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MKIII Heater core DIY:

190K views 201 replies 99 participants last post by  Techguru57 
#1 ·
all right here goes my write up on the heatercore replacement theres a few out there but another cant hurt my car is a 97 gti VR6. I also used the VEMEO replacement from MJM for 34.99
(also thanks to xxxxx who did a write up i didnt want to type everything back out so i used yours sorta )
we will start with the outside first heres go
1. gotta start with liquid to get you through this horrible job

2. Disconnect both rain ducts(covering ecu, and window wiper blade). Each side has about 3 plastic screws.Also take the wipers off
3. Unbolt 2 bolts, one next to the ecu, 10mm nut; and the other right behind the window wiper blade motor, 10mm nut. They aren’t connected to anything,


4. unbolt all little bolts that are behind the flaps on the firewall cover, also there are 2 bolts that are holding the a/c service controls to the firewall, remove those as well. Unbolt 3 13mm bolts from the firewall behind the firewall cover, the one on the left is almost behind the shock tower, kinda hard to get too.




Thats pretty much it for the outside of the car bolts no onto the dreaded inside

Heres a picture take out every screw marked in pink

1.pull off every plastic cover on the dash, as well as take all vents out, also open glove box and remove the 3 screws inside.
2. Unbolt steering wheel nut with 24mm bolt, take off steering wheel, unbolt all sensors attached to steering wheel/airbag.
4. unbolt steering wheel top and bottom plastic cover, 2 bolts from underneath.
5. Then lean the cluster forward and disconnect both harnesses from behind, then take out.
6. Unbolt passenger kick panel( 5 screws from underneath), then pry off slowly(3 clips on top).
7. Take out bolts for airbag cover, 3 or 4 underneath, the slide to the right and pull out.
8. disconnect passenger airbag sensor from behind; take off 4 allen bolts from airbag assembly, 2 on each side. Pull out airbag. )Optional i did not remove my airbag as you can see)
9. remove the center console including unbolting the e-brake. two hidden screws by the rear ash tray/cup holder. Disconnect electronic hatch switch. Then pull up and unscrew handbrake, 2 bolts. Then move out of the way.
10. take off shift knob and boot, unbolt 2 plastic nuts. And then unbolt another plastic nut at the end towards the e-brake.

11. pull out cupholder/console assembly.
12. take out metal cover behind cupholder, around 7-8 holts, 10mm

13. Take off driver kickpanel, 5 bolts underneath, then pull off.
14. unbolt all bolts that hold dash to the rebar, should be around 8-10.
15. unhook all wires that are hooked up to the dash wire clips.
16. Take out dash slowly, and move out of place.
17. unbolt vent right behind rebar, 2 10mm plastic nuts, then unclip from the bottom, and pull up.
18. unbolt vent on top of heatercore housing, 1 screw
19. unbolt footwell vent from the bottom, 1 screw right behind rebar.
20. unbolt 6 clips that hold the heatercore/evap housing together, 2 behind, 2 front, 1 top, 1 bottom, rears are hard to get too, need small screwdriver to unclip those from the back.
21. pull apart heatercore housing from evap housing
22. unbolt the rightside and leftside dash rebar, 2 torx bolts from the outside doorwell

23.Now break out the drill and some bits your gonna have to drill out 2 shear blots that hold the steeering colum to the rebar. once those are drilled out right behind the ingnition swith are 2 -10mm nuts on a bracket holding rebar to firewall take those off. Now you can move reabar out of the way for easy removal of heatercore with no fighting
----replace shear bolts with #8 bolts at 1.25 pitch cost aboust 1.50 at the most

24. pull off the vacuum hose that’s on the heatercore
25. unscrew the heatercore if yours have screws, mine only had 1 holding it up.
26. unbolt a harness that plugs into the heatercore housing, its almost next to the gas pedal , just sits a bit higher to the right.
27. pull back heatercore as far as possible, you will have to use a lot of force to get the heatercore out, just play with it, and make sure you don’t brake anything. .
28. Pull out heatercore by sliding upward, should come out easy.
29. Disconnect the plugs from the heater box and remove from car i did this so i could wash the box out and clean it up.

30. Now replace your foam in the box since its probably gone or soaked.I went to Michaels and bought a .99 peice of foam to recover the blend doors ( i choose green to match my car
) i cleaned off all the old foam and used spray adhesive to attach new foam to the front and back of the blend doors and a little bit of silicone around the edges to make sure it was good and permenant.

This is where i stopped and let the foam sit over nite. At this point i have about 5 hours into the job but i stopped for dinner and to play with my 10 month old so really maybe 3 hours (first time doing the job, but i have replaced dashboards before if that helps)
Evening number 2
is spent puting everything back together just follow the instruction as you took it apart, All the electrical plugs only plug into one thing so you cant screw it up
1st thing i did was put new heater core in ,now my heater core replacement came with plastic cover on the bottom and Foam around the outside. the new one did not fit with the plastic cover on it and the foam got ripped while sliding the new one in so i just ripped it off.
and thats it for replacing it if you got this far awesome not you get to put it all back just take your time and have a beer.

Oh and i spent maybe 4 hours the 2nd night but at leaset an hour of that was trying to figure out where a plug went ( white one that attaches to the ac/heat controls ) and while looking at it pounding quite a few beers so progress slowed down


Modified by smi2710 at 11:14 AM 12-11-2009

Modified by smi2710 at 11:15 AM 12-11-2009


Modified by smi2710 at 11:18 AM 12-11-2009
 
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#3 ·
Re: MKIII Heater core DIY: (smi2710)

e wish this DIY was available when I did my A/C evapourator replace last year. It took me forever to remove the knee bar - didn't know about the two hidden bolts behind the ignition switch holding the bar to the steering column bracket.
This job has to be possibly the biggest PITA on a VW.
 
#4 ·
FV-QR

tiny bit off topic but the hell do you get the screws back in that go behind the air vent grilles. ive had mine unbolted for almost 2 years not and would like to finally get my dash all screwed down. havnt looked into pulling the grilles out so maybe u have my answer
great writeup by the way. i know my time is coming soon
 
#39 ·
tiny bit off topic but the hell do you get the screws back in that go behind the air vent grilles. ive had mine unbolted for almost 2 years not and would like to finally get my dash all screwed down. havnt looked into pulling the grilles out so maybe u have my answer
great writeup by the way. i know my time is coming soon
-Take the vent out
-Screw in the screws
-Pop the vent back in

:beer::thumbup:
 
#5 ·
Re: FV-QR (dankvwguy)

Quote, originally posted by dankvwguy »
tiny bit off topic but the hell do you get the screws back in that go behind the air vent grilles. ive had mine unbolted for almost 2 years not and would like to finally get my dash all screwed down. havnt looked into pulling the grilles out so maybe u have my answer
great writeup by the way. i know my time is coming soon

magnetic screwdriver.
 
#8 ·
Re: FV-QR (Dutchsider)

Quote, originally posted by Dutchsider »
Awesome.
I was just contemplating this today as my heat does not feel as hot as it should be

Disconnect the bottom ends of hoses leading to the heater core on the inside of the engine bay. Connect a water hose to the intake inlet. Then connect a drain hose to the other side. So that you don't flush everything in your heater core on to your engine and all over your engine bay.
Directly flush your heater core for a minute or two. Starting with low pressure then turning up the water pressure.
You might have some blockage that you could flush out instead of installing a new core and going through this process.
Definitely a must for anyone who's heat does not feel as hot as it should. Who have been thinking that it might be the heater core.
Good luck, Matt.
 
#9 ·
Re: FV-QR (IloveMyCar32)

Quote, originally posted by IloveMyCar32 »

Disconnect the bottom ends of hoses leading to the heater core on the inside of the engine bay. Connect a water hose to the intake inlet. Then connect a drain hose to the other side. So that you don't flush everything in your heater core on to your engine and all over your engine bay.
Directly flush your heater core for a minute or two. Starting with low pressure then turning up the water pressure.
You might have some blockage that you could flush out instead of installing a new core and going through this process.
Definitely a must for anyone who's heat does not feel as hot as it should. Who have been thinking that it might be the heater core.
Good luck, Matt.

i will say that my heat is not as hot as it was before replacment of new core but i havent flushed the system yet, all i did was add more fluid and im sure i have a air bubble or ten but low heat is way better then steamy windows but i want the burn my fingers heat.
 
#10 ·
Re: FV-QR (IloveMyCar32)

Quote, originally posted by IloveMyCar32 »

Disconnect the bottom ends of hoses leading to the heater core on the inside of the engine bay. Connect a water hose to the intake inlet. Then connect a drain hose to the other side. So that you don't flush everything in your heater core on to your engine and all over your engine bay.
Directly flush your heater core for a minute or two. Starting with low pressure then turning up the water pressure.
You might have some blockage that you could flush out instead of installing a new core and going through this process.
Definitely a must for anyone who's heat does not feel as hot as it should. Who have been thinking that it might be the heater core.
Good luck, Matt.

http://****************.com/smile/emthup.gif
 
#18 ·
Re: MKIII Heater core DIY: (smi2710)

Quote, originally posted by smi2710 »

23.Now break out the drill and some bits your gonna have to drill out 2 shear blots that hold the steeering colum to the rebar. once those are drilled out right behind the ingnition swith are 2 -10mm nuts on a bracket holding rebar to firewall take those off. Now you can move reabar out of the way for easy removal of heatercore with no fighting
----replace shear bolts with #8 bolts at 1.25 pitch cost aboust 1.50 at the most

Wouldn't it be easier to just remove the steering column from the u-joint?

And thank you for pointing out where every screw and bolt is, I hate forgetting one and wasting time looking for it.


Modified by Unit01 at 6:09 PM 12-17-2009
 
#22 ·
Re: FV-QR (smi2710)

Quote, originally posted by smi2710 »
you dont if disconnect the AC lines but i chose not to so i didnt have to refill the freon

You don't have to take the a/c lines off either lol. Pull the dash rebar out and use a pry bar to pull the assembly back just far enough for the core to clear the dash bulkhead.Works like a charm everytime.
 
#23 ·
ok

i gotta say, this thread saved my life....cold, cold winter this year, and no heater really started to get old... the walkthrough is very accurate, though the pics get less and less near the end.
I wanted to throw some extra tidbits that I came across while doing this that may help the next guy;
the whole shear bolt thing kinda bugged me, and for me, i was afraid of getting to the point of no return, and not having the correct bolts for it, so, i worked around the problem....if you unbolt the dash support as if you are taking it out, but leave the shear bolts in place, you can pull the support out and swing it kinda clock-wise in the car...since the steering column is on a universal joint, it will swing with the dash support. i unbolted the bolts from around where the a/c comes through the firewall allowing the a/c tubes to kinda come through. this let me pull the whole heater box back far enough to get the core out/in. oh..and my core didn't have the little vaccum fitting in it, you have to pull it out of the old one...do this before you put the dash back together...lol...trust me
hope that helps
 
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