A Different Kind of Ultra

I decided to tackle a different sort of ultramarathon, replacing the heater core on my 1995 Audi 90 Quattro. Normally, I would have taken it to the mechanic and let him have the fun, but the timing of the heater core failing was bad: just 1 week prior I had the timing belt replaced on my 98 Pathfinder. A week later, the heater core went out in my Audi. I knew it was this as I was smelling anti-freeze inside the car and not out, and when I turned on the heat, I got a huge misty cloud of vapor instead. I was going to wait a week and have it done when the wife’s 92 Audi 100 crapped out in town due to a failed fuel pump, I knew I had spent enough money on two cars ($2000) and didn’t want to spend another grand for my car. So I decided to try it myself.

I did a lot of researching on the web (thank god for Google) and found a number of sites with the needed information, but the following link was the best…..and with pics:

http://forums.audiworld.com/showthread.php?p=18463995

Since it was the start of August, I figured I had plenty of time to get it done before winter. It took me a month to get it done, but this was working weekends, with two weekends off (working at the Leadville Bike race, and the following week running Lean Horse 100 in South Dakota).



For the start, it was fairly easy. I started with taking out the center consoles. Then the driver’s side kick panel under the dash, then the glove compartment. In order to remove the driver’s airbag, I had to go into town to get a set of torx screwdrivers, as the horn/airbag is attached with these nuts. Once I had the airbag off, it was fairly easy to get the wheel off. I made a mark on the wheel and the hub in order to align it all up. I then removed the turn signal/cruise control/wipers/headlight switch from the column, and it was easy to take out the instrument cluster. It was then on to the passenger airbag. When I looked at it from underneath, all I saw was one torx bolt and a metal bracket. But I couldn’t figure out how to remove the bracket to get to the airbag. Turns out it was only the torx bolt holding it in. I found this out when I had both side dash bolts off and began to wiggle the dash, and noticed the airbag moved out as well. It slipped right out. The heater controls, CD player, ashtray all came out fairly easy from the center console. The hazard/seat heater/fog lights/rear defroster switches were a bit of a challenge to remove.

I then moved inside the engine compartment to remove the hoses to the heater core and the two bolts holding it onto the firewall. In the process of removing the two hoses, I accidently broke a line to the PCV valve. I’ll have to deal with that later. The lower bolt was tight and a bit tricky, but I got it off, and the hoses along with the gasket. No coolant leaked when I pulled the hoses.









Once the passenger airbag was removed, there were four bolts on a bracket holding the dash in. Once undone, it took some wrestling of the dash to get it removed. The ducting was in place and it took some wrangling to get it off. Once off, there it was, staring at me with all its glory: the heater box. There were clips holding it onto the evaporator housing. The top and bottom clips came off easily, as well as the two front clips. This left two clips from behind. Based on the instructions from above, it was going to take some work to get the bottom one off. I had to go back into town and get a mechanics mirror on a wand. Using this as well as a flashlight, I was able to see the clip that needed removing. It took me the better part of a week to get the clip off. I ended up getting some small etching tools, with various bent tips to get at the clip. I ended up cutting off half of the tool as there was very little room to get at it. I'm not very good at using mirrors for such things, as I have trouble dealing with the reverse image. But it didn't take long to master the technique. What a relief to finally get the lower clip off. All it took now was some back and forth motion of the heater box and the remaining clip let loose.





Now that the box was off, all I had to do was remove the old heater core. There was antifreeze on the top of the floor vent housing just below the heater box, as well as inside the box. After cleaning up inside the box and wiping up all the antifreeze, I was able to put the new core in and screw it in place.



The reassembly of dash parts was fairly easy. I ended up having to undo the dash bolts about 3 times to get stuff to line up right though. The hazard switches were a bitch to replace. Not a lot of room and the switch plugs were hard to get at. Somehow in the process, the hazard switch went inop. I’ll have to take it by the mechanic to fix, as well as the PCV valve that broke.

When I was installing the driver’s kick panel in, I found out I forgot to put some of the wiring harness back in place, as it was preventing me from getting the panel back in properly. I really didn’t want to take out the dash again, so I brute forced the wiring harness back under the dash lip. It wasn’t completely in, but enough to get the panel back on and bolted. The glove compartment was fairly easy. I had to replace the disk changer underneath the glove box, but that went pretty smooth.

I ended up with two leftover bolts (from the kick panel) and two bolts that mated the center console to the lower support bracket. As there were originally four of these mounting bolts, two on each side, I ended up bolting on one bolt each side. I doubt this will present a problem. I was damned if I was going to undo the dash yet again for these two little bolts.

In the end, the car started right up. The only thing not working are the blinkers, which may be related to the faulty hazard switch. I drove it into town to make sure everything was working, and the low coolant idiot light came on. After stopping at the store for antifreeze, the coolant reservoir was nearly empty. So I filled it up, and drove back home. I again checked the reservoir tank level, and it was still full. Must have been from the new heater core getting filled up with coolant.
Well, I saved a lot of coin, but I really don’t want to do that kind of job again, unless I have lots of time on my hands. It was a learning experience to be sure.

But, once is enough. I'm a happy camper.