Heater core repair, day one

Adding an account of my experience to those of others who have repaired Ford Escort heater cores.

Background

• Ford (Mazda?) engineers buried the Escort heater core under the dashboard, making replacement a time- and labor-intensive process
• Engine coolant heated to ~82 C (~180 F) flows through the heater core, warming the air blowing into the cabin
• I paid a mechanic at The Car Czar in Citrus Heights $500 to swap out the heater core in mid-2007...they seemed to do a poor job:
• cracked the dash in multiple places...probably inevitable, but they did not even mention it
• messed up the heater control cables so I have to throw the control really far to the left to get vented air into the cabin
• while taking apart the dash, I think i found a few things which look a bit odd, as well, like a vacuum hose not plugged in near the center console
• Our car overheated at least two times this summer: (1) when the radiator fan died--we noticed boiling coolant exiting the coolant overflow reservoir and ended up towing the car home; and (2) when two fan relays failed during an evening drive to Berkeley--no coolant exiting the overflow reservoir, but very audible noise of boiling coolant in the overflow reservoir
• After these repairs, we noticed our car losing coolant at an alarming rate, re-filling the reservoir every two weeks or so
• A local mechanic diagnosed the problem as a heater core leak and helpfully bypassed the heater core for us
• The mechanic estimated an ~$800 repair bill to replace the heater core: at least five hours of labor plus parts
• Motivation to fix myself: saving money, cold of fall/winter approaching
• This represents the most complicated auto repair I have undertaken

Preparation

• I spent a lot of time reading through the FEOA forums, watching videos, taking notes, figuring out the trickiest parts, asking questions--I did not want to jump in and get stuck
• I annotated RichPin06a's YouTube video as a guide multiple times...took notes, printed them, and used as a guide while in the car
• I started late in the day--not the wisest decision, in retrospect, but I felt impatient to start ; o )
• I initially took Trencher's advice and tried to remove the dash as a whole...then I lost heart as it got late, so I fell back on annotations from RichPin06a's video

Tools used

• Motorcraft heater core (part #HC-8) - ~$50 from Rock Auto (link)
• S & G Upholstery Clip Removal Tool (also known as a panel remover) - O'Reilly Auto Parts (link)
• T20 Torx 3/8" socket (center defroster bezel screw)
• 3/8" universal joint socket (center defroster bezel screw) - AutoZone (link)
• 6" socket extension
• 7mm, 8mm, 10mm, 12mm sockets (assorted bolts)
• 18mm wrench (hood latch release nut)
• 10 mm x 12 mm metric double flex head flare nut wrench (dash bolts under windshield) - AutoZone (link)
• Generic LED work light
• Generic extension cord
• Needle nose pliers
• Box cutter
• Duct tape (tape screws/bolts to pieces they came from)
• Mechanix Wear "The Original" gloves (saves my hands from trauma) - AutoZone (link)
• Generic battery cable puller
• Sharpie permanent marker (mark the HVAC cables)
• Old, thick towel (lay equipment on)
• Zip ties (tie back speedometer cable to battery cage, and so forth)
• Written annotated instructions from RichPin06a's YouTube video
• Tin snips (optional; used to cut one wire ... see below)

Work log

• Worked in my driveway from ~4:00-7:45 p.m., at which time I stopped, on account of darkness
• I decided to tackle the three dash bolts under the defroster bezel as soon as possible, to see whether I had the right tools
• It turns out I did not--the 3/8" universal joint socket I had, combined with the 3/8"-to-1/4" converter socket, plus the 10mm socket, did not fit.
• After a bit of playing, I could see that a 1/4" universal joint socket plus the 10mm socket also would not fit
• I restored the speedometer cable and negative battery cable and drove to a local parts store
• After showing an attendant the location of the bolt, he recommended the 10 mm x 12 mm metric double flex head flare nut wrench...a quick check showed it as a workable, albeit tedious solution
• Total time away from repairs: ~15-20 minutes
• Ran into a snag with the steering wheel shroud cover...missed one of the screws but it all came apart with nothing worse than a few scrapes
• I found the three 10mm dash bolts on each side of the dash tightened too tight and slightly stripped.
• I think I stripped my 10mm socket, so I switched over to a 3/8" socket
• This worked for a few bolts, until I think I stripped that one too... 
• I finally ended up using the next size down SAE socket, which just fit onto the 10mm bolt...that finally worked to loosen the last bolt
• I missed a connector on the passenger side 
• About ten years ago, I swapped out the stock bumper and added a Ford Escort GT bumper, which supports fog lights. 
• As a part of this swap, I investigated the stock GT fog lamp wiring and mirrored the wiring configuration in my LX, running a wire through the passenger sidewall and across to the driver-side fog-light switch
• Unfortunately, I soldered the fog lamp wiring in such a way which prevented me from easily removing the dash
• I simply snipped the wire and will re-solder as part of the second half
• I think one of the driver-side dash bolts may have dropped into the side...cannot remember
• Darkness increases the difficulty of everything...so does sitting in stressful positions
• When I pulled out the HVAC Outlet Duct Extension Center (Motorcraft part #18C505), I saw it had a light layer of coolant - yuck
• The inside of the heater box (HVAC Heater Assembly, Motorcraft part #18478) was coated with white residue--when coolant boils off, it typically produces white smoke
• Pulled out the heater core, sans one outlet tube--I think my mechanic broke it off, which might explain the source of the leak, if it had weakened the outlet tube
• The foam looked a bit gross, but reused it as best as I could on the new heater core
• Reinserted the heater core into the heater box
• Decided this represented a good stopping point
• Dragged all the parts into the garage and locked the rest in the car

Next steps

• If possible, I prefer to replace the stripped dash bolts...probably need special bolts to withstand proper torque...probably something to do later.
• Purchase replacement 10mm and 3/8" sockets
• Fix HVAC heater control cables so they work as intended
• Re-solder cut wire...investigate way to resolder as part of the fog-light switch wiring harness
• Take my time and ensure everything goes back together right
• Probably will take a good part of Monday and Tuesday night
• Investigate why one of the blower motor's contacts in the wiring harness connector seems corroded...something to mention to the mechanic
• Zip-tie under-the-hood light to the hood
• Replace air filter
• Clean seats and carpets

Celebrated with a Ace Pumpkin Cider.