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Subject: Heater Core repair - I. general info Author: davidsoine : member since September, 2004 : 870 posts Posted on: 2004-09-06 14:57:36

Heater core repair - 97 740iL

Here are some tips and info for those interested in repairing leaking heater core O-rings in their late 90s E38. This is not intended to replace the factory service instructions, which are basically correct, but to supplement those instructions. So, step one is print out the factory service instructions required - this will take some time since there are a lot of "references" for this procedure and the sub-procedures.

Parts you will need:

O-rings
64 11 1 468 436 17.12mm One (1) required
64 11 1 468 435 13.98mm Six (6) required

replacement bolt for base of steering column (breakaway head) dealer only, apparently
07 11 9 919 643 M8x30 Fillister-head screw

Large and small tie-wraps for wiring

Cabin (recirculation) filters. Easy to replace during this procedure.


special tools you will need:

If you are even thinking about doing this job yourself you will have most of the tools needed (sockets, every screwdriver in the world including Torx, etc).

The 8mm breakaway-head bolt at the base of the steering column must be extracted/removed by drilling, using an EZout, or grinding the head, etc. This could be accomplished with a drill and a GOOD drillbit alone, I wound up using a combination of drilling/cutting/grinding which leads to a bigger mess.


Procedure Overview:

1. Remove the console
2. Remove the steering column
3. Remove the left support structure
4. Remove the HVAC front cover
5. disconnect heater hoses & blow out lines
6. Remove pipes & replace O-rings
7. reconnect heater hoses, top off coolant, pressure test if possible
8. assemble interior (reverse order)
9. bleed cooling system
10. test drive, check everything, reset radio stations, etc

I estimate this took me 30+ hours, but I went slowly, took some pictures, had to wait for parts, cleaned a bunch of interior parts, bought tools, etc.

At the height of destruction, the project looks like this:


More to come,

best,

Dave

David Soine
97 740iL


Editor's Note: See earlier Heater core replacement message thread

• Heater Core repair - I. general info (pic) - davidsoine 2004-09-06 14:57:36 (15135 views)
  • More followup info (url) - DavidC 2005-04-09 02:43:33 (1230 views)
  • you are one brave man. good work. (nt) - LA-Sean 2004-09-07 01:59:26 (759 views)
    • Indeed, the photos are very graphic. Serious surgery. (nt) - islandbeef 2004-09-07 14:19:00 (883 views)
  • Phenomenal!! Thanks! What was your symptoms that lead to the heater core? (nt) - silber98 2004-09-06 22:31:13 (1073 views)
    • Symptom: Coolant smell when the heat cycled on, esp. Defrost (m) - davidsoine 2004-09-07 10:08:39 (1140 views)
  • Re: Heater Core repair - II. Removing the console (pic) - davidsoine 2004-09-06 19:22:13 (3062 views)
    • Re: Heater Core repair - III. Removing the steering column (pic) - davidsoine 2004-09-06 20:00:05 (2069 views)
      • Re: Heater Core repair - IV. Removing the 'left support' (pic) - davidsoine 2004-09-06 20:14:43 (1761 views)
        • Re: Heater Core repair - V. HVAC cover, heater hoses & pipes (pic) - davidsoine 2004-09-06 20:30:44 (2367 views)
          • Bravo! This is a perfect example of how to document a project - DavidC 2004-09-06 21:49:02 (859 views)
            • The leaking joints were... (m) - davidsoine 2004-09-07 10:18:02 (1011 views)
          • Re: Heater Core repair - VI. Re-assembly (pic) - davidsoine 2004-09-06 20:46:54 (2147 views)
            • Absolutely Beautiful, Well done - thanks!! (nt) - WTH 2004-09-06 21:04:46 (682 views)
              • My goodness, very impressive! - M.Wong 2004-09-07 00:29:23 (670 views)
  • This is great information David. - farnarkler 2004-09-06 18:56:45 (594 views)