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Author Topic: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out  (Read 6747 times)

Offline Scot Minesinger

  • Posts: 6004
1972 Eldorado replacing heater core.  The upper dash pad is off, the glove box lining is out, and the "T" duct divider is out.  The single screw in figure 1-13 of shop manual that shows the defrost duct is out too.  It reads in the shop manual to "remove the defrost duct from under clips"- I don't see how it comes undone.  Has anyone else replaced a heater core and had to remove this defrost duct from clips?  Please help me.

Thanks,

Scot
« Last Edit: February 01, 2015, 12:49:52 AM by Scot Minesinger »
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Offline Coupe Deville

  • Posts: 652
  • Name: Gavin William Myers
Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
« Reply #1 on: January 31, 2015, 09:18:38 AM »
Hello Scot. I am trying to remember when I did the heater core on my 72'. It was a real pain. If I remember correctly on my car I just twisted them back and forth and they slid off. And there was that rectangular black rubber duct that went from the heater box to the front dash vent that was hard to install/reinstall.
Sorry I am not much help.

-Gavin 
-Gavin Myers CLC Member #27431
"The 59' Cadillac says more about America than a whole trunk full of history books, It was the American Dream"

Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
« Reply #2 on: January 31, 2015, 09:51:46 AM »
Sounds like that Eldo will keep you busy for a while.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline Scot Minesinger

  • Posts: 6004
Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
« Reply #3 on: January 31, 2015, 10:53:38 AM »
Yes, here is the Eldo deconstructed.  Will be making another attempt at the defrost duct this afternoon, any helpful advice would be appreciated. 

BTW these sound techs that go into a dash to modify/replace a radio should be publically flogged sometimes.  The clock was never reconnected and neither was the sensor tube.  Not to mention missing screws, incorrect fasteners and etc.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
« Reply #4 on: January 31, 2015, 01:41:12 PM »
I repeat my post above.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline Jeff Rose CLC #28373

  • Posts: 2324
  • CLC Number: 28373
  • Name: Jeff Rose
Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
« Reply #5 on: January 31, 2015, 03:41:51 PM »
That second picture looks like you will have a real nice personal vent there......
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
« Reply #6 on: January 31, 2015, 04:49:52 PM »
Jeff,
I believe that was the "Sahara Desert" option available for 1972 "export" cars.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline The Tassie Devil(le)

  • Administrator
  • Posts: 12388
  • CLC Number: 18992
  • Name: Bruce Reynolds
Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
« Reply #7 on: January 31, 2015, 05:36:24 PM »
BTW these sound techs that go into a dash to modify/replace a radio should be publically flogged sometimes.  The clock was never reconnected and neither was the sensor tube.  Not to mention missing screws, incorrect fasteners and etc.
I know how you feel.   The dash fascia in my own '72 was butchered that much that I had to replace it completely when I re-fitted a replacement radio after getting the car home.

And the wiring was just as bad.   Luckily I had all the necessary parts from the '71 I stripped at the time I exported the car that made repairing everything a lot easier.

Comparing the '71 with the '72 has shown me that there are a vast differences between the two, in every place on the car.   Doesn't look much, but parts simply can't be replaced without changing other stuff to compensate.

Bruce. >:D

PS.   Even my detailed pictures of the behind the dash can't assist in advising you what to do regarding the duct.   When I stripped the '71 back in 2008, I removed everything without the thought of putting it back into the same car.   Just kept everything for the new car.   Would it help if I dug it out and had a look at the back of it?
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Offline Scot Minesinger

  • Posts: 6004
Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
« Reply #8 on: January 31, 2015, 05:49:02 PM »
Bruce,

Thanks for offering.  If it is a lot of trouble do not bother digging out older data.  If do find that battery hold down, would be super interested in it.  If you have a picture of the defrost discharge duct/nozzle out of the car, the back of it at top by windshield picture would be helpful.

All,

Had to remove the duct pointing at driver to remove speedo cable from back of speed, as somehow the plastic parts were shredded by previous people working on the car (never seen anything like it), and the speed does not work.

Thanks,

Scot
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Offline The Tassie Devil(le)

  • Administrator
  • Posts: 12388
  • CLC Number: 18992
  • Name: Bruce Reynolds
Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
« Reply #9 on: January 31, 2015, 07:36:02 PM »
I will get them out of their hiding place tomorrow, as I need assistance to get that far into the pile of stuff.

It is up in there somewhere.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
« Reply #10 on: January 31, 2015, 09:42:43 PM »
I see it Bruce.  It is in the second picture beside the thing-a-ma-bob, rite behind the do-hickey.  Seriously Bruce, Easy does it.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline Scot Minesinger

  • Posts: 6004
Heater core is out of the car. 

There are two tabs on each side of the defrost duct (four total).  The tabs are about 1/2" x 1/16" metal and extend down about 1/2".  The plastic defrost has slots that go around theses tabs and lock it in place (not up down), just side to side and front to back.  The heater core underneath holds it from going up and down.  I guess during assembly the factory assembly works found that the defrost duct falls out in advance of the heater core installation unless you twist those tabs with a set of pliers.  This is of course contrary to shop manual.  Once I discovered this and twisted them back the defrost duct was able to be removed, and shortly thereafter the core too.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Offline Jeff Rose CLC #28373

  • Posts: 2324
  • CLC Number: 28373
  • Name: Jeff Rose
Where are you getting the new ductwork?  Mine is kind of tired so I have had to use the Hi Speed, Cadillac quality, Duct Repair trick (duct tape).
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Offline Scot Minesinger

  • Posts: 6004
Jeff,

That ductwork is in good shape and does not need to be replaced - amazingly.  It is in that position so I could disconnect speedo cable, as it was bad and has to be sent off and re-built.  No sense putting it back until rebuilt cable arrives and installed.  This dash is messed otherwise, vacuum lines cut, plastic tabs that anchor dash to metal body are busted, missing brackets, missing braces, wiring disconnected and cut.  Should be able to straighten it out though.  With heater core out there is more room.  All butchered for the sake of a radio and the installer of it saving a half hour. 

Anyway I have purchased duct from USA parts.  Trouble is you have to go there because they have all these sizes and they do not really know what goes to what car.  I'm driving to USA Parts on March 7th.  If you mail me a small section of duct you want matched and tell me the length you need I can get you a replacement.  Snip of a one inch donut ribbon sample of the duct and send it to me. 

Hope your Caddy is driving well.

BTW, black duct tape is probably a fairly durable repair.

Scot
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Offline dochawk

  • Posts: 627
  • Name: Richard Hawkins
I stumbled across this while searching.  I'm looking at buying (another) '72 convertible, and the seller indicates a mechanic believes the overheating is from a heater core that needs replacement.

How long does this repair take?  Does the console need to come out?

My regular mechanic couldn't find entries older than 1980 in the book, which said 6 hours.

Is this something that a reasonably adept person can fix?  Does the console need to come out?

thanks
1972 Eldorado convertible,  1997 Eldorado ETC (now awaiting parts swap from '95 donor), 1993 Fleetwood but no 1926 (yet)

Richard,
The factory service manual clearly and explicitly  describes the step-by-step removal and replacement of the heater core.  The first one I did on my 72 Eldo took me a total of 16 hours, but then it was my car and I tried to do everything precisely as instructed.  If you are going to do this yourself a factory service manual is mandatory, and it would be a good idea to have one for future use as well.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline TJ Hopland

  • Posts: 10183
'72 convertible, and the seller indicates a mechanic believes the overheating is from a heater core that needs replacement.

My regular mechanic couldn't find entries older than 1980 in the book, which said 6 hours.

I don't believe that the heater core would cause overheating.  Many of the 'hot rod' guys that use these engines just block the heater outlet in the engine and don't have issues so lack of flow there should not hurt anything.   If the core is leaking and someone did something to the system like modified the radiator cap to prevent it from building pressure and the cooling system was in generally poor condition along with the rest of the car I could maybe see it boiling over after shut down on a warm day due to lack of pressure.   Unless this car is priced really really cheap I would investigate this overheating issue a lot closer.   

If the core is leaking you can just loop the hose to bypass it and get the system to build pressure again to see how things go.   I think one hose is a 5/8 and the other is a 3/4 so you will need an adapter but that should not be hard to find.  I think I read that you can get a PEX fitting that will do that for cheap at lowes or home depot if you can't find one at an auto parts store.  I think I would be taking an IR temp gun with me next time I went to look at it and probe around under the hood to see what the temps are doing.

The 79-85 is a significantly different car on the outside than a 71-78 so I would suspect they are also different when it comes to accessing the heater core.  I own both but luckily have not had to do a heater core on either one so far.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Offline Scot Minesinger

  • Posts: 6004
Yes, there is no way that the heater core had anything to do with overheating.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Yes Scott there is.  Often the first signs of a blown heater core is the engine overheating due to the loss of coolant.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Offline Scot Minesinger

  • Posts: 6004
I mean you can by-pass it like TJ Hopland wrote.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

 

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