View Full Version : 1998 deVille Heater Core Replacement

07-11-13, 08:44 PM
I had to replace my heater core this week. Symptoms: sweet smell and wet floorboard on the passenger side. I looked on this site and found '97 easy to do 98 SXS major job 20+ hours. So for those who need to do this let me tell you it took me under 3 hours including the drive to AutoZ* for the part.
This is my first post so I will try to add pictures also.
First, according to the manual, disable the SIR system
Fuse panel in trunk behind back seat driver's side
Connection to left of steering column

Remove glove box
and unplug second SIR connector

Then remove bottom insulator panel and disconnect battery.
HVAC programer can be pulled out of it's plastic cradle and then the top and bottom air door actuators must be removed
Then just two screws and you have the heater core uncovered.
Sorry can't attach anymore pictures. But you should be able to get it from here. The hardest part is the hose connections in the engine bay. My core failed at the inlet nipple. The plastic nipple cracked. The replacement is all aluminum.
Hope this helps someone. I know I have been helped many times.

Did the Head Gaskets with help from this forum-$1500 and 5 weeks (I'm not real fast and parts/tools had to be ordered).
Love my '98:)

07-11-13, 08:54 PM
No difference between '97 and '98 Devilles. '97 and '98 Sevilles, on the other hand, went from removing just the glove box, to removing both front seats, center console, and the entire dashboard.

07-29-14, 06:18 PM
I know this is an old post but I was wondering if I could gain access to the a/c lines/hoses the same way as you described? I used a dye that showed I had a leak coming from down in that area. To my understanding, people are saying that I need to actually remove the engine itself and that is just not an option for me. There is no freon in my car now and I tried sealants before. There is still a leak no matter what I try. Its HOT in Texas and after I get other things fixed, I really need to work on this a/c somehow. Any an all suggestions would be appreciated! Oh and if I may add, I am also having electrical issues that I think I figured out, terrible oil leak that has left a big mess on the pan and other things, quite possibly a coolant leak, and possibly a leak in the break line that is on the drivers side on top of the engine. Have you had any problems like this as well and if so, what did you do to fix them? Sorry so much but I am in a big bind right now and I need help bad.