MK4 heater core

[oldpoopie]

Whew. Just finished doing the heater core on a 99 jetta. Wow what a pain.
Here are a few tips. Dont forget the one large bolt holding the cross member on underneath the wiper motors. Unbolt the heater box completely, but dont disconnect the AC lines. You can pull the box away from the firewall just enough to swap out heater cores.
Label all the plugs so you know where they go during re-assembly. Even if its just a little sharpie on there.

Total time was about 8 hrs including about an hr for lunch. It would have taken much much longer had nick not been helping.

I'm hoping that I never have to do it again, so dont ask for a howto! LOL

 

[compu_85]

At least you didn't have to drain the AC! It takes less time on the older cars, but you need to drain the AC to do it properly. Did the whole dash have to come out?

Now we just wait for the day when the foam on the blend doors starts blowing out and you loose head because of that.

-Jason

 

[oldpoopie]

yep. Dash, support bar, EVERYTHING had to come out. It was a pain. I kept warning Nick that it was going to be difficult. I dont think he realized... LOL. I also have to mention the extraordinary patience that his son had, sitting relatively quietly the whole time we worked.

 

[mrGutWrench]

(snip) Total time was about 8 hrs including about an hr for lunch. It would have taken much much longer had nick not been helping.
I'm hoping that I never have to do it again, so dont ask for a howto! LOL

__. That's about what we'd expect for a heater core replacement back "in my old life" (Land Rovers) but it's still pretty scary. I'm just hoping that I don't have to do one of those.

__. On the other hand, doing the blower motor is pretty easy. It requires pulling the center console to remove the glove box, but it's a simple "screwdriver and socket" job.

 

[Ian F]

This seems to be common with newer cars. The heater core and/or blower motor are installed on the assembly line first, then the entire car is built around them. I've read similar stories of replacing the blower motor on Volvo 240's... 8 hours is considered "quick."

 

[tperretta]

Im going to be doing this tonight. Never done one, so if anyone has anyone other advice, shoot it my way. Im just gonna start pulling stuff out until I get to that little booger.
NOT looking forward to this job!

 

[oldpoopie]

Take your time. Lable the elec connectors on the harness and the heater cables so you know where they go when u put it back together. Take the rain tray out. There is 1 bolt behind the wiper assembly that must come out. Disconnect the bolt at the ac pass thru but don't evac the ac. You should be able to pull the airbox assembly out enough (with help) to R&R the heatercore without messing with the ac.Ill try and check in every now and then. Post if u have any probs.

 

[tperretta]

Take your time. Lable the elec connectors on the harness and the heater cables so you know where they go when u put it back together. Take the rain tray out. There is 1 bolt behind the wiper assembly that must come out. Disconnect the bolt at the ac pass thru but don't evac the ac. You should be able to pull the airbox assembly out enough (with help) to R&R the heatercore without messing with the ac.Ill try and check in every now and then. Post if u have any probs.

Thanks oldpoopie

 

[ymz]

Go through this thread:
http://forums.tdiclub.com/showthread.php?p=1967465

Yuri.

 

[jasonTDI]

You guys too...mine just showed up.

 

[tperretta]

I need someone to verify If Im removing this large crossmember type bar going across. Ive already started removing bolts but it appears to be a pretty big pain to take off. Just need to make sure Im not making this more difficult than it should be.

Also, could someone verify where the core is actually located? Im assuming its behind the heater box assembly in the center.... (behind the radio cage).

 

[oldpoopie]

remove that crossbar. youll have to unbolt one bolt from behind the wiper assembly from the outside. Also dissconect the steering column from the crossbar. Once that is out, you can loosen the heater box from the firewall and gently pull the center side away from the firewall. The heater core will unscrew and pull up and out of the heater box. ( I wish I had taken pictures but we were on a tight schedule)

 

[tperretta]

remove that crossbar. youll have to unbolt one bolt from behind the wiper assembly from the outside. Also dissconect the steering column from the crossbar. Once that is out, you can loosen the heater box from the firewall and gently pull the center side away from the firewall. The heater core will unscrew and pull up and out of the heater box. ( I wish I had taken pictures but we were on a tight schedule)

Thanks oldpoopie, that's what I figured. I already have all the bolts off the crossbar except the ones on the column..... So, it sounds like im on the right track.

 

[macdave]

Do you have any idea what causes them to fail? It would be nice to avoid having to replace one.

 

[tperretta]

Heater cores fail on all cars. .. It's usually just a matter of time. Im guessing corrosion... just normal wear and tear on the system.

Im not sure if mine was just ready to go or my 25lb tune may have pressurized the system and helped it fail prematurely. I'm lowering my boostvalve setting once I finish this job!

 

[tperretta]

How do you actually get to that one bolt right behind the steering column/crossbar??? I think it's the one oldpoopie was mentioning that's near the wiper assembly.
Looks like I have to get the plastic cowl off... But How do I get it all off w/out breaking the plastic? looks like it's siliconed onto the windshield pretty good.

 

[oldpoopie]

the plastic cowl must be removed, then the wiper motor assembly comes out. Then you have access to the bolt.

 

[tperretta]

the plastic cowl must be removed, then the wiper motor assembly comes out. Then you have access to the bolt.

Is there a trick to remove it? It seems like it's sealed pretty well....

and once it's removed, what do I use to seal it back up to the windshield?

I have silicone...Is that good?

 

[jasonTDI]

You pull the wipers and pull up the plastic. It just pulls off.

 

[compu_85]

Wrong coolant goes a long way to helping a heater core down the road of failure.

-J

 

[tperretta]

You pull the wipers and pull up the plastic. It just pulls off.

I started prying around shortly after that question and figured it out. I thought I was breaking it at first.... but im good now.

 

[merkerguitars]

Takes me about 8 hours to do one to, when I did one on my bosses 99.5 Jetta I had the following tricks.

Vacced out the AC system, the heater box was FULL of coolant

Just loosen up the cross bar and bend the bracket to the left of the passenger side airbag and the box comes right out.

 

[tperretta]

Takes me about 8 hours to do one to, when I did one on my bosses 99.5 Jetta I had the following tricks.

Vacced out the AC system, the heater box was FULL of coolant

Just loosen up the cross bar and bend the bracket to the left of the passenger side airbag and the box comes right out.

How many screws hold it in place? Ive started loosening many screws that look like they will allow the whole assembly to split into a top and bottom half. It looks like im wrong on that. Its starting to look like there is a seperate compartement for the core but I haven got the crossbar far enough out of the way to get to it. The insulation is a pain and so is that crossbar. I cant see much until i get those out. ...

That's waiting util tomorrow.

 

[tperretta]

BTW, Im doing this w/out a manual. I think I'd do it in 8-12 hours if I had a manual but right now Im spending too much time cautiously debating removing things that im unsure of. Getting it back together will be a lot quicker since I'll know what im actually doing.

 

[tperretta]

Hopefully someone can shoot me a quick tip here...

Im stuck on getting the heater box to swing away from the firewall. it doesnt appear possible to get the core out unless the can swing out somehow for more room. It looks like it's screwed to the firewall.

Ive got the lid for the core popped up a bit and all I need now is a way to swing the box out somehow. Can somehow steer me towards what I should do next?
Thanks so much. Oldpoopie youve been a big help and thank you to everyone else too.

 

[oldpoopie]

Its screwed to the firewall from the back side. Take the intake pipe out, you'll see some oval cutouts in the heat shielding. Bend it back and you can loosen the fasteners. If memory serves there are 4. (one is kinda hidden under the ac lines.

 

[oldpoopie]

how'd ya do?

 

[tperretta]

how'd ya do?

Got it out and compared it to the core I bought from NAPA. It looks to be of lesser quality so im going to have to wait until next week for my VW core to arrive.
I couldnt risk putting a low quality one in that may leak in a year or two and then have to do this fun job again.

thanks so much for the help!

 

[oldpoopie]

ahhh.

 

[jasonTDI]

How much was the NAPA one? My VW one was $155 from the dealer.