How to: Replacing 2012+ NMS Passat heater core

BKmetz

Administrator, Member #10
Staff member
Joined
Sep 25, 1997
Location
Illinois
TDI
2015 Passat, titanium beige, 6MT
You guys are getting the wrong idea. This thread is about the heater core issue that only effects the NMS Passat.

I've been looking around for a how-to on replacing the coolant (for good measure, and to perhaps prevent clogging of the heater core in the first place), or the drain and refill needed before and after the heater core replacement.

I saw the term vacuum fill in another post, and searching for that, I found some commercial tools, as well as a recommendation in TDI 101 (for A5s) to refill by filling the overflow tank and pulling slight vacuum on the upper tank hose.

Assuming this works on the NMS, could one also use this method to cleanly drain a sizable fraction of the coolant on the engine side (as opposed to radiator side) of the thermostat?
The NMS Passat heater core issue is being cause by excessive solder flux left in the heater core. This is a manufacturing defect. This is not going to happen to any A5 model. Hell, I had to repair the heater box blend doors on my old B4 at 300k miles and I replaced the heater core as a precautionary measure. It was perfectly clean inside.

so, this post seems like a total piece of cake in comparison to this other post http://forums.vwvortex.com/showthread.php?4188858-DIY-MK-IV-Heater-Core-Replacement
so, which is it? I feel like I can do this on my own based on this post, but the linked post makes me feel like I SHOULD take it to a professional!!
Again, you're comparing a NMS Passat with a completely different car. The dash does not have to come apart on the NMS Passat to replace the heater core. It is much easier. For a MK4, it's as complicated as it looks.

As I had the plugged heater core and low heat on the passenger side, I bought a new heater core and clamps and was planning to do this myself. In the end I took my car to the dealer and had the heater core replaced per the procedure outlined in the TSB. What made me change my mind was that I do not know how to flush the Passat system properly. There have been NMS Passat owners who had the heater core replaced per the TSB and they still had to take the car back for another plugged heater core because the system wasn't flushed correctly. I don't know if this was bad luck or dealer tech incompetence. In any case, I'm only paying for this job once and I now have a warranty on the parts & labor if it happens again.

:)
 
Last edited:

BakoTDI

Veteran Member
Joined
May 5, 2005
Location
Bakersfield, CA
TDI
Jetta, MK7
oh I see!! The panels removed seemed just like the ones in my MK4 jetta...sorry for the confusion but thanks for the clarification! I guess I'll have to go back to the drawing board! :(
 

jrm

Veteran Member
Joined
Jul 24, 2013
Location
Oregon
TDI
2013 Passat SE with nav (totaled)
Picked up a IR thermometer, after 10 miles of driving at 25F outside the drivers side was 135F, center left 140F, center right 144F, passenger side 105F :eek:
 

rynec

New member
Joined
Jan 6, 2016
Location
Central NY
TDI
14 Passat TDI
Does anyone know how much coolant I will lose when pulling the old core?

I am having the same issue with the heat and at 48k miles. Figured I would just change it myself as it doesn't look that hard. Just did an O2 sensor a few weeks ago- shocked about how many repairs for such a new car.
 

VeeDubTDI

Wanderluster, Traveler, TDIClub Enthusiast
Joined
Jul 2, 2000
Location
Springfield, VA
TDI
‘18 Tesla Model 3D+, ‘14 Cadillac ELR, ‘13 Fiat 500e
Does anyone know how much coolant I will lose when pulling the old core?

I am having the same issue with the heat and at 48k miles. Figured I would just change it myself as it doesn't look that hard. Just did an O2 sensor a few weeks ago- shocked about how many repairs for such a new car.
You will lose all of it since you need to flush the cooling system prior to removing the heater core. You will need to refill the system with fresh coolant after you install the new heater core.

Failure to properly flush the system will result in the new core clogging quickly.
 
Last edited:

767wrench

Veteran Member
Joined
Jul 25, 2012
Location
Ohio
TDI
1981 Rabbit Pickup
Ive gotten some questions about flushing and whether or not my core is still working so Ill share some of my experiences. I have about 10k miles on since the replacement.

One thing I did differently than most was I flushed my car completely and then used green coolant. Many other members frown upon this but here is my reasoning;

There are many different types of coolant. More than I was even aware of until this project. Everyone says oh green is for iron block and heads and you can only use whats specified from the dealer. Its not entirely true in my opinion. This article is a good read on coolant types;

http://www.popularmechanics.com/cars...o/a91/1272436/

So the green coolant I used is Prestone 150k mile mix with any make and model. Its an organic acid type coolant for aluminum like the stock passat G12/13. I contacted Prestones tech dept and they say it is absolutely compatible. I would still be sure to do excessive flushing of the system first as its never a good idea to mix colors normally. Also the issue of Diesel cavitation erosion gets brought up. I did a lot of reading on that too. Old powerstrokes had additives that needed replenished and tested. The newer coolants have them in them though. I inquired about this to Prestone and he assured me that the 150k yellow bottle Prestone was compatible. He seemed to know his stuff and went over my head with technical info on the different coolant types.

So when I flushed mine it was difficult to get all the pink coolant out. Just removing the upper radiator hose and letting it run while keeping the reservoir full wasnt enough. I also disconnected the intercooler lines and fed them withba garden hose and more goldish brown goo came out of there.

So finally, yes my core is still working excellent and one more reason I like green coolant over pink. I have an egr delete on my car which involves splicing together coolant lines for the heater core. My first setup was two male brass nipples screwed into a double female pipe thread connector. The fittings were tight and i used thread tape but they still dripped just a few drops here and there. (guy at the hardware store said cheap chinese brand was the reason. I since got a better fitting unit) Then after a while I noticed it formed a pink crusty goo and barely leaked at all. As soon as i installed green coolant the thing was leaving small puddles everywhere. I think the pink coolant has a tendency to gel /crust up. And ive heard bad stories of people replacing multiple cores that keep clogging but mine is good! Now if you're under warranty and want to stay that way then youd better use the g12/13 vw coolant. However I never found vw very helpful with anything and the work i did let them do was crappy at best (turbo fod damage, misaligned steering wheel, uncharged AC, clutch warranty refusal at 50k) so I make the car work for what I need it to do! Like many say you pay to play so the choice is up to you. I may face catastrophic corrosion someday( i doubt it) but in my opinion the pink g12 wasn't working for me!

Also a disclaimer i dont plan on selling my car anytime soon so resale with green coolant to me isn't an issue. If the person was even knowledgeable enough to know the difference.
 
Last edited:

jrm

Veteran Member
Joined
Jul 24, 2013
Location
Oregon
TDI
2013 Passat SE with nav (totaled)
very few people know about Diesel cavitation erosion, its a real thing with sleeveless blocks- seen a hole threw the water pump on a Ford 6.0 strait into the block dumping coolant right into the oil- the best green style (non OAT) coolant is Fleet charge, it has SCA's for diesels. They also make Final charge and that's just another OAT coolant.
I use fleet charge in all my iron head diesels:
http://www.peakhd.com/product-lines/fleet-charge/sca-precharged-coolant-antifreeze/
 

Shawn MacAnanny

Veteran Member
Joined
Sep 29, 2013
Location
Felton, DE
TDI
2012 Passat TDI SE
Be careful with diesel coolants claiming safe for aluminum, I am shocked at the pH of coolant being used in aluminum. Looking at that build up I'd be interested to test it. I am wondering if it's a silicate build up? That's usually what the run to protect the aluminum in a high ph environment. The high pH protects steel but damaged aluminum. 8.5 max for aluminum, 200 ppm sodium molybdate, and 2000 ppm sodium nitrite to protect steel. That's generally what's in good coolant. I've found diesel aluminum compatible coolants at 11.0, 0ppm molybdate, and haven't found one under a pH of 10.0. I think there will be some major changes coming about with the glycol being used in aluminum engines.
 

kylierose

New member
Joined
Dec 16, 2015
Location
Pittsburgh, PA area
TDI
2013 Passat SE TDI
Heater Core Replacement Cost from VW

I just received a quote from VW in the Pittsburgh area... ~ $ 1,400 for the replace/ flush job. Monroe muffler does have a job code for this and they asked for ~ $ 450... This with me providing the parts and G13 coolant. I've ordered my heater core and will perform installation once it arrives.
 

767wrench

Veteran Member
Joined
Jul 25, 2012
Location
Ohio
TDI
1981 Rabbit Pickup


Got another better picture of the clog now that the bandsaw is fixed. The aluminum underneath doesn't look pitted or corroded in my opinion. This stuff is just a soft sticky dust of some sort. Idk if I buy the whole flux/corrosion theory yet.
 

jrm

Veteran Member
Joined
Jul 24, 2013
Location
Oregon
TDI
2013 Passat SE with nav (totaled)
how many of us went threw the GM dex-cool issues in the 90's
Exact same looking goo
 

BKmetz

Administrator, Member #10
Staff member
Joined
Sep 25, 1997
Location
Illinois
TDI
2015 Passat, titanium beige, 6MT
I had my heater core replaced per the TSB last November. Finally got around to dissecting it. I used a Dremel Tool with an abrasive cut-off wheel.

Almost done cutting one side.


You can see how the heater core is progressively more crudded up going from the right side (clean) to the left side (plugged up). This view is the top of the heater core as it would be positioned in the car.


Close up of the top right side (clean side).


Close up of the top left side (plugged side). The debris was like a sludge. The water evaporated out within a few minutes and left a dark colored crust.


To give one an idea of how small those coolant passages are, that Ace Rewards card BARELY fits in the gap.


The heater core still had some coolant in it and it was dripping out after I cut the end off. I wiped up the wet stuff and it was quite nasty looking. The water evaporated and left the dark colored crust again. The black specks are the cut-off wheel grit. The silver specks are aluminum grit.


More pics in the next post.

:)
 
Last edited:

BKmetz

Administrator, Member #10
Staff member
Joined
Sep 25, 1997
Location
Illinois
TDI
2015 Passat, titanium beige, 6MT
Now we move on to the bottom side of the heater core. There is more pluggage than the top side. I don't know if the coolant flow is top to bottom or bottom to top. Either way when the car is off any debris is going to settle on the bottom.

Again we see the right side is rather clean and the left side has a lot of sediment.


Close up of the right side. Again the cut-off wheel and aluminum bits left a lot of grit which makes the inside look dirtier that it really is.


Close up of the left side. What is interesting is how easy that sludge cleans up. I took a cotton swab to that last row and it cleaned right up. I have no idea how it would clean up after it dried or if the passages could be cleaned.


The sediment on the bottom end piece. Again, the black and silver flecks are cut-off wheel and aluminum grit.


My take-away is that IF the problem is caught early enough, and IF a proper flush is performed, this should be a one-time job. Of course one doesn't know how bad the heater core is unless you get the old one and cut it apart.

:rolleyes:
 
Last edited:

Sibirian

Member
Joined
Feb 15, 2015
Location
Dayton, OH
TDI
2013 Passat
I replaced my heater core myself but now I lost all heat. Before replacing I had some heat on driver side but now even driver side is blowing cold air. I checked lines connected to the core are they extremely hot.

Any suggestions on what I could have accidentally unplugged or what could be causing this?
 

nord

Veteran Member
Joined
Mar 5, 2010
Location
Southern Tier NY
TDI
All turned back to VW. Now a 2017 Hundai Tuscon. Not a single squalk in 10k miles.
Problem is almost certainly NOT the core. The problem is with the install. Core is not positioned all the way in place. This causes the door actuator to bind. Thus, no heat, all heat, or whatever position the door happens to be in when it became stuck Do not be afraid to press the core into position! Once done, then cycle the heat from full off to full on several times. The plastic or nylon actuator should move smoothly over its full range. Place the black plastic cover back on, make sure all fasteners are bottomed out and no binds in the actuator. All will be well.

Oh... Ask me how I know. I'm not proud to have learned the hard way.
 

YukonLT

Veteran Member - TDIClub Enthusiast
Joined
Nov 28, 2012
Location
N/A
TDI
2010 Golf TDI 6MT
I replaced my heater core myself but now I lost all heat. Before replacing I had some heat on driver side but now even driver side is blowing cold air. I checked lines connected to the core are they extremely hot.
Any suggestions on what I could have accidentally unplugged or what could be causing this?
Same thing happened to me. Ended up just being a bubble in the lines. Try squeezing the rubber lines a few times to get the fluid moving and work the bubble out. That's what worked for me and my car has incredible heat now :D
 

BKmetz

Administrator, Member #10
Staff member
Joined
Sep 25, 1997
Location
Illinois
TDI
2015 Passat, titanium beige, 6MT
After reading about all these complications I'm glad I had the dealer do the heater core work. I had to wait a few months for reimbursement from VW but it was worth it.

:)
 

767wrench

Veteran Member
Joined
Jul 25, 2012
Location
Ohio
TDI
1981 Rabbit Pickup
I replaced my heater core myself but now I lost all heat. Before replacing I had some heat on driver side but now even driver side is blowing cold air. I checked lines connected to the core are they extremely hot.
Any suggestions on what I could have accidentally unplugged or what could be causing this?
Just above where you install the heater core, there is a white plastic arm on a shaft. Nothing holds it on and it can be knocked off. I did it and had a similar issue now that you mentioned it. I bet that's your problem. I just fiddled with mine until it seemed like it was fully seated on the shaft again and everything went back to normal. You can watch the arm move when you change settings /Temperature
 

Sibirian

Member
Joined
Feb 15, 2015
Location
Dayton, OH
TDI
2013 Passat
Got my car scanned this morning and got the following code

9477489 - Motor for Air Distribution Flap
B109D 71 [008] - Actuator Stuck
 

nord

Veteran Member
Joined
Mar 5, 2010
Location
Southern Tier NY
TDI
All turned back to VW. Now a 2017 Hundai Tuscon. Not a single squalk in 10k miles.
Umm... I was correct! No big deal really and an easy fix.
 

VeeDubTDI

Wanderluster, Traveler, TDIClub Enthusiast
Joined
Jul 2, 2000
Location
Springfield, VA
TDI
‘18 Tesla Model 3D+, ‘14 Cadillac ELR, ‘13 Fiat 500e
Got my car scanned this morning and got the following code
9477489 - Motor for Air Distribution Flap
B109D 71 [008] - Actuator Stuck
That confirms nord's diagnosis. Easy enough to fix.
 

Sibirian

Member
Joined
Feb 15, 2015
Location
Dayton, OH
TDI
2013 Passat
control lever arm was not set all the way in, therefore it did not open actuator. less than 1 hr after start i had great heat again.
 

MichaelB

Veteran Member
Joined
Aug 11, 2009
Location
SE Wisconsin
TDI
2014 Passat SE DSG
control lever arm was not set all the way in, therefore it did not open actuator. less than 1 hr after start i had great heat again.
This is the kind of stuff that makes this forum great. Not all the dieselgate complaining. Motor on.
 
Last edited:

Sibirian

Member
Joined
Feb 15, 2015
Location
Dayton, OH
TDI
2013 Passat
So after I took my dash off, I started my car and could see lever moving back and forth when switching from heat to cold. When I pulled it, it came out without any force, that is when I realized that it was not set in there all the way. The hardest part was trying to figure which way it is supposed to go in. What I ended up doing was to remove the white piece that sits in from the arm and sit it by itself. This worked better because I realized that I was trying to sit it in the wrong position. After the white piece was placed in, I just had to change temperature to get the arm to move to the right position to connect back to the piece.

----------------------------------------------------
off-topic ramblings:
what dieselgate complaining? I could care less about the claims that US government been making about the VW population. I have yet to see one actual test result with concrete numbers proving anything that news is reporting. Our cars do not produce all the crazy black smokes like every diesel truck out there that seem to be running fine without any DEF fluids. This whole incident proves that government cares more about money than anything else. Environment and all other things only matter to get public stirred up if the government wanted to actually protect the environment they would work with car manufacturers to get us cars that get 100miles per gallon instead of most cars getting only 30 miles per gallon. Also what about all those diesel trucks that get 5 miles per gallon, you can't tell me that my car that used DEF and recirculates exhaust gasses and only burns 1 gallon for every 40+ miles is worse polluter. This whole thing is just a political game.
Sorry for off-topic ramblings.
 
Top