Heater core replacement

[duje]

I'll try to explain how to replace heater core without removing the dash
So let's start
The watch is just to show you that this is more or less simple few hour job

I'm starting to dissmantle drivers side leather trim piece underneath the steering wheel

And small carpet trim next to centre console

Now you can see clips holding the heater core housing in place

Than take out centre console, and fresh air grill above it (I wont explain how because this is a straight forward job, and I think everybody did it)

Cut all the zip ties that are holding cables

If you have electric steering column, you'll need to unscrew the module that is just on top of the core housing

Now you can see 2 more clips on top of the housing cover

Take apart passangers leather trim underneath glovebox (2 plastic clips under the glovebox)

Unscrew the glovebox lock

Take out the upper and lover glovebox

Also dissmantle the brackets on the bottom of the core housing

Taking out the lower glovebox

There is a screw inside the console that holds left side of the glovebox

There is a bracket on the drivers side that needs to go out

Now it's time to take the clips out, 4 on top and 2 on each cover side

This is passanger side clip

Top side clip (drivers side is tricky)

Disconnect temperature sensors on each side and pull the cover out

First sign of leaking coolant

Here's the core and notorious pipe (usually it fails)

Unscrew the pipes from heater core

This one is a bit complicated

But nothing that few extensions couldn't fix

Put a rag on the floor or it will be wet very soon

And the core is out (this is the only way that can get out)

Keep it in upright position or you'll loose 5 small nuts that you need for new core

An hour later and core is out of the car

Old and new, new ones are black just like expansion tanks

Lots of parts, but much less when taking out the dash

New pipe and o rings, notice 5 small nuts that need to go on new core, I used some vaseline on o rings before assembly

[duje]

Nuts are on the core

Now I connected HVAC controls and started the car, heat is on

Pour some new coolant in the car and open the vent screw

Car warmed up and bubbles are getting out

When air is out, check the core/pipe connections for leaks and put everything back together

This is the only way that cover will go back in

Clips and new zip ties are back
And now the easy part, put all the parts back in

[Timm]

Thanks for the write-up Duje, and for taking the time to take the photographs. The job doesn't seem so scary now!

[bRIZZAd]

Now where's the photo of your wristwatch and the finishing time? Excellent work!

[TxGR8White]

It is not that simple. What is not shown in these pictures are both driver and passenger side dash support tubes which run from either side of the top of the dash towards the center console and down in front of the heater core cover. It is the tubes that prevent the heater core from just coming off. Either the EURO cars don't have this (doubt it), or the tubes were taken off the last time someone was back there to apply all that epoxy gooo to the double black tube you see in the pics.
You can do the core exchange without taking out the dash, but for the rest of the 8 population, it is more work than what is shown here. I have it down to about 4 hours from start to finish (I "modified" my dash supports to be able to just unbolt the piece that is in the way)..

Nice write-up though...

[duje]

Now where's the photo of your wristwatch and the finishing time? Excellent work!

3,5 hrs total, but I finished everything in the late afternoon because I needed to take my girlfriend to the beach in the meantime, she wouldn't be happy if I spent my day off only on the car .

It is not that simple. What is not shown in these pictures are both driver and passenger side dash support tubes which run from either side of the top of the dash towards the center console and down in front of the heater core cover. It is the tubes that prevent the heater core from just coming off. Either the EURO cars don't have this (doubt it), or the tubes were taken off the last time someone was back there to apply all that epoxy gooo to the double black tube you see in the pics.
You can do the core exchange without taking out the dash, but for the rest of the 8 population, it is more work than what is shown here. I have it down to about 4 hours from start to finish (I "modified" my dash supports to be able to just unbolt the piece that is in the way)..

Nice write-up though...

I have black pipe support only on drivers side, and I glued that pipe before, if there was a support on the passangers side there's no way that core would go out

[Wuffer]

Glued?

[IcemanBHE]

Threads merged. Nice pics n stuff. Thks

[duje]

Glued?

I used a soldering iron to weld it and 2 component stuff that is used to seal the ruptured exhaust pipes, it was good for over a year now, but it failed again on the same place. First time I did this I had no clue about this car, and was not a member of this forum, so I had no idea how to buy/find this new pipe, especially since local dealer knows less than me

Threads merged. Nice pics n stuff. Thks

You're welcome, thanks for merging!

[ChrisFuture8]

In the picture where the white temperature sensor is shown, can someday confirm whether or not they can contribute to the warm air down in the footwell areas that many of us are having problems with? What are those sensors used for...? Do they feed information to the HVAC about ambient temperature. I know on the HVAC control module, there's a slotted area where I think a temperature sensor is located but I'm not quite sure. Anyways, still chasing the mystery of the footwell hot air problem.

Chris

[TxGR8White]

In the picture where the white temperature sensor is shown, can someday confirm whether or not they can contribute to the warm air down in the footwell areas that many of us are having problems with? What are those sensors used for...? Do they feed information to the HVAC about ambient temperature. I know on the HVAC control module, there's a slotted area where I think a temperature sensor is located but I'm not quite sure. Anyways, still chasing the mystery of the footwell hot air problem.

Chris

Heat in the footwell:

• failed heater valve
• unclipped linkage on the stepper motors controlling the flaps
• IHKA controller on the blink
• HVAC Control panel in the center console failed.

If you have access to some spare parts for "testing" it is easy to determine - just swap out one part at a time. For the stepper motors, you will need to look behind the center console bezel to see how they move, and if they actually shut the various flaps in the mixing box. You can verify that by switching between heat and A/C and seeing if the flaps move. They should also move when you change the setting from DEFROST to AUTO to MANUAL SELECTION. If they don't move with each corresponding selection, I would look at the IHKA controller.

[ChrisFuture8]

Well, I currently have the center console apart as part of having the MID unit repaired. It's on its way back so it's a pretty fast turn around. The after picture does look promising.

The heater valve is brand new along with the auxiliary pump. I'm only getting warm/hot air in the footwell and not at the upper torso level vents.

I did buy a spare HVAC module from a member in this forum and swapping it in didn't change anything. I will check out the "IHKA controller on the blink" as you suggested, Gr8White, but I'm not quite sure where that is. I have to search for a picture of that device and its location.

I appreciate your suggestion thus far.

Thanks,

Chris

[Major Cheese]

Duje, nice play-by-play.

Take out the upper and lover glovebox

What if your upper glovebox is an airbag?

[TxGR8White]

Well, I currently have the center console apart as part of having the MID unit repaired. It's on its way back so it's a pretty fast turn around. The after picture does look promising.

The heater valve is brand new along with the auxiliary pump. I'm only getting warm/hot air in the footwell and not at the upper torso level vents.

I did buy a spare HVAC module from a member in this forum and swapping it in didn't change anything. I will check out the "IHKA controller on the blink" as you suggested, Gr8White, but I'm not quite sure where that is. I have to search for a picture of that device and its location.

I appreciate your suggestion thus far.

Thanks,

Chris

CHris,
The IHKA controller is a flat module that slides in behind the heater core box, and is accessed from the passenger footwell. You will have to remove the leather surround and the black plastic under-dash panel above the passenger footwell. Once those are out of the way, you should see some colored connectors (I believe Blue and Yellow) that are going into the IHKA controller. The controller itself is secured with a screw (you will see it once you get up under there. It slides out by presing the black tab on the face of the module to release it from the frame.

[ChrisFuture8]

Thanks, Gr8White. I think I know what you're talking about now. I manage to find a website link to a repair procedure for an E32/E34 and probably can be crossed over to E31.

I need to disassemble a few things to check out the linkage to the stepper motors as well as the IHKA unit.

I am posting the link here, and start a new thread to advertise about that link to members who are also chasing this problem.

http://bmwe32.masscom.net/johan/ihka/ihka.html

Cheers,

Chris

[Hobz]

I'm hands deep in this whole operation and I have noticed that I'm lacking this passengers side dash support as well.

I'm wondering if it is related to whether a passenger side airbag is installed or not, since neither of us has it, but I think txgr8white does. It certainly would make sense to add support to the dash if the extra weight of an airbag was going to be there, not to mention when it goes off and someone's head hits it.

Anyway, I'm ecstatic that I don't have to deal with it.

[nyguy34]

This should be in the archives

[lloydsss]

appreciate this post. i was just going to search the archives because of a new "slight sweet wift of antifreeze" in the morning. is there a quick link to pixs and info to remove that center console?

[cer54467]

Well once again as a true collector i find the sweet/not so sweet, smell of antifreeze in the cabin. Although ever so slight, it is none the less prevalent. This is the 4th car that i am going to have to do this to. Hopefully it will make it to next winter as i just got it out for spring, the snow is not gone here yet.

[Hobz]

This job is not trivial. After doing it the way Duje suggested I can say it is still not easy to get the heater cover and core parts out from the hole in the console. A particular pain are the little clips around the cover on the left side, both of which are pretty obscured. I actually ended up taking the instrument cluster out to get another access point to the top left clip. The left clip popped itself off when I manhandled the cover. The clip lengthened a little and I had to bend it back into the correct shape.

After all that work, this was the only evidence of a leak I could find. The car had been sitting for a while, so the coolant would have evaporated, but I was expecting more than this. Hope all my work makes a difference....



Getting the new core on can be tricky, especially putting on the flange for the left hardline, which, unlike the other two flanges, only has one screw, and has the other side of the flange clamp onto core by rotating it clockwise. Rotating the flange to engage the clamp is difficult, and I resorted to holding the flange with needle nose vicegrips (so that it wouldn't slip off and damage the heater core) to get more leverage.



Luckily getting the clips on again is fairly simple, except the one on the left, which required a very long and slender needle nose pliers to get it in the right place, and a dextrous finger to blindly clip it in place.

I'm still in the process of bolting the interior back together (should have been more organized with my fasteners in hindsight).

All in all, I have probably spent 12 hours on this, and have a couple more to go, so I haven't saved all that much time, and have probably ended up with more cursing. I don't have room in my garage to take the dash out however, so I didn't have any choice.

[cer54467]

Thanx

[Hobz]

Alright, just a reminder to people if you take the cluster out, don't put the key in the ignition with the cluster unplugged :P For some reason I had to put the key in to adjust the steering column out of the way of the cluster to get it out.

I now have the n00b flashing SRS light. Time to go to the dealer.

[84tsport]

thanks for this post duje its the job that scares us the most

[rajah996]

I'll try to explain how to replace heater core without removing the dash

If you have electric steering column, you'll need to unscrew the module that is just on top of the core housing

Does anyone know what module this is and what it does? I have one with three plugs on it (There is a plug in the middle which is white).

Thanks in advance!

[duje]

Does anyone know what module this is and what it does? I have one with three plugs on it (There is a plug in the middle which is white).

Thanks in advance!

Control module for electric adjustment steering column (it is writen in the pic.). Your's is with memory function.