Anyone good with locks?

Newish (to me) 1996 Defender 90, 300Tdi. Passenger door lock was working perfectly until, one night, it wouldn't latch closed. Just bounced open again, no matter how hard you slammed it. There is a semicircular latching piece visible in the lock edge, and this should be knocked over by the door striker and latch into place, holding the door closed until you press the button or pull the handle. That's what it does on the driver's door; on the pass door it won't lock into place and allows the door to open again.

Took the door card off, gave everything a good wash in WD-40, wiggled all the connectors, made sure nothing was obviously wrong. Lo and behold, it worked again! I opened and closed the door several times to be sure - felt normal. In the morning, I put the door card and winder, handles etc back in place and ... b@gger me sideways it had stopped working again. It's now held closed by bungees until this run of 12-hr shifts is over. As it *can* be made to work properly, I am assuming the issue is wear or adjustment rather than something broken.

I'm happy to fix anything (and usually successful) if I know how it's meant to work in the first place. But door locks always baffle me. Can anyone give me a step-by-step guide to how to check it over and get it working again?

Lock first open, then closed (but won't stay this way):

How easy does the catch "flip" over, try using a large screwdriver/ rod, push it against the catch drives and passengers and check the difference.

I always find the door catch, on the door frame is worn when this starts , the nylon bush is normally worn to a frazzle and I change the whole catch, they cost about £3.

Cheers

this exact thing happened to one of my front doors and in the end I just replaced the latch. MWC1476 (RHS) and MWC1477 (LHS), about £20-£25 each and easy to fit!

neilly said:

How easy does the catch "flip" over, try using a large screwdriver/ rod, push it against the catch drives and passengers and check the difference.

I always find the door catch, on the door frame is worn when this starts , the nylon bush is normally worn to a frazzle and I change the whole catch, they cost about £3.

Cheers

Click to expand...

The catch moves quite easily, but against firm spring pressure. Sometimes it will latch into the correct position, but is easily nudged open again. Other times it won't stay closed at all. Then the other night it closed correctly and stayed closed against me hanging off the handle! The striker has a nylon bush which is worn but OK. I don't think this is the cause, as the problem is there if I use a screwdriver to open it as you say. I'm guessing the fault is in the lock itself, something not snapping into position as reliably as it should. Thanks for the suggestion.

mojo247 said:

this exact thing happened to one of my front doors and in the end I just replaced the latch. MWC1476 (RHS) and MWC1477 (LHS), about £20-£25 each and easy to fit!

Click to expand...

I'm starting to think this might be the best solution. I have never been good with door locks, and the thought of fitting a new one seems much easier. It looks OK to fit once the mounting panel inside the door is removed. Is there any adjustment, or do I just attach the rods with the clips as they were before. Part numbers very helpful, thank you. (Second thought: is it easy to change the lock cylinder so I can use the same key as the RHS lock?)

No need to change the lock cylinders, just unclip the rods and then have lots of fun trying to get them back on again

mojo247 said:

No need to change the lock cylinders, just unclip the rods and then have lots of fun trying to get them back on again

Click to expand...

I want to change them, if it is straightforward, so I don't need to carry an extra key. If it's a massive ache in the nuts, I won't bother. I am expecting to have fun with the actuating rods. I replaced the lock in the tailgate of a RRC once, and I don't want to do that again for a hundred years. Cheers

It is dead easy. I spent ages messing around trying to get the original lock working before I bit the bullet. Unclip the rods, unscrew the 3 screws, and then the same going back on. Long nose pliers help with the clips

mojo247 said:

It is dead easy. I spent ages messing around trying to get the original lock working before I bit the bullet. Unclip the rods, unscrew the 3 screws, and then the same going back on. Long nose pliers help with the clips

Click to expand...

I have plenty of those, and the right Torx bits for the lock. Thanks for the reassurance! Will order tonight.

BlackDogZulu said:

I have plenty of those, and the right Torx bits for the lock. Thanks for the reassurance! Will order tonight.

Click to expand...

wedge window up for when you remove panel and unbolt window regulator

Noted, thanks. Have ordered from a firm called Total Parts (http://www.totalparts.co.uk/) which had the best price of £26.09 incl VAT delivered. Genuine would have been around £85 ... great, but no thanks. I'm off all next week, so should have it sorted then. Thanks to all for the advice and suggestions.

dont fit an allmakes latch i fitted 3 in a row all failed then bought a genuine one

Don't think I have ever used Allmakes. This one is a Bearmach part. I've always found them OK.

FYI mine did the same thing was caused by a slightly bent door though not the actual lock. If doesn't work have a look at that

It's counterintuitive, but I had a failure-to-latch problem which was much improved by replacing the plastic guide that the lock button goes up and down in. Either the door would fail to latch when slammed or it would appear to be secure and then I'd discover that the door was open as I was driving along. It would then be impossible to close, which was awkward when I was in motion in heavy traffic. The part in question was the plastic guide which screws to the door frame (not the escutcheon which goes through the door trim panel). New one in, and everything works perfectly. I even bought a new lock mechanism but I've never needed to fit it and it's still in a box in the shed.

alexc2701 said:

FYI mine did the same thing was caused by a slightly bent door though not the actual lock. If doesn't work have a look at that

Click to expand...

I had the exact same problem.

alexc2701 said:

FYI mine did the same thing was caused by a slightly bent door though not the actual lock. If doesn't work have a look at that

Click to expand...

Landyfox said:

I had the exact same problem.

Click to expand...

I'll bear this in mind, thanks. The door seems straight and the panel gaps are correct (for Solihull values of correct), but who knows?

Brown said:

It's counterintuitive, but I had a failure-to-latch problem which was much improved by replacing the plastic guide that the lock button goes up and down in. Either the door would fail to latch when slammed or it would appear to be secure and then I'd discover that the door was open as I was driving along. It would then be impossible to close, which was awkward when I was in motion in heavy traffic. The part in question was the plastic guide which screws to the door frame (not the escutcheon which goes through the door trim panel). New one in, and everything works perfectly. I even bought a new lock mechanism but I've never needed to fit it and it's still in a box in the shed.

Click to expand...

I've had the door card off and examined the lock and handle rods as they are working, and they seem to be free enough. (I had a similar issue with the remote locking system on a P38, solved by a tiny spritz of WD-40 on the passenger lock escutcheon plate - slight friction there was stopping the whole system from locking.) However, I will have a closer look at that, and maybe I will have no need for the new lock either.

BTW, ignore my questions about the lock cylinder above. I thought the cylinder was part of the main lock, but it seems it isn't.

I changed the drivers side front latch yesterday with a new one, took 20 minutes, dead simple!!

Saint.V8 said:

I changed the drivers side front latch yesterday with a new one, took 20 minutes, dead simple!!

Click to expand...

Good to hear!

BlackDogZulu said:

I'll bear this in mind, thanks. The door seems straight and the panel gaps are correct (for Solihull values of correct), but who knows?

I've had the door card off and examined the lock and handle rods as they are working, and they seem to be free enough. (I had a similar issue with the remote locking system on a P38, solved by a tiny spritz of WD-40 on the passenger lock escutcheon plate - slight friction there was stopping the whole system from locking.) However, I will have a closer look at that, and maybe I will have no need for the new lock either.

BTW, ignore my questions about the lock cylinder above. I thought the cylinder was part of the main lock, but it seems it isn't.

Click to expand...

Mine didn't look bent till I took the seals off and you could see the diffirence in the gap. Block of wood at top and a couple of slams and it worked fine

Well, that was a bear of a job It didn't help that I had to work in a steady drizzle, and it took way longer than 20 minutes! New lock is now fitted and working. Haynes was a good guide, but had a few errors, or at least the pics and text referred to different doors from mine. I totally failed to do the most useful thing, which would have been to take lots of photos before unclipping all of the rods and levers. But I didn't need to open up the driver's side to compare - it is all logical and although it needs the hands of an infant in places, it all went together fine and is now working again.

Thanks to everyone for the help and advice.