HT4100 4.1, 4.5, 4.9 Discussion, Heater Core Removal 83 Eldorado in Cadillac Engine Discussion; My heater core is bypassed and empty. I started this big project to replace it. I got the entire upper ...
My heater core is bypassed and empty. I started this big project to replace it. I got the entire upper and lower dash taken out and can now see the heater core but I'm stumped, even with the fsm to get it out. Right now inside the car I see it is behind a door that swings open and shut with a spring. Under the hood I was able to find just one bolt holding it in. (There aren't any hoses going to it.) What is holding it in? Can someone tell me the next step. My friend told me that at the the factory when they built the car the started with a heater core and built the Eldorado around it. That seems about right.
Your friend is right - it is really buried in there. I just did one over the past two days - and the service manual is pathetic in describing this process. Here are some things I learned the hard way:
The four nuts under the hood are actually there. There is the obvious one you found, there are two more that appear to be holding the A/C housing down on the left (toward driver) side of that housing, but they also hold in the heater core box. The fourth is inside the A/C housing, remove the sensor thing with the wires on it, and look down in the A/C housing for the fourth nut. There is an additional bolt inside the car on the bottom of the heater box.
Remove as much stuff as you can under the dash - ECC, radio, glovebox, etc etc, but you do not have to remove the main dashboard - just most of the modules on the center and right side of the dashboard.
The defroster tubes can not be removed as it says in the manual. Just loosen them and that will be enough. Once the heater box is loose, it will still seem to be stuck on - it is sort of stuck to all the insulation rubber on the firewall. Give it a good tug, rotate downward and out.
This repair is not for the faint of heart - it's a real bitch!
Hope this helps....
I should say - mine is a 1981 eldorado.
And don't forget to carefully remove the controller onm the right side of the heater box and all its wires and tubes and a controller rod before removing the heater box...