Symptoms of Bad Heator Core- B7 TDİ

Hi there.
Recently had a post about losing a coolant, and the dealer said I drive 3k+miles a month it is normal. I don't believe this. I should not refill 2-3 oz a week.
After reading some posts about bad heater cores, I realized my air vents do not blow the same warm air, the ones in the center above radio unit is very weak. So I set up an appointment for next week requesting heator core replacement.
This post may help others with same problem as I was looking for a reason why I lost coolant for months.
According to some other posts, this is a cronic problem for B7 TDI.
- Window fogging,
-Coolant loss are some of the symptoms.

Could other forum members share how was their experiences with heater cores, how many times did they replace and what are the symptoms they encountered?
I hope will be an informative post for all members, as we see many new posts about heater cores.
Thanks!

Hi there, I've been attempting the heater core fix myself today. My car's a gasser but the symptoms for me seem to be the "classic" symptoms for diesels as well: lack of heat. It sounds like you're experiencing those issues.

However, I'd expect if you're losing coolant, there'd be a noticeable odor of coolant in your cabin, especially at the rate you're losing it. I don't agree that 3K miles per month would point to ANY coolant loss normally, though maybe I'm not aware of something in VWs or diesels.

Next time you're in the car, do you notice a sweet smell in the cabin?

MostroDiesel said:

Hi there, I've been attempting the heater core fix myself today. My car's a gasser but the symptoms for me seem to be the "classic" symptoms for diesels as well: lack of heat. It sounds like you're experiencing those issues.

However, I'd expect if you're losing coolant, there'd be a noticeable odor of coolant in your cabin, especially at the rate you're losing it. I don't agree that 3K miles per month would point to ANY coolant loss normally, though maybe I'm not aware of something in VWs or diesels.

Next time you're in the car, do you notice a sweet smell in the cabin?

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I actually had that smell before but they replaced the AC evaporator or compressor I'm not sure and it fixed it. They said there was a leak. After that no smell.
I'm worried that they will say my heater core is fine and try to charge me diagnosis fee. Maybe I should wait until the heat is gone?

How is the vent on the outer passenger side (hot or cold)? What color is your coolant (bright pink or orange/clear)? Mine has had the heater core replaced twice, no coolant loss either time, the second time i had a puddle 10 days later because the water pump was leaking when it was running.

On my '13 the heater core clogged up such that the car had little heat especially from the passenger side by about 25,000 miles.

My wife refused to ride in the car in cold weather - can't blame her.

Look for deposits forming in the coolant fill bottle. If you see them, and have poor heat, chances are your core is clogged and should be replaced under the warranty.

I had no coolant leaks, or smells inside the cabin.

06bluebeetletdi said:

How is the vent on the outer passenger side (hot or cold)? What color is your coolant (bright pink or orange/clear)? Mine has had the heater core replaced twice, no coolant loss either time, the second time i had a puddle 10 days later because the water pump was leaking when it was running.

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Passenger side is blowing cold and the coolant appears to turn orange color. Still more like pink/orange tho not close to yellow.
I made an appointment for tomorrow morning, put in the appointment notes that it is most probably heater core issue I hope they had some similar cars in before.

Another possible cause of coolant loss is a fitting in the engine bay. My 2015 had a slow leak there and over time the effect was like a heater core going bad. So if this fitting is bad the heater core itself actually may be fine. Problem became evident when passenger side vent blew cold, then center vents followed by driver's side vent which mimics how a failed heater core operates which misled me to think the core was going bad.

Just happened to me yesterday where the coolant warning light came on. Dealer figured out it was the fitting - showed me where it was leaking. Fitting is by the firewall towards driver's side, easily seen with hood open. Sorry - have no picture as car is still at dealer waiting on new fitting.

Yes, the 2012-2014's had a heater core issue. I know because the 2014 I had needed the core replaced. To date from what I've read here only one 2015 has had a heater core fail.

I know my experience with the fitting on my 2015 may or may not apply to the OP's car. Wanted to add it here in case it helps any NMS owner with heat/coolant issues look at possible causes. So check the fitting - may not need to replace the heater core!