Ambulance Door Lock Behavior Question

[RWBeringer4x4]

Hey all -

Very minor step forward today as I finally got enough penetrating oil into the ambulance door lock to get it rotating. It locks and unlocks, but not as I would expect, so I'm just wondering what is considered normal.

Before anyone asks, I haven't pulled the latch assembly apart because almost every screw is very obviously stripped by the PO:

So I'll try to explain what I'm seeing:

Then interior lock moves when I insert the key outside and turn it left or right. However, with the key anything other than vertical, the key becomes jammed in the lock. I can't remove it:

As an example: door locked, key jammed:

If I return the key to center (vertical)

The door unlocks, but the key becomes free.

Also, the cylinder appears to be loose in the door, as evidenced by it pulling out slightly when trying to remove the jammed key:

Now here is what's weird. I've found that if I insert the key (vertical) then twist it to the right, the door locks. Twisting back to vertical to then release the key, the door remains locked and I can remove the key. So, in this manner, I can lock the doors.

To UNLOCK the door, I must turn the key LEFT from vertical, which unlocks the door, then return the key to center in order to remove the key.

However, once I have turned the key to the LEFT and unlocked the door, I must then turn the key all the way to the right, then back to center, then right A SECOND TIME in order to re-lock the door and free up the key. The pattern is like this:

1. Turn key from center to left, then back to center: UNLOCK

2. Turn key from center to right, then back to center: STILL UNLOCKED

3. Turn key from center to right AGAIN, then back to center - door locks.

Under no circumstances does turning the key to the left lock the door.

I'm guessing this is slightly abnormal...and probably due to a slipped cam-device on the other side of the cylinder, but since it does work, in an odd way, I wanted to make sure this wasn't normal before I got out a drill and drilled out all the stripped screws to replace the lock.

The good news is, it looks like OEM locks are available, so if needed I can grab one when I place my next parts order with Beno. Any thoughts?

To recap:
1. Is this locking behavior normal?
2. Do I need a new lock?

 

[78fj40mg]

Rick, That's how mine locks and unlocks as well, I'd say it's normal. Try using some WD40 in the cylinder to loosen dirt and rust and it should be fine. Also from your last picture the cylinder appears to be loose, there's a C clip inside to hold it in place yours might be broken.

 

[Curt]

I bet the lock tumbler may be installed incorrectly, if you can remove those stripped screws try and re assemble it yourself. It is really easy to do so and you can make sure it locks properly before assembling again.

 

[RWBeringer4x4]

Rick, That's how mine locks and unlocks as well, I'd say it's normal. Try using some WD40 in the cylinder to loosen dirt and rust and it should be fine. Also from your last picture the cylinder appears to be loose, there's a C clip inside to hold it in place yours might be broken.

That's about the weirdest locking mechanism I've ever heard of...But I know Toyota did all sorts of wonky stuff to try and keep you from locking your keys in the car...

I bet the lock tumbler may be installed incorrectly, if you can remove those stripped screws try and re assemble it yourself. It is really easy to do so and you can make sure it locks properly before assembling again.

Yeah, ultimately these doors will get the full treatment, so drilling out the screws is an inevitability. I'll probably be leaving well enough alone in the short term because

1. I'm just glad I can get them to lock now - I haven't been able to in the 3 years since I've had it
2. It'll be way easier to drill them out while the doors are off the truck.

 

[honk]

I bet the lock tumbler may be installed incorrectly, if you can remove those stripped screws try and re assemble it yourself. It is really easy to do so and you can make sure it locks properly before assembling again.

Curt's right. My key goes in topside down, cut edge up and turns counterclockwise to lock, clockwise to unlock. The key returns to vertical, uncut edge downward, and is inserted and withdrawn from that vertical position.

 

[RWBeringer4x4]

Curt's right. My key goes in topside down, cut edge up and turns counterclockwise to lock, clockwise to unlock. The key returns to vertical, uncut edge downward, and is inserted and withdrawn from that vertical position.

Interesting...my key goes in "teeth up" which I think is how yours does it, but I can't get it to turn a full 180 degrees to "teeth down" in either direction.

 

[firestopper]

My 82 ambu door lock is the same. Turn to the left (90º) then back to center will lock the mechanism, turn to the right (90º) then center to unlock. The key will not come out if not back to center in either lock/unlock position. I would get some graphite spay in the tumbler after cleaning with WD and compressed air. My key is "teeth up" as well.

 

[Curt]

The lock can be assembled a couple ways, only one way works. When i installed my new tumbler the first time i put it in i had this problem, when you take it apart you will see how. The new lock key like firestopper goes in teeth up, turn left 90* back to center key pulls out and its locked. Turn key 90* to the right and back to center and is unlocked again key pulls out

 

[RWBeringer4x4]

My 82 ambu door lock is the same. Turn to the left (90º) then back to center will lock the mechanism, turn to the right (90º) then center to unlock. The key will not come out if not back to center in either lock/unlock position. I would get some graphite spay in the tumbler after cleaning with WD and compressed air. My key is "teeth up" as well.

So I guess this is sort of normal, BUT, do yours have to go right twice after unlocking? It's like the cam on the tumbler doesn't push the lock quite far enough the first time or something

 

[Curt]

from the inside the lock should move smooth. does yours? maybe it has been over tightened as well. The key going left and right only does 180* never full rotation.

 

[RWBeringer4x4]

The lock can be assembled a couple ways, only one way works. When i installed my new tumbler the first time i put it in i had this problem, when you take it apart you will see how. The new lock key like firestopper goes in teeth up, turn left 90* back to center key pulls out and its locked. Turn key 90* to the right and back to center and is unlocked again key pulls out

Ok - sound about right only mine is left (counterclockwise) to unlock, right (clockwise) to lock. Maybe it's installed 180 degrees off? I'd think if that was true though, the key would go in teeth down.

I'm wondering if the fact that the cylinder is loose is causing the cam to "miss" the locking mechanism occasionally, which might be why it takes a couple of attempts to get the lock to move.

from the inside the lock should move smooth. does yours? maybe it has been over tightened as well. The key going left and right only does 180* never full rotation.

Ok, it sounds like mine is installed correctly if it can only move 180 from left to right. The inside lock moves very smoothly. Ps, there is a hole at the end of the lock "shaft" that look like it might have been a pin to hold a handle pin on or something. Did the inner lock on these trucks have a thumb crank or something?

I know I'm missing the rubber/plastic handle cover on the inside. I'm thinking there might have been a plastic lock handle too.

 

[honk]

from the inside the lock should move smooth. does yours? maybe it has been over tightened as well. The key going left and right only does 180* never full rotation.

Curt, if I may: the key will turn a total of 180* total - 90* counterclockwise to lock, 90* clockwise to unlock; both from the key teeth up insertion.

Further up, in post #5 I should have said "teeth up" instead of "cut edge up"...sorry if confusing.

Am I right to think that it's normal that the key itself can be inserted into the lock either way, teeth up or teeth down, but will only work the lock if inserted teeth up in a correctly installed lock mechanism?

 

[Curt]

I did it a while ago but i remember the mechanism was in several pieces that could be assembled in a few ways, any markets with a left locking door?

I may have picked that orientation because of the little swinging cover.

 

[Tex40]

I don't have my hardtop on right now but I recall that I had to turn the key to the right, then put some pressure on the door handle which in turn put pressure on the cam and hold it in place while I returned the key vertical to remove it - doing that would lock - if I didn't put pressure on the handle the cam would rotate back with the key and remain unlocked. Might try that if it makes sense.

**Oops, I said right, but it may have been turn left to lock.**

 

[4Cruisers]

On a side note: IIRC, the entire mechanism (handle, lock, etc.) is the same on my '76 FJ40 ambulance door as the passenger door mechanism on my '71 FJ40. Has anyone else noticed this? Or am I going senile before I can even start getting Social Security?

 

[RWBeringer4x4]

I don't have my hardtop on right now but I recall that I had to turn the key to the right, then put some pressure on the door handle which in turn put pressure on the cam and hold it in place while I returned the key vertical to remove it - doing that would lock - if I didn't put pressure on the handle the cam would rotate back with the key and remain unlocked. Might try that if it makes sense.

Haha yep - ok good sounds like it's working as it should!

 

[micdon]

What happens on the inside of the door when you lock/unlock the door? How big is the play on the inside door handle? At least it looks like the visible parts are installed correctly.

This how mine is installed anyway and it works exactly like honk says

I have more pics in build thread Rolling rebuild and dumb questions

 

[RWBeringer4x4]

What happens on the inside of the door when you lock/unlock the door? How big is the play on the inside door handle? At least it looks like the visible parts are installed correctly.

This how mine is installed anyway and it works exactly like honk says

I have more pics in build thread Rolling rebuild and dumb questions

Yeah, looks like mine. As I mentioned I haven't been inside the mechanism because the PO stripped all the screws on the latch assembly. There is a significant amount of play in the lock cylinder and the door latch. My guess is that I have it assembled correctly, the play in the system is just making it a little stubborn.

If I do what Tex mentioned above, and push down on the latch while returning the key to center, it seems to hold the locking cam in place.

In short - I think everything is setup like it should, just kind of a quirky mechanism.

 

[wscbill]

Regarding the back door lock, page 5 of the 1976 User's Manual says:

To lock and unlock the right door from the outside,
turn the key counterclockwise to lock and clockwise to unlock.
The key cannot be removed unless you turn it back to the center position.

 

[Weber Sarge]

Should work the same as the late-70's door looks , as Bill detailed from the manual ...
Sarge