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1984 Eldorado
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42 Posts
Discussion Starter · #1 ·
Hello to all. I have an '84 Eldorado in very good shape and the parking brake decided to not release. I can release it manually with the lever located under the dash, right in the path of the returning foot pedal. Obviously this will allow me to drive but is not the way to operate the parking brake. Very painful if not careful. I know it operates on a vacuum but how? I looked underneath and can see the command device on the steering column which goes to what looks like the actuator on the brake assembly but not sure what is not working. I checked the hoses and they all seem to be there but checking the vacuum in that location will not be easy. In addition, the brake quit releasing after I had parked on a rather steep incline. I could hear it creaking backwards as I stood next to the car but didn't think much of it at the time. Could this cause a reverse vacuum and cause a hose to pop off? Any tips or advise on how to trouble shoot would be welcome.
 

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Super Moderator
2010 DTS
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89,123 Posts
You're on the right track. You have a vacuum leak.

The parking brake release is on the same vacuum circuit as the HVAC so you may have air defaulted to the defrost mode as well.

Most common cause is a ruptured vacuum diaphragm on the parking brake mechanism. If that is good and holds a vacuum, trace the vacuum line back to the programmer. If all the lines are intact, you have a vacuum leak before it gets to the cabin. Check for vacuum at the cabin supply line on the passengers side firewall. If no vacuum there, the vacuum pump may be suspect.

 

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1985 Seville
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326 Posts
There's a rubber vacum manifold with 2 holes in it on top of the steering column you can't really see it from the floor you have to feel for it check and see if that came off. Mine became disconnected and my brake wouldn't release.

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If you find it and it's connected disconnect it you can feel a vacum pull there if you have vacum in the cabin.
 

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1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
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6,738 Posts
Very easy to diagnose, buy/ borrow a MityVac vacuum tool. Pull the hose off the vacuum pot at the parking brake assembly. Attach the MityVac with a hose long enough to test this while sitting in the seat. Set the parking brake. Now pump the MityVac. After maybe 3 pumps it should release the parking brake. if it doesn't release, that confirms a failed release pot (diaphragm) If it does release then the vacuum hose to it is leaking or the supply to it is disconnected, pinched. That "command" device simply allows vacuum from one hose to transfer to the other hose when the shift lever is moved from park. My other concern is the fact that you say the car creeped backwards. A lot of Eldo's of this era suffered from infrequent use of the parking brake. Not used the pistons seize in the bore of the rear calipers. Once seized, the caliper pistons wont grip the rotor with enough force to hold the car. Most people, for some reason, put the car in park THEN they set the parking brake. The parking brake should be applied and held down as you shift to park. That way the weight of the car rests on the brakes rather than the little parking pin within the transmission. Its worse on an incline because it might cause binding of the shift linkage and make it very hard to get out of park. Seized calipers rarely can be repaired by a layman in his garage. Best to buy rebuilt calipers.
 

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1984 Eldorado
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77 Posts
Hello to All,
I'm having some problems with the parking brake releasing. In this thread, you can see the auto-release feature quit working so I secured a release cord on the manual lever. This has worked for several years, but now I'm experiencing a parking brake which does not engage. I'm hoping it only needs some lubrication, which will be the starting point. If not, I have just scavenged a junk yard parking brake assembly off a 1985 Biarritz. I'm hoping the 1984 base coupe and 1985 Biarritz models are compatible. I had the part removed by a guy at the junk yard and watched the process. Three bolts and a cable. However, he trashed everything that was in the way. It looked like a fuse box and other stuff. If I need to change this part out, I will need to be substantially less destructive. Has anyone ever done this? If so, are there any precautions or tips to share? From my perspective, it looks like the assembly was installed prior to all the rest, so it's not an easy unbolt and re-bolt. Any input would be appreciated. Thanks, Big Bird
 

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141 Posts
Folks
Having 2 1981 Eldorados that had/have parking brake lever issues maybe some of my grief will help!
As I completely restored the rear brakes, testing the calipers, cables, adjustments etc everything rear of the adjustment bracket (outside under the driver seat) was in top condition.. But I had 2 issues with the parking brake lever under the dash. First I took many photos with a digital camera.
1.One car had the lever depressing very tightly but wouldn't stay engaged. I found a small broken spring that normally returns the manual release arm (it ratchets acting as a pawl) . A relatively easy fix.
2. # 2 car had parking brake pedal that was almost frozen! After wd40 and a crow bar I managed to get some movement. Enough to set the parking brake with extreme foot pressure...So I too have I toyed with the idea of removing the 3 attachment bolts freeing the parking brake lever assemblyly. My photos show 2 bolts are accessible but the one at the 1 o'clock position is very hidden! But maybe if it's only a frozen/rusted cable that needs replacing then maybe I'll leave the parking brake assembly in place. Does anyone know if the cable is restorable or should I install a new one? Who sells them? I tried RockAuto, but no luck!
 

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1984 Eldorado
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77 Posts
Hi King. Thanks for the input. It looks like you have some challenging issues. Replacing the cable (if you find one) seems daunting without even mentioning the brake lever. I'm going to try some WD40 on the level in the car and hope it's a lubrication issue. I know a junk yard in Georgia that has three Eldorados (83-85) and they can pull parts if you want them to. Although they would have to lift or turn the car over to get the cable. I'm don't know if that would be a showstopper. You probably already know the others. I've had good success with Caddy Daddy. Let me know and I'll post a link if you want. Thanks, Big Bird
 
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