1967 Cadillac EldoradoGERALD´S CADILLACS - NEWS

1966 AC BLOWER VACUUM MASTER SWITCH

Until a few days ago the ATC (Automatic Temperature Control) in my low mileage 66 worked perfectly. All functions were operating as they should.
I rebuilt the carburetor and let the car idle for a while. During this I wanted all accessories to move and also turned on the heat. It came on as always and after about 30sec the blower went off again. The power servo started to move in and out all the time by itself, but the blower would stay off. The idle speed up came on and off as well depending on the placement of the power servo. After a while it stopped doing this and stayed in the fully retracted position (full heat). If I turned the temperature dial it did not change anything - but it was around freezing outside and this is what it should, do as the sensors sense the low temperatures and then send the system into full heating mode.

I checked the following things.

  • Master Switch seemed to work and gets engaged by vacuum. Power is going through it as it should. Current is going in and out. (This is what I thought…)
  • Blower Motor tested with a direct feed - worked.
  • Blower Motor Relay - tested. Put a 12 V feed to the dark blue connector and it engaged and the blower motor came on. There was no current coming through the blue wire though.
  • Power Servo - cleaned all contacts and measured the resistance in all positions  - looked good to me.
  • Control Head in Dash - removed it and checked the blower switches - it seemed to work.
I checked the amplifier part and the big square resistor  was showing the 50 Ohms it should. Also measured the rheostat on the temperature dial, which seemed to work as well.

Full vacuum was applied to the power servo, and I also checked the vacuum and voltage at the transducer. I also checked all vacuum actuators with a vacuum gauge, but everything checked out perfectly.

I then put everything back together. Still the system did not work in the full heat position. I did a lot more tests and checked the vacuum and electrical diagrams.
I ordered the 1966 AC manual from "Cadillac Tim" which is available also on ebay for $45,- . These instructions are a must-have for your car, as everything about the AC system is explained very well by Tim. There is a great troubleshooting guide in there. Its money well spent! Tim also offers a rebuild service for many Cadillac parts and has a great selection of refurbished parts. Check out his website!
1966 Cadillac Dash Control Unit

The 1966 dash control unit - here you can see the amplifier part.

After days of troubleshooting it finally dawned on me where the problem was. I had checked the master vacuum switch multiple times and when checked it always had electrical continuity. But I did not check it correctly. I only pushed the backside of the switch until I heard a click.
I should have tested it with full vacuum applied. As it turned out, if high vacuum was applied to the switch (during heating mode), the switch did no longer work correctly!

masterswitch-IMG_8114The contacts did no longer touch when full vacuum was applied to the switch…

Today I took it apart and made a video about it. As it turned out the switch contacts did not align as they should and I had to bend it a little bit to make it work again. I then put everything back together and now the AC system works perfectly again. Check out the video for all the details!

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1978 ACCELERATOR PUMP REPAIR

My low mileage 1978 Eldorado Biarritz ran super nice. It idled like a clockwork but it sometimes had one problem:
The car would have a slight hesitation for one or two seconds when driving away from standing still and idling. The hesitation was not present at any higher speeds - only when starting from standing still, no matter how hard I hit the pedal.
Once the car was rolling, it ran perfectly. 2 or 3 times the engine even stalled in the past.
That's why I suspected the accelerator pump.
Replacing it is not too difficult. You basically only need a rebuild kit and remove the carburetor from the car. Then you have to remove 8 screws to take the top off and remove 2 linkages. I'm not a carburetor expert at all, but luckily my friends, who did the job before, helped me. I found some great how-to videos on YouTube which show how the Quadrajets are taken apart and back together - Quadrajetpower.com has some very informative videos on its youtube channel - here is one of them. I also bought rebuild kits from them:

1978 Cadillac Carburetor QuadrajetThe Quadrajet after removal.78carbopen-IMG_8059
The Quadrajet with the top removed
accpump-IMG_8058bgThe accelerator pump on the right sidecarbmonday2guys
My friends Steve and Lucky helped a lot. Thanks my friends! We did all the work in Luckys fantastic garage and shop.
carbmondaysteve+gerald
friendsandcarbsWe had "Carburetor Monday" as everybody was working on their carburetors.

We replaced the pump rubber and put everything back together. The carburetor looked very clean inside with only minor deposits, so we left everything else as it was.
I can't wait to install it back into the car and hope the problem is fixed - did not do a full rebuild as it is still very clean and nice inside. Only installed new rubber on the pump and new top gaskets. Hopefully the problem is fixed now. I will update the page once the carb is back in the car.

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1966 HOT CHOKE CARBURETOR REPAIR

When I got my 1966 Cadillac back the choke did no longer work. The hot air choke mechanism on the Carter AFB carb was stuck open and thats why the previous owner removed the choke linkage, which would close the primaries when the car was cold.
I removed the choke housing from the car and it was completely stuck and did not move at all. Both the lever and the counter weight were completely frozen up although everything inside the housing looked pretty clean.

First I tried anti seize oil which did not change anything. Then I soaked the unit in a parts cleaner solution over night which did not free it up either. The next day I soaked it in a rust removing solution which did not help either. I then put it in a can of transmission fluid for a while.
In-between I always gently tried to move it and suddenly it freed up and now works perfectly smooth again. I put the carburetor back together and now the car is very easy to start again - even on a very cold day.


The choke after repair.
chokeassembly-IMG_8035The choke mechanism disassembled for repair after I managed to free it up.chokeassembly-IMG_8028IMG_8037

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1967 ELDORADO CARBURETOR REPLACEMENT

I installed a rebuilt carburetor from www.carburetorcenter.com into my 1967 Eldorado today. It suffered from bad idle when fully warmed up at low RPM. It had a problem with the secondaries not closing properly and was worn out a bit. It's an easy install. The 1967 Eldorado uses a unique linkage for the transmission switch, which is a one year only item. Take good care of yours!
The Eldorado now purrs like a kitten again with its new Quadrajet. I now have two more carburetors to do - the 1966 has a stuck choke and the 1978 needs a new accelerator pump.... The video is also available on YouTube in 4K HDR quality...


I took a short video of the installation process.1967 Cadillac Eldorado Quadrajet
The rebuilt Quadrajet on the bench.
Original 1967 Cadillac Eldorado Quadrajet
The old original 1967 Eldorado Quadrajet - this is the non California version.

1967 Cadillac Eldorado Quadrajet

The rebuilt Quadrajet installed.

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