Cadillac & LaSalle Club Discussion Forum

Cadillac & LaSalle Club Forums => Technical / Authenticity => Topic started by: Scot Minesinger on January 31, 2015, 12:31:36 AM

Title: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: Scot Minesinger on January 31, 2015, 12:31:36 AM
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
Title: Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
Post by: Coupe Deville 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 
Title: Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
Post by: "Cadillac Kid" Greg Surfas 15364 on January 31, 2015, 09:51:46 AM
Sounds like that Eldo will keep you busy for a while.
Greg Surfas
Title: Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
Post by: Scot Minesinger 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.
Title: Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
Post by: "Cadillac Kid" Greg Surfas 15364 on January 31, 2015, 01:41:12 PM
I repeat my post above.
Greg Surfas
Title: Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
Post by: Jeff Rosansky CLC #28373 on January 31, 2015, 03:41:51 PM
That second picture looks like you will have a real nice personal vent there......
Title: Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
Post by: "Cadillac Kid" Greg Surfas 15364 on January 31, 2015, 04:49:52 PM
Jeff,
I believe that was the "Sahara Desert" option available for 1972 "export" cars.
Greg Surfas
Title: Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
Post by: The Tassie Devil(le) on January 31, 2015, 05:36:24 PM
Quote from: Scot Minesinger on January 31, 2015, 10:53:38 AM
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?
Title: Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
Post by: Scot Minesinger 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
Title: Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
Post by: The Tassie Devil(le) 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
Title: Re: 1972 Cadillac Eldorado replacing heater core-cannot get defrost duct off
Post by: "Cadillac Kid" Greg Surfas 15364 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
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: Scot Minesinger on February 01, 2015, 12:54:29 AM
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.
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: Jeff Rosansky CLC #28373 on February 01, 2015, 09:41:36 PM
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
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: Scot Minesinger on February 01, 2015, 11:50:20 PM
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
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: dochawk on August 19, 2015, 11:21:48 PM
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
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: "Cadillac Kid" Greg Surfas 15364 on August 19, 2015, 11:35:50 PM
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
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: TJ Hopland on August 19, 2015, 11:57:06 PM
Quote from: dochawk on August 19, 2015, 11:21:48 PM
'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.   
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: Scot Minesinger on August 20, 2015, 08:10:37 AM
Yes, there is no way that the heater core had anything to do with overheating.
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: "Cadillac Kid" Greg Surfas 15364 on August 20, 2015, 11:26:57 AM
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
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: Scot Minesinger on August 20, 2015, 10:06:52 PM
I mean you can by-pass it like TJ Hopland wrote.
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: TJ Hopland on August 20, 2015, 11:00:14 PM
If this era Eldo core leaks where does it come out?  Carpet inside or does it end up going out the condensate drain outside? 
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: "Cadillac Kid" Greg Surfas 15364 on August 21, 2015, 12:04:51 AM
Depends where the core has failed.  Usually inside, but the case can direct the water outside as well. Often the core will begin leaking on the body of the core, and what you get is a "fog" out of the vents.  First thought is "wow, that AC is sure cold", followed by the coolant smell that is hard to ignore.
Greg Surfas
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: Scot Minesinger on August 21, 2015, 07:58:39 PM
The 1972 heater core change out was a picnic compared to an 82 Cadillac RWD.  Thanks for sharing the 16 hour time requirement on the 72 heater core change out Greg, now I don't feel so bad on how long it took me.  Granted I'm sure my second 1972 Caddy heater core change out would go quicker. 

The coolant smell came on the 1982 Cadillac and so I'm replacing the original core right now.  The entire dash comes out, disconnect speedo and all.  The easiest heater cores to change are 65-68 Cadillacs.  The 1969 and 70 are under hood too but some in passenger compartment work.
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: dochawk on August 21, 2015, 09:37:55 PM
Since I found the title (still not transferred to me!) to the one in my garage last night, I guess I'll pass on this second one and get this one fixed up . . .

thanks to all for helping avoid a disaster

hawk
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: mgbeda on August 24, 2015, 02:31:06 PM
Scot-

You mean the heater core was that bad on an '82 DeVille or Fleetwood?  I'm surprised because I had replaced one on a '91 Brougham and it was the easiest ever- just had to take off an access panel in the cowl area.  I had assumed that stuff like that was pretty similar from '77 to '92, because the dashboards look the same, but I guess that was a bad assumption.  I wonder what year they started putting that access panel there.  That'd be good to know if I ever was looking for another Brougham.

-mB
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: Scot Minesinger on August 24, 2015, 07:11:13 PM
Yes, 1982 Cadillac RWD, it is the worst ever on any car I have ever seen to replace heater core.  I would think the 4.1 would be enough to limit collectors, underpowered and undependable, just like a 1978 Ford Pinto.  No joke my friend in high school had a brand new 1978 Ford Pinto and it caught fire one day driving 35 mph when it was less than a year old and totaled itself.
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: "Cadillac Kid" Greg Surfas 15364 on August 24, 2015, 09:26:27 PM
In regards to the level of difficulty, practice seems to make these tasks less traumatic.
The non sequiter about the Pinto is poorly chosen. pintos used to catch fire when struck from the rear.
Early 70s Cadillacs were known to be prone to "cooking off" After being driven and then parked.
None of this really has any relevance to the topic.
Greg Surfas
Title: Re: 1972 Cadillac Eldorado replacing heater core-Success got defrost duct & core out
Post by: Scot Minesinger on August 25, 2015, 08:01:46 AM
Hey I was wrong about the 1982 Cadillac heater core removal process.  The RWD car heater core removal is from under hood, and the front drive require the complete dash removal.

The 1978 Pinto caught fire when it was six months old driving forward at 35 mph for no reason - my friend was in the car when it happened.  I know they also caught fire when struck from the rear.  Since the car was destroyed, no one knows how it started.