Hi everyone.

I have an issue with both of my doors where:
-door won't latch when swung shut if unlocked, but when locked it will
-doors can be locked but not unlocked from the lock cylinder (even with new cylinders)

The truck is an 1985 f350 460 C6 4WD single cab. Locks fully manual.

I haven't been able to find literally any other posts about this issue on any forum, unless the locks were electronic / had an actuator to fail. Any thoughts on how to fix this would be appreciated. Thanks!

 

Look at the strike pin (on the door jambs) is the plastic bushing around the pin still there? I t is very common for the plastic bushing to wear out and fall out which then makes the door not close and latch fully (but lock-unlock would not change that).


Your problem is odd, if it where one door only, I would think the latch itself went bad, but both doors - it is unlikely both latches went bad.

 

I agree, when you slam the door and it won't quite shut all the way and requires several tries to make it latch, I have replaced the plastic around the post thing on the door jamb on the cab, and it fixed it. What I have done is cut a short piece of PEX plastic plumbing tubing, slit it down the side, and snapped it over the post. Works well and lasts surprisingly a long time. I believe you can also get the plastic piece from Dorman HELP!.

You also need to look at the doors as they shut. It's very hard to detect, but see if the door is being lifted up as it shuts and runs over the pin sticking out. If it's being lifted, your door hinges are worn little bit. If you do not feel like going to the trouble to replace the door hinge bushings, you can put some washers behind the lower door hinge where it mounts to the door to kick the rear of the door up so it does not have to ride up to receive the cab latch pin.

 

First if the pin bushing are bad they should be replaced.
Now if you are going to loosen the bolts for the washers why not loosen the other bolts to the body and adjust the door up?


Now to the issue at hand.
It is not going to be an easy fix but "I think" you need to pull both latch assy. for a good cleaning and lube. I don't see anyway to get them clean when in place let alone lubed good.
Dave ----

 

Hi Folks - thanks for the quick feedback. I was able to go put some time in on the truck last night, without much luck.

Something I did find while playing with/cleaning/lubricating the lock assembly- the lock cylinder was actually actuating the bar and linkage for operating the latch, but the last 15% or so of travel requires an incredible amount of force- more than a key can apply before breaking - i saw this happening when actuating the latch/unlock using the internal door handle. I found no defects in the bars or linkage that would cause the binding - perhaps something in the latch itself? Is this a tell-tale sign of anything to anyone? It makes an audible snap/pop noise when it finally overcomes that last bit of travel.

Additionally, when the door is locked, the latch jaws seem to operate normally, but when unlocked it is very lose and spins fairly freely. Is this a tell-tale sign of something wrong, broken?

@CountryBumkin:
Neither door has a bushing around the metal strike pin, and I see no evidence that there was any there before. I have included a picture of the latch and pin for reference. Is this supposed to be thicker?

When I bought the truck in January, the passenger door was like this. The driver door just started doing this a few weeks ago. When purchased, the driver door would latch when unlocked, but sometimes took a few attempts. It locked manually when you pushed down the pin, and when you pulled the interior handle, but would not unlock from the lock cylinder. Now they both behave the same.






@Franklin2:
originally this is how the door functioned, but not anymore. It latches easily when the door is locked. So while I think the pin might be able to use the plastic shroud, i don't think its causing the latch to not function. Thanks for the PEX trick, i may give that a go.

The door is being pushed up- the pins are bad, and I have new ones to install, but again, i'm not sure this is the issue causing the locking situation.

@FuzzFace2:
pins/doors are slated for being done already, but as noted in the above responses, i'm not sure this is the main source of the issue.

Any thoughts on how to get the assembly all the way out without ruining it? The screws were OK and came out, but the joints where the bars attached to latches and tabs (plastic inserts) seemed very brittle and frail. I didn't have a ton of time, and definitely not time to run to the parts store when working on this earlier, so I decided against attempting to remove them.

Thanks!

 

First I must say I had the glass out of my doors as I felt it was easier for other work I had to do to the doors like replace all the glass guides and inside/outside sweeps.


With the glass, regulators, etc. out it gave me more room to sneak the lock assy. with the rods still connected to the lock assy.


Why I pulled it with the rod still hooked up was because I could not undo them plastic rod holders.
Once out I let them sit in my parts cleaner for a day before I hit them with a brush and worked them to make sure all was good.


If you do break any of the clips I think you can get them at any auto parts store.
Dave ----

 

Have you drowned the latch in wd40 to see if that helps? May save you from taking it out.

 

Yes, there should be a plastic sleeve or bushing around the striker pin.