I think it's finally time to do the heater core - question

[Jeff N.]

Tired of the smell of antifreeze in the car. Have had the pipes and o-rings for years but have really just not wanted to do the job.

Question of those who have done the job - what is the likelihood that my heater core is actually bad vs just the input pipes and o-rings?

[Robin-535im]

Tired of the smell of antifreeze in the car. Have had the pipes and o-rings for years but have really just not wanted to do the job.

Question of those who have done the job - what is the likelihood that my heater core is actually bad vs just the input pipes and o-rings?

Hi Jeff,

I can only comment on my own past two experiences... both times I've done it, it sure looked like it was just the o-rings, but I didn't take the time to pressure test the core. I just figured a new one would be worth putting in just in case since I had the whole thing apart. I have never done the tubes, just the core itself + new o-rings. The tubes looked like a whole new level of effort; the core alone was work enough!

Hope all is well up your way - and that you have a good Holiday/Solstice/Etc or whatever you're allowed to call it these days :)

- Robin

[Tiger]

Have you used a cooling pressure tester and test your system for any visible leaks? I did mine not too long ago and found lots of leaks by the radiators... all hoses that I replaced with the radiator.

External leaks smell is easily drawn into the car from hood. Which brings me to another topic... hood seal does fail and doesn't seal properly due to age... so you are breathing engine air.

[Jeff N.]

Thanks Robin. Do you recall how many duckets a new core was? I agree it's prudent to stuff a new one in if you're in there. How much time should I allocate for the job? (And how many ibuprofin's for my back?)

Tiger - good thought. I haven't done the pressure test but I'm pretty much 100% sure it's the pipes/core. When under the car, you can see the antifreeze residuals by the header drains in the tranny hump. And all the other hoses in the engine bay are new within the last 2 years.

[Jehu]

I paid about $140 shipped for a Behr unit and finished over two days in a total of about 8 hrs fist time doing it. If I'd have started at about 10 am instead of 12 pm I'd have finished but I ran out of light and I used the existing aluminum pipes ,didn't need to replace them nor did I test my system or the core specifically for leaks . The Only snag I had was fitting a wrench on the nut that secures the clasp plate which fits over the two side pipes at the core. That piece swings down over the pipes and is bolted into the core body. The Metal dash Support bar was in such a position it was difficult even with a swivel adapter to fit a socket on and I lacked a small enough open ended wrench whcih may have worked better. Fitting the socket and tigheting that single bolt sufficiently took me an hour alone. I might suggest inspecting the stepper motors while the area is open ..

[Bill R.]

Stefan Borch's page from a few years back? He came up with a method on the e32 to remove the heater core without removing the entire dash and made the process considerably shorter... Pretty close to the same on the e34

His site is no longer around but you can pull it up here on the wayback machine...http://web.archive.org/web/20070902171924/www.homeofsbc.com/Fixes/Heater/heater.htm

[Jeff N.]

Ah - I do remember that page. I think it scared me off from doing this job for so long. Dashboard work = ewwww in my book.

Ever personally done the short process? Looks like you can replace the pipes and o-rings but not the core? Hard to tell to be sure. I suspect my problem is the pipes but of course won't know until I get in there.

:)



Stefan Borch's page from a few years back? He came up with a method on the e32 to remove the heater core without removing the entire dash and made the process considerably shorter... Pretty close to the same on the e34

His site is no longer around but you can pull it up here on the wayback machine...http://web.archive.org/web/20070902171924/www.homeofsbc.com/Fixes/Heater/heater.htm

[shogun]

Stefan probably made the first online info available. And of course as the first one he made some 'mistakes', or better to say some unneccesary work.
I can only speak from the E32. There is no need to take the dash out. Just the center console, the OBC, radio, covers under the dash, the glovebox and the big angled pipe support on passenger side LHD side. And it also helps to take out the steering wheel and the front seats, then you have much more space. We did that last year on an E32 750iL Highline from 12/1992.
Actually I was only 'assisting' my buddy with passing on tools and making memos what goes where. better to make pics. Not much space for 2 people there, but it helps to have someone around you. Here pics
http://www.bimmerboard.com/forums/posts/427855/

http://www.bimmerboard.com/forums/posts/454565/
This also might help from a japanese DIY
http://dd.jpn.org/BMW_HP/20081201/index.shtml

In case the car does not have aircon, that is done in 30 minutes
http://www.7-forum.com/forum/24/waermetauscher-ausbau-735i-bj-9-88-a-48616.html

[shogun]

and one more copied:

heater core replacement DIY
didn't document with photos but in case anyone wants to tackle the heater core replacement, here are some instructions. Perhaps it will be good for the archives at any rate. I, of course imply no guarrantees of success and take no responsibility for your peril (I'm not a lawyer). But seriously, it's not too hard.
Tools: Philips #1 and #2. Socket or wrench 8 or 9mm and 13mm. Small straight blade screwdriver for prying. Flashlight.

1. Pry off vertical black strips to right and left of center black console housing the radio, etc to reveal screws.
2. Pry off wood dashboard strips below instruments to reveal screws.
3. Remove drivers lower dash panel via 6 screws
4. Open/lower glovebox (can keep attached by straps).
5. Remove shifter knob, leather boot surround, wood surround (reach hand in and pop up forward edge, slide forward and up (towards ash tray) to clear tabs at edge of wood closest to you).
6. Remove rubber and foam around shifter rod.
7. Pry off color-coded cap from screw at junction of front and rear consoles (where center recess is between arm rests).
8. Unscrew said screw.
9. Pry off leather parking brake surround and lift up a little.
10. Unscrew screw at bottom of opening around parking brake which holds down driver's side of front console to rear console.
11. Pry off rear black panel where rear airducts are located.
12. Use 8 or 9mm socket to unscew two side bolts holding rear console in place (I couldn't easily budge the 2 phillips screws but this is an alternate).
13. With rear console free, slide it back 5 inches but don't need to lift up.
14. Using 8-9 mm socket, unscrew black plastic bolt holding rear of front console in place on a ridged plastic tab.
15. Up front, unscrew single phillips screw holding small carpet piece along right and left sides of transmission tunnel (e.g. near accelerator pedal) and slide piece of carpet forward and lift off.
16. Unscrew black phillips screw holding front bottom of center console to a brass metal tab on both sides.
17. Unscrew any of the four remaining screws at black plastic console holding radio, climate control, etc., revealed in step #1
18. Attempt to free the front center console. The window switches need to be pried up and disconnected along with the hazard switch. I don't have ASC but this switch, if present, should be disconnected. Un plug white connector holding wires to cigarette lighter.
19. Try to swing upper center black console containing radio to the right. As you do so, disconnect radio wires, climate control cables, and climate control wires. Look at how connectors come off carefully; one has a small lever that needs to be pulled which helps eject it. I didn't disconnect the computer but this could also be done.
20. Swing this assembly to the right and balance on open door of glove box (don't scratch your wood - use a protective paper, cloth, etc.
21. Revealed is now a big black plastic enclosure to the heater core. Disconnect temperature wires at white connectors on each side.
22. Unscrew two phillips screws at front base of enclosure.
23. Un-bolt two shock absorbing mounts at base of front enclosure.
24. Remove 10 clips holding enclosure back (facing you) to the front half. The clips at driver's side may be tough to spot and access due to the obvious wires and metal support rod, but this is "do-able".
25. Clip tie wraps holding t-shaped wire loom in front of enclosure and push this and climate control cables up, out of your way.
26. Remove enclosure panel. Start at passenger side and pull towards you, then slide to passenger side and free driver's (left side) from behind wiring etc.
27. Now you see heater core!
28. Un-screw each of three pipes slowly and make sure paper towels are on hand. I didn't drain coolant and did lose 1/4 cup from top of core and pipes, but that's all. Make sure towels soak up any draining coolant and not your carpeting.
29. carefully bend/move passenger element pipe torwards you to make room for removing core (just a little).
30. Core is only held in place by the three pipes. Pull top of core forward torwards you and lift out of dashboard.
31. Clean plastic box well.
32. Have three new washers on hand for attaching new core and pipes.
33. Test the new core to rule out leakage by reattaching the climate control and running the car.
34. Assembly, is, well reverse of above.
35. Bleed the coolant system.
I hope I haven't missed anything. Good luck.

Using these instructions, and putting everything into its own numbered plastic bag took me only 2h 15 mins to get to the core, and about the same amount of time to put everything back together.

[Jeff N.]

Thx Erich. Helpful. I think the Japanese site is to remove the aircon core not the heater core but still has good pictures.

I think based on all this, I'm going to order up a heater core and replace the pipes as well. Just seems like cheap insurance relative to the effort.

[Robin-535im]

Thx Erich. Helpful. I think the Japanese site is to remove the aircon core not the heater core but still has good pictures.

I think based on all this, I'm going to order up a heater core and replace the pipes as well. Just seems like cheap insurance relative to the effort.

FWIW it's also a great time to shampoo the carpet under the seats, under the center console and around footwell area. I always seem to find some nice coffee stains when it's all pulled apart.

Beware the white plastic electrical connectors - can be very brittle. The black plastic ones seem to fare better.

[Jeff N.]

Good idea. I actually have an entire replacement carpet in the basement just waiting to go into the car. And a new headliner. And some M5 sport seats (that need a little more love to be ready). Maybe I should just pull the trigger on a bunch of projects.

BTW, anyone sitting on a good, black drivers side seat belt? My belt is getting a little crusty.


FWIW it's also a great time to shampoo the carpet under the seats, under the center console and around footwell area. I always seem to find some nice coffee stains when it's all pulled apart.

Beware the white plastic electrical connectors - can be very brittle. The black plastic ones seem to fare better.