| SUPPLEMENTAL FAQ -- HEATER CORE REPLACEMENT I recently did the heater core replacement in my ’91 2+2 and thought I’d pass along some additional hints and tips to others. I also wanted to thank YT Nitram (Ty) and Maxdoc (Jim) – had to email both a few times with some questions. Ty’s Heater Core Replace FAQ was a great help -- it can be found at this URL: [ http://www.twinturbo.net/net/viewmsg.aspx?forum=technical&msg_id=723192 ]
Additional tools that are helpful:
- Long (11 inch) needle nosed pliers --- ones with a 45 degree angled nose.
- Exacto knife duct taped to 15 inch wood dowel or other extension
- Zip lock bags (big ones and little ones)
- ¾ inch roll of masking tape and sharpie marker
- Digital camera General I would strongly recommend using a digital camera to take pictures along the way. It really helps later when you can’t remember where a vent part or electrical connector is fastened down. There are many, many parts, screws and fasteners that need to be removed. Your #1 rule – whenever possible is to put all screws and fasteners back into the fittings they came out of. Masking tape is very helpful for attaching some screws and plastic fasteners to removed trim pieces and other parts. This makes remembering where things go a lot easier. Same for plastic bags – group all the screws for the glove box together in a single bag and label it. Use the Sharpie marker to label male and female electrical connectors (D1, D2 – driver’s side parts, P1, P2 – pass. side parts, etc ). Label ducts and other misc parts as well. Getting Ready…. - SMELL IMPORTANT – If Z has the auto climate digital system --- Make sure heater box vents are set OPEN for floor (feet) setting before starting your work. Makes it easier (after heater box is out) to clean off old antifreeze scum once you have it apart. Vents are hard to operate by hand w/out power! - SAFETY -- Remove negative terminal from battery – you don’t want live voltage in your harness and you want to be sure no power is present to any air bag devices. Removing things…
- Remove cowling from around steering column early in process. This is the part that protects the ignition key switch, etc. Just make things easier. - Steering column should only be allowed to drop approx. 2 inches. Just enough to clear the bolts that hold it up. Plan to make a little wood T-brace with some 1x3 or 1x4’s . Wood brace can be fastened to steering column using a wood screw via steering column flange used for plastic trim cowling. Wood brace has total overall length of 16.5 inches (base + vertical brace) works nicely. Note – tried hanging steering column via some wire fastened to metal flanges where dash screws down – but wire got in the way of other work. Wood brace to floor pan placed just under ignition switch area is the way to go. - Be sure to take out dash upper side vents (on top near doors) – they will hang up on vent ducts underneath when you try to pull dash. - Rear electrical connectors on very rear (left side) of gauge cluster requires pressure on both sides (2 fingers) to unlock and remove from connector. At least it’s that way for my ’91. - Easier to remove AC box and Blower Box rear spring clips by locating them with one finger and then using other hand to insert long handled flat blade screwdriver under spring part and twisting. Only issue is that sometimes one of the plastic supports for fasteners will break. I repaired broken ones by epoxying Velcro rough-side patches to each half and then using a Velcro cloth strap to bridge and hold the two box halves together. - As Ty’s FAQ says, heater box will feel as if it is bolted in-place and doesn’t want to come out. A way to make this easier to get free is to remove the engine bay nylon bezel that supports the heater core pipes as they pass thru the firewall.. I tugged on the heater box for a bit and pulled the heater core pipes into dash area maybe 1 inch or so. Then used 11 inch 45 degree needle nosed pliers to work the bezel loose inside engine bay and pull it off the pipes. Made heater box much easier to tip/tug and then remove from cabin. - Be careful where you grab the heater box to pull and tug. Grab the metal brackets and not any of the actuators or control linkages. They are fragile!!! - I used an Exacto knife ducted taped to a 15 inch wood dowel to more easily cut off the old heater hoses attached to the heater core pipes. Made getting into that space very easy.
Cleaning & prepping things…
- IMPORTANT -- Be sure to flush the spongy insulating foamy material on lower (foot) vent flap with clear clean water -- this flap controls the heat flow for your feet. Otherwise you'll continue to have a bit of a Coolant smell in cabin when foot venting is ON. I wish I had done a better job -- should have held this part of core under water facet and let it run for a while. I will need to go over it again in spring, from inside of car with a spray bottle of water (sigh). - Be sure to clean out mold/mildew on A/C box Styrofoam basin, I used some Lysol mildew (w/bleach) cleaner. - Be sure to clean out any bugs/twig in blower box area or on A/C coils. Be careful with A/C coils – do it gently. - Lubricate heater core cams/levers with white grease. Clean them up a bit first, remove lint, dust and hair. Might want to spray brake pedal and clutch linkages too? - Spray Styrofoam lower portion of A/C box with some Silicon lubricant - makes easier to slide back into place over A/C coils. - Rinse out (under tap) or clean with paper towel ALL plastic duct work -mine was filled with lots of dust! - Use a Q-tip with some alcohol to clean off all of the temp sensors in the various ducts. Dirty/dusty sensors don't work as well. Don't forget the sensor on driver's side at end of 1/2 nylon (round) tubing on lower rear foot venting (same vent the has footwell light) - Might want to replace clutch Master Cylinder, easier to get at pedal linkages and adjust clutch pedal with dash removed? I did mine even though it wasn’t yet leaking! DO THIS BEFORE INSERTING HEATER CORE BACK INTO CABIN FITTING… - I'd strongly recommend attaching a ground strap to the metal clamp in rear of heater box that
holds the two heater core pipes. Fasten wire to clamp screw and then ground other end of wire to good body ground. Reduces any issues with "electrolysis" effects in coolant. I used my digital meter to measure heater core DC voltage with and without the strapping grounded. Voltage with car off was nearly 0.5 volts – yikes. It dropped to 0.3 volts with engine idling but ZERO is better. I don’t want any more heater core leaks (at least while I own this car).!, Putting it back together - Check your digital pictures from time to time – you will forget things!!!! - Don't even try to re-install AC Box REAR spring clip nearest to heater box, instead epoxy Velcro hook fasteners on top and bottom AC BOX halves. Once everything is together, use a long piece of Velcro cloth stripping to bridge the two patches . - Spray a little silicon lubricant on a paper towel and rub over various electrical connectors before plugging them back together. Makes it easier to get them apart again if you have to (later). - Once you get it all done – pop your t-tops to re-set them. Car body flexes a bit during repair and t-tops will creak a bit afterwards.
Hope this helps anyone who undertakes this extremely time consuming repair!!!!
|
Supplemental Tips -- Heater Core Replacement - 
