hoses warm could be aux heater water pump if I have one i don't think I do.

The hoses and HCV are easily accessible due to the I6 layout. See post #27 showing the part.

Coolant level is fine.

I could also be the blend door or broken wire or SW issue but I really have no idea w/out a code reader.
The technician is correct, the hose going into the core should be HOT, the same temp basically as your other hoses, if it is only warm, there's no flow going on there and the heat is just coming from convection. There will be some loss through the core (the exit hose will be warm vs the hot of the inlet hose) but it sounds to me like it's the valve, as he and you are now both suspecting.
 
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Quick Q. Assuming you have protool, are codes in english or german? I watched a video which suggested german but I wasn't sure if that was due to a user setting.
I actually don’t. But will install soon as I need to tune DME for 3 stage intake.
Did you check Bimmergeeks web site? I think they have all correct versions of INPA and ISTA.
 
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How do you know the valve to the heater core is open? How do you know the door that directs air over the heater core is properly actuated? And finally, is there enough coolant in the system. A small amount of missing coolant will leave an air bubble that can, on some cars end up in the heater core. It will act as very poor heat levels. It happened on my Pontiac Vibe last month. No one on this site believed me but adding 4 ounces of coolant and burping the system fixed the issue. I doubt you have a clogged heater core.....remember the heater core itself does not hold much fluid so a 4 ounces of air is significant.
The heater core AND the AC evap both get all airflow. The heater core is under the AC evap. Why? The evap has a temperature sensor which is used to detect when the evap is nearing the freezing point. At that point the automatic climate control module (IHKA in BMWspeak) opens the heater control valve enough to warm the air going up and through the evap, thus preventing evap freeze up.

OP, I'm betting the heater control valve is the culprit. The valve is open unless the IHKA supplies electrical power (constant or pulsating 12VDC, depending on the the cabin and exterior temperatures). What's happening, IMHO, is the valve is partially blocked. I recommend that you have the coolant replaced once this issue is resolved. I do not buy into BMW's 5 year coolant protocol. I had my coolant changed at 4 years and 22k miles. ALWAYS use BMW coolant and DISTILLED water!
 

BMWTurboDzl

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UPDATE:

Downloaded Bimmergeeks Protools (Androi APP). It seems to be a piggyback on top of BMW INPA (factory diagnostic) rather than ISTA+ (Dealer diagnostic) which is a bit of a bummer. The APP is pretty slick and easy to navigate. Unfortunately if you, such as myself, don't have/refuse to use Facebook the user forum is out of reach.

So last weekend before a long trip I quickly performed the following:

No engine related codes so I guess I can assume my thermostat is working fine.
Located some A/C capacity codes and reduced power codes (ex, rear window defroster) which I think, respectively, relate to when my refrigerant had been a little low in 2021 and the current state of my battery. Cleared them and the A/C compressor codes have not returned.
I reset IHKA (BMW climate control system)
Tested and recalibrated flaps within the climate control system. - No codes


During trip back on Sunday night I had system set to "AUTO" , temp at 78 degrees w/AC off and the cabin did not get over 70-72 degrees.

Today I'm going to try to figure out how to locate and monitor the position of the blend doors at max temp. Hopefully I'll be able to narrow it down to the blend doors.

If I can rule out the blend doors then I may throw a new heater control valve at the car. However a couple of months ago I felt the output hose from the heater core after a long drive and it seemed hot rather than warm so for the moment I'm ruling it. From what I understand the default position is "open" so a failed valve would result in too much heat rather than too little although perhaps it has failed in the half-open position and can't open further. I can't imagine how that would happen.

My APP doesn't seem to be able to test this functionality.
 
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Does your engine temp ever reach normal temp? If so, how quickly? How's your fuel economy?

I think I would try ruling out T-stat first, as it's cheaper and probably easier to get to and replace. It could just be stuck open.
 

BMWTurboDzl

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Does your engine temp ever reach normal temp? If so, how quickly? How's your fuel economy?

I think I would try ruling out T-stat first, as it's cheaper and probably easier to get to and replace. It could just be stuck open.
I haven't measured FE but on highway trips it appears to be inline with expectations. I only have an oil temp gauge and it starts coming off the bottom within 2-5 miles which has always been normal. What hasn't been normal is that it seems to take longer to reach just shy of dead center. The cooling system has two maps. One for fuel efficiency (hotter) and the other for performance (cooler). On drive home this past Sunday I noticed the needle would occasionally drift a few degrees cooler than normal but I may be hypersensitive and we're only talking 2-3 indicators off normal anyways. No codes for thermostat unfortunately. I've ready where some owners are getting an intermittent issue and it's not throwing a code.

The vehicle really needs to be on a lift with the belly pan removed to replace it. I don't have a lift nor do I have a suitable catch basin for the coolant.
 
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