Door Latch Refuses To Unlock

Hey guys, on my buddies 85 Caprice 4 door sedan, The passenger's side door will not unlock. It can't be opened because of this. We've tried slim jimming it, we managed to somehow get the door panel off, and everything is connected to the latch unit that I can see, and everything seems to be in working order... The lock goes up, it goes down, the key works fine, but no matter what position the lock is in, the dorr will not open. I'm stumped. I cant take the latch off for further diagnosis and/or repair until the door is opened. I've even tried to unbolt the striker bolt, but that did no good. Any help to get this thing open would greatly be appreciated. Thanks in advance!

Front or back door?

Have you tried pushing inward on the door before depressing the latch button to relieve pressure on the latch cam? I've had a few unibodies that are weak and sagging bind the latches in that manner. Granted, it's on a frame, but there could still be some body twist.

tell him to be like bo duke and get in through the window

Front door. And yeah, we tried that. Tried that in combination with everything else too.

Since no one mentioned this yet soak the crap out of the latch assembly with your favorite penetrating oil, let it sit a while and try opening it. If that doesn't work, have some one push on the door from the inside while lifting the handle from the outside. I has a situation like this happen with an 81 malibu wagon it was a broken door hinge pin causing the door to sag which bound up the latch.

Is there resistance or any feel when you try the door release? I'm not entirely familiar with the vehicle, but isn't there a rod from the handle(s) to the latch. Also, what happens when you work the door lock?

This sounds like it may be a bit of a bit** to resolve. Can the interior door panel be removed?

I've tried WD-40, lithium grease, and motor oil. I dont think a lack of libricant is the problem as I've maintained lubricant in all the latches, locks and hinges since I've owned the car. The lock seems to work fine, except it doesnt do its job, it moves freely, and we did manage to get the interior door panel off with a lot of manhandling. I can see the latch and lock assembly. ALL the mechanisms move freely, everything seems to be connected. There is a rod coming down from the door to the latch assembly and it is connected as well. There is hardly any resistance when trying to pull the door handle (exactly how it feels when the lock is engaged on any other door) It sucks because this is the second most used door in the car.

is the car rusted? it could just be wedged into place and just needs to be kicked open (last resort).

When you lock and unlock the door, can you see anything happening on the latch? It sounds like the latch is jammed. I don't know what it looks like, but is there anyway to poke around with the innards (probe or something)? Sounds like you need a little luck to get something to move to release the latch. I'd try poking around with anything with a helper bumping on the outside and working the release. With any luck, you can get the sucker open. Maybe get a replacement latch and see how it operates, it may give you a clue as to how to get it released.

I sure hope someone has a better idea for you, that really sucks.

coat-hanger maybe?

SUCCESS! I tried re-soaking it with about a whole can of WD-40, let it sit for a while then did it again, Then i took a small ballpine hammer and gave the latch a continuous hard tap from the inside of the door, while lifting the lock up and down repeatedly. The I put the lock to the unlock position, and pulled the handle and "pop" it came right open. We then took the latch assebmly out and took it apart and there was a lever loaded with rust. After a little grinding, and covering with LTG (long term grease) we got it to work like new. Thanks for the help guys!

Good Job! If I were you I'd WD-40 the rest of them, you shouldn't have to pull the panels. let them soak for a few minutes then Grease them up with an all purpose lube to keep it from happening again.

If you read the factory service manual, the proper lubricant for hinge pins, latches, and hood/deck hinges is 20W oil. Spray oils are generally too thin, don't cling, and tend to wash away any useful lubricant. Grease may work, but doesn't do well in cold climates.

Glad you got 'er open! Funny how door latches are something most people never have to worry about.

I've got the opposite problem on my '64 Chevelle, the door won't shut well.

My father's 89 Sierra has the same problem with the passenger door, doesn't shut too well. I guess its a common thing in older vehicles (latch problems).