Central locking on W123. Please help!

[Supervillain Dad]

I have just bought a lovely old 280 and I am on the whole very pleased with it. However, In between me inspecting it and the first time I had to put petrol in, the central locking packed up. I got the petrol flap open with a screwdriver, but couldnt get in to the boot with the key (only one came with the car.) After fiddling with the fuses for ages, I realised that the locking was not electrical at all, but worked on a peculiar air pressure system. There is still a tiny bit of life in some parts of the system and I somehow managed to get the boot open and tie the mechanism so that it would stay unlocked. I would like to try to restore the central locking system (Haynes not much help on this one) and also arrange to be able to use a key in the boot, so that I can be sure of getting in to it again when I lock it. Does anyone have any ideas on what might be wrong, and does the ignition key usually fit the boot on these cars?. I would be very grateful to anyone who can enlighten me. I am rather new to this car repair lark.

 

[andy_k]

the ignition key should fit the boot lock, but bear in mind it's 3 position, unlocked manually, locked manually, and lock/unlock with the central locking.

Sounds like you have a vacuum leak somewhere which is why the system isn't working properly, this same leak will also have an adverse effect on the smooth running of the car including gear changing so you need to find out where the leak(s) is/are. It's a bit hit and miss for the DIY mechanic, but check the obvious pipes and unions under the bonnet that you can see first including all the ones to the engine and gearbox, then check all the connections to the accumulator (under the rear parcel shelf).

After that things get a little more complicated as you will need to check the seals on each door lock mechanism - if you are lucky you will hear a slight hissing from the offending unit.

Does the locking work on all the locks when the engine is running? - sometimes the last one to work will be the one with a fault on it so you can isolate the problem pretty quickly. however, it's fair to assume that if the seals on one of the locks are worn then the others will be in need of replacement - they cost very little from the dealers and once you have done one, the rest are a breeze.

HTH

Andy

 

[slkbenzman]

On the Eclass the locking is powered by a vacuume pump under the back seat which is electric with the fuse box being next to it I dont know but yours may be the same

 

[Spike]

Mebbe this will help you sort out the problem :wink:

http://ow.no/mb/w124/tech/electrical/centrallockingsystem.html

 

[andy_k]

I'm not 100% sure on this one spike, but I think the W123 system is different to the W124 one shown in that help file. AFAIK the W124 doesn't have the accumulator set up that the W123 has - well if it has we haven't found ours yet

Andy

 

[jaymanek]

The 123 has no electrics at all, therefore the link wont help im afraid. I have described the 'rebuilding' of the system a few times on this forum, will try and find the thread tommorrow.

The key doesnt work because youve either been given the round one or a copy of it.

Originally the cars came with 2 or 3 Square master keys which fit, doors, ign and boot. The round was a spare that didnt work the boot. Someone asked if the round key could be modified to fit the boot lock, but i think the answer is no.

The soln to that problem is take the V5, a passport and your cheque book to the dealer who will order you a new square key. But try and fix the locking for now to see if that temporarily solves your problem.

In short, leaks usually occur at:
1) the boot lock mechanism, if you look at the thing that moves to lock the boot- attached to two vac pipes - see if the rubber has perished here.
2) There is a similar system for the petrol flap, it is accessed from the boot, remove the plastic lining and youll find it.
3) The major culprit - Above the petrol tank in the boot is where the pressure is stored for the system. It looks like a load of tennis balls stuck together, check for leaks here by running the car and listen for hissing.
4) Divers door has a mechanism. this is too complicated to explain, but quite intuitive after staring at it for 10 minutes! P.s it is supposed to hiss when locking the car, so dont think its a leak.
5) Valves - There is one from the manifold before the vac pipes enter the cabin, its yellow, makesure its ok by removing and sucking on it. (You shouldnt be able to suck through it). There is another white in the footwell on drivers side, somewhere above the accelerator.
6) Other than that its checking all the doors and links.But almost guaranted the main problem will be one of 1-3.

Ok ive now gone on long enough! any more and please do ask- ive done this a few times.

Thanks

Jay

 

[Supervillain Dad]

Thanks everyone for your help on this one. Jaymaneks and Andy K's instructions sound pretty straightforward. Would this problem with the vacuum system problem explain why the gearbox seems to take a moment to realise that I have floored it and change down?. I will give it a go and let you know how I get on. Wish me luck!.

 

[njpumphrey]

The key you have may be a secondary (spare/service) key if it doesn't work in the boot. If it is it will have a round grip, whereas the master key will have a square grip. You CAN make a master key from a secondary as it has the same side-on profile, but has different width grooves running the length of the key. Your local key cutter should have a reference book to do the right one for you. As for fixing the leak in the vacuum system, I am told it is usually the boot lock which goes first. Mine has just started to go, and will need looking at soon. Good luck.