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1961 Cadillac Heater Core Replacement

Started by tractorbll, April 02, 2017, 08:32:50 PM

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tractorbll

Hi.  I am in the process of replacing the heater core in my 1961 Cadillac Series 62.  The car does have air conditioning.  I followed 14.7 in the shop manual but cannot remove the heater assembly.  All five studs and the heater pipes are inside the car, but I just can't break it loose.  It feels like it is hung up on the top side in the middle.  It could be the gasket, but I was pulling like crazy and couldn't dislodge it.  Is there a trick I am missing?  I thought about taking the entire blower assembly under the hood off, but I'm not sure it would buy me anything.

Has anyone ever run into this?  Thanks!

dadscad

I don't know if your car has the same blower duct assembly as the 63 but, on the 63 there are two maybe three hidden (hard to see) speed nuts holding the inside heater duct box to the inside firewall. The interior heater duct studs protrude through the firewall and I think they are located below the blower duct on the engine bay side of the fire wall. It's been years since I did this chore, I don't remember if the blower motor has to be removed or not to access them. If your car has the same duct system, I hope this helps.
Enjoy The Ride,
David Thomas CLC #14765
1963 Coupe deVille

Tom Hoczyk , CLC 14044

I will attach a photo that shows the locations of the studs going through the firewall.  Some are rather hidden and difficult to get to, but you must get them all for the heater assembly to remove from inside the car.  Removing the glove box helps gain visibility.  All the heater ductwork inside the car needs to be removed from the heater assembly.  The assembly needs to be entirely removed to gain access to the core itself.  IMPORTANT:  to remove the heater assembly, you will need to loosen and remove the cables that control the heater valve at the core.  It is crucial that you gain good reference points between the handle positions near the driver, and how far the cables insert into the connectors at the core.  Otherwise your heat control will not be accurate when you reassemble.

I recommend having the heater valve rebuilt while you have the core out.  There is a company in Windsor CT that does a good job of this, forgot the name offhand.  Also, it's a perfect time to replace the control diaphragm that controls the diverter door that sends the air either to the floor for heat, or the mid-section for air conditioning.  The diaphragm itself is visible from the engine side of the firewall, but the screws that hold it are removed from the interior, beneath the dash.  Fair warning:  this job is not for the faint of heart.  If you are not a patient person and are not comfortable for a couple hours on your knees, job it out.   Good luck.
Tom Hoczyk

tractorbll

Thank you all for the help!  I did remove the heater box under the hood and found the sixth stud.  I removed the speed nut and out it came!  The manual mentions 5 studs.  One can make a real difference!  Any input as to the best place to buy a heater core and het the Harrison valve rebuilt?

Thanks again everyone,
Bill

Scot Minesinger

Bill,

Many times those heater cores on Cadillacs fail due to galvanic corrosion, when two dissimilar elements are in contact and water flows thru the copper.  That is why you cannot hang copper pipes with steel hangers.  Anyway, the factory on later Cadillacs solved this problem with a coating on the core.  To me that is not durable.  When I install a replacement heater core, I use the blue Felpro gasket sheets (cutting them) and install between the pot metal or steel and the copper painted heater core.  Then it should last a lot longer.  It makes it fit a little tighter, but it always goes in for me.  You need to be sure there is gasket between every surface or a leak is more likely.

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

Tom Hoczyk , CLC 14044

Fusick Enterprises in Windsor CT did a beautiful job of rebuilding my valve.  Ace Radiator in Fort Wayne IN also did a beautiful job replacing the core.  Unscrew the valve from the header of the core and both pieces can be sent out at the same time.  Ace Radiator 260-484-0441, talk to John, tell him I sent you (Tom HO' zik)
Tom Hoczyk