[juegomaestro]

Vehicle: 2013 BMW 335i Xdrive F30 - 120k miles
Problem: Significantly less heat coming from driver side vents compared to the passenger side.
Dealer's take: Clogged heater core. Replace heater core.

Instead of replacing the heater core, I flushed the heater core independently from the rest of the system. I flushed it forward and reverse, many times. I also poured white vinegar inside the core and let it stand for an hour before flushing it out with distilled water. It took a while as each time I changed flow direction, more chunks of what looked like gold dust or sand kept coming out. Once I started not getting anything more, I reconnected everything and purged the system. My heat returned to full blazing heat (maybe hotter than when I bought it) which is great but slowly over maybe a month, the vehicle returned to the original problem.

I get the feeling that maybe corrosion is coming from other parts of the system (i.e. radiator) and maybe I should replace that, or maybe the heater core is just re-corroding itself again.

I am thinking of trying to use Irontite ThoroFlush on either the heater core alone or the whole system. Has anyone tried using this before? Was it effective? Is it safe? Could it harm the waterpump?

I don't feel like my radiator is bad. I don't have any overheating issues. If anything, it seems to take longer than usual for the oil temp gauge to get to operating temp. Before it used to take maybe 15-20min of constant 65mph highway driving but now it takes 30-40min or sometimes never quite reaches there fully. I am not going to fret too much on this though but this seemed to occur around the time I started to get this problem so it shouldn't entirely be dismissed.

FYI - I have not replaced anything on this engine. I still have the same waterpump, thermostat, radiator, etc since 2015 when I purchased it with 30k miles. I feel I should start preemptively replace things but I will leave that for a separate thread.

Any thoughts, recommendations, or suggestions?

[Billfitz]

The heater core and radiator are parts of the same system sharing the same coolant. I'd do a clean and flush of the whole system. Be sure to follow the purge procedure.

[F32Fleet]

Originally Posted by juegomaestro

Vehicle: 2013 BMW 335i Xdrive F30 - 120k miles
Problem: Significantly less heat coming from driver side vents compared to the passenger side.
Dealer's take: Clogged heater core. Replace heater core.

Instead of replacing the heater core, I flushed the heater core independently from the rest of the system. I flushed it forward and reverse, many times. I also poured white vinegar inside the core and let it stand for an hour before flushing it out with distilled water. It took a while as each time I changed flow direction, more chunks of what looked like gold dust or sand kept coming out. Once I started not getting anything more, I reconnected everything and purged the system. My heat returned to full blazing heat (maybe hotter than when I bought it) which is great but slowly over maybe a month, the vehicle returned to the original problem.

I get the feeling that maybe corrosion is coming from other parts of the system (i.e. radiator) and maybe I should replace that, or maybe the heater core is just re-corroding itself again.

I am thinking of trying to use Irontite ThoroFlush on either the heater core alone or the whole system. Has anyone tried using this before? Was it effective? Is it safe? Could it harm the waterpump?

I don't feel like my radiator is bad. I don't have any overheating issues. If anything, it seems to take longer than usual for the oil temp gauge to get to operating temp. Before it used to take maybe 15-20min of constant 65mph highway driving but now it takes 30-40min or sometimes never quite reaches there fully. I am not going to fret too [...]

I've toyed with the idea. The problem is that you can't drain the engine block so that may or may not be an issue. You could buy a small pump and just run 5 gallons of a hot water mix of your dissolver of choice. Duration is up to you. The heater core runs in parallel so the side opposite the in/out connections will experience the least amount of flow. I guess this is why shops have good results by using air to get most of the water out of the core between flushes.

https://www.turnermotorsport.com/p-1...uine-bmw-part/

BOKYWOX 110V NPT3/4'' Domestic Hot Water Circulation Pump 3-Speed Hot Water Recirculating Pump 93W Circulator Pump for Solar Heater/Faucet(RS15/6R) Red https://a.co/d/7IfZRnE

I would also perform a coolant change regardless if you haven't already. There should be no corrosion in the system.

[Revoltos]

That style pump doesn't work very well at all. Not sure if it has to by high up (Like attic or 1st floor) in a central heating system and be installed in a closed system.
About three weeks ago I decided to run some CLR cleaner through my heater matrix, funnily enough, on my 335i which also had very poor heat output in the cabin and takes an absolute age for the engine (oil temp gauge) to warm up. But unlike yourself, my car has a new CSF radiator, new waterpump, thermostat, hoses etc. about 10k ago which included a system clean. The day I carried out the matrix flush was the day I was replacing my trans cooler in a last ditch attempt to get the car to warm up normally. So having to mess around with the coolant system again, I thought i'll try and flush the heater matrix. I seen a guy online fit a pump in a tank of hot water and cleaner and just let it cycle through the matrix. I bought a pump very similar to the one you have shown there and it wouldn't lift any fluid out the tank I had next to the car with the CLR cleaner and hot water in. Very frustrating. I ended up just filling the core with the cleaner and letting it sit there, then going back later with one of those water/air guns you can use with a compressor, I put the water feed hose into the tank and then gently pulsed air/cleaner mix through the core. Rinsed and repeated afew times, but for me, nothing came out.
The result, the car does warm up abit quicker now thanks to the trans cooler change, when it does start to warm I do get good heat inside. There is about an 8 degree difference across the vents now which is fine.
There is something about the cooling system on the 335i that seems to create this slow heating up of the engine and then the matrix seems really prone to either sediment collection or air locks etc.

[F32Fleet]

Originally Posted by Revoltos

That style pump doesn't work very well at all. Not sure if it has to by high up (Like attic or 1st floor) in a central heating system and be installed in a closed system.
About three weeks ago I decided to run some CLR cleaner through my heater matrix, funnily enough, on my 335i which also had very poor heat output in the cabin and takes an absolute age for the engine (oil temp gauge) to warm up. But unlike yourself, my car has a new CSF radiator, new waterpump, thermostat, hoses etc. about 10k ago which included a system clean. The day I carried out the matrix flush was the day I was replacing my trans cooler in a last ditch attempt to get the car to warm up normally. So having to mess around with the coolant system again, I thought i'll try and flush the heater matrix. I seen a guy online fit a pump in a tank of hot water and cleaner and just let it cycle through the matrix. I bought a pump very similar to the one you have shown there and it wouldn't lift any fluid out the tank I had next to the car with the CLR cleaner and hot water in. Very frustrating. I ended up just filling the core with the cleaner and letting it sit there, then going back later with one of those water/air guns you can use with a compressor, I put the water feed hose into the tank and then gently pulsed air/cleaner mix through the core. Rinsed and repeated afew times, but for me, nothing came out.
The result, the car does warm up abit quicker now thanks to the trans cooler change, when it does start to warm I do get good heat inside. There is about an 8 degree difference across the vents [...]

You just have to prime it. Here's a video of the pump in use.

https://youtu.be/LtnVyFNyU1w?feature=shared

It's based off this method via Honda TSB.
https://honda-tech.com/forums/attach...ot-a14-063.pdf

[SilkySmoooth]

You need to flush the heater core both ways. Attach some tubing to each outlet of the heater core and flush it out. Also leave some prestone radiator cleaner in the heater core overnight.
THEN the MOST IMPORTANT STEP!!!
You must vacuum fill the system! A simple fill up will leave air in the heater core! Vacuum filling the system is a must and ISTA states this is absolutely needed. Then of course run the auto bleed procedure .
I had heater core problems a few years ago. Find a post i made regarding this in the past for details on how i fixed this.

[F32Fleet]

Originally Posted by juegomaestro

Vehicle: 2013 BMW 335i Xdrive F30 - 120k miles
Problem: Significantly less heat coming from driver side vents compared to the passenger side.
Dealer's take: Clogged heater core. Replace heater core.

Instead of replacing the heater core, I flushed the heater core independently from the rest of the system. I flushed it forward and reverse, many times. I also poured white vinegar inside the core and let it stand for an hour before flushing it out with distilled water. It took a while as each time I changed flow direction, more chunks of what looked like gold dust or sand kept coming out. Once I started not getting anything more, I reconnected everything and purged the system. My heat returned to full blazing heat (maybe hotter than when I bought it) which is great but slowly over maybe a month, the vehicle returned to the original problem.

I get the feeling that maybe corrosion is coming from other parts of the system (i.e. radiator) and maybe I should replace that, or maybe the heater core is just re-corroding itself again.

I am thinking of trying to use Irontite ThoroFlush on either the heater core alone or the whole system. Has anyone tried using this before? Was it effective? Is it safe? Could it harm the waterpump?

I don't feel like my radiator is bad. I don't have any overheating issues. If anything, it seems to take longer than usual for the oil temp gauge to get to operating temp. Before it used to take maybe 15-20min of constant 65mph highway driving but now it takes 30-40min or sometimes never quite reaches there fully. I am not going to fret too [...]

What did you end up deciding?