WesleyCole

I bought my first MB....LOVE IT but it does have a few little problems and a trans prob which I will address later.

First and foremost. My key will unlock both doors and trunk from ANY outside key insert location!

Problem is if I lock the car using the button from the INSIDE it will not always lock or unlock.

If key makes vacuum hoses and pumps work, why is it not working from the inside?

Help? Oh i was a shade tree mechanic back when computers didnt exist so please be patient and a bit detailed. Thanks

1989 MB 300CE

WesleyCole

so far this site is useless

Rock

Maybe you would have more luck if you posted in the correct forum.

I moved your thread………... consider it your first useful encounter on MBworld.

WesleyCole

thanks maybe if it came with simple instructions

Saijin_Naib

Does multiple presses of the switch inside trigger the lock/unlock?

If so, then the likely culprit is corrosion on the metal contacts in the switch. Pull the dash wood, pull the switch assembly, and scrape the contacts clean.

stormtigers

Also pay you to have a look at the vacum pump and hoses.
Located under rear RH passenger seat (RH if you facing same direction as the car).
I had intermittent lock/unlock with button issues and found that the hoses on the vacuum pump were stretched and losing pressure.
$5 worth of rubber hosing replaced and no more issue. One of the first things I did to my coupe.
https://mbworld.org/forums/e-class-w...-yourself.html

WesleyCole

Thanks guys I am leaning to hoses....The only way to lock and unlock from the inside is with the pull up, push down old school pull knobs....there is no auto lock button on door side console or dash. Pushing either door lock down or pulling up is like an act by Hercules and I am afraid I will break something. Locks work perfect with key. That being the case how could it be vacuum because doesnt key trigger the vacuum?

stormtigers

I believe they are mechanical with vacuum assisted actuators.
What I found was the lines had stretched to the extent that it was losing pressure depending on how long it had been since last actuated. So sometimes it would open with the button other times not.

So whilst there was sufficient pressure in the line at the lock to enable the door to unlocks, there was not sufficient at the pump area to activate through the lines to the point of activation.

The key therefore apparently triggers the pressure directly to the actuators mechanically rather than using the central locking pump to generate the pressure through the system.

I hope that makes sense. Maybe this W123 diagram of the system might help explain it better.
The location of the pump etc is not relevant, more what is going in and out and the fact there are check valves which sort of implies that pressure is held at the lock for manual opening.


It's a 5 minute job to pull the rear seat bottom, remove the foam that covers the pump and you should be able to see for yourself the hoses I am referring to. You can see below the red hose (old one) opening is considerably bigger than the black hose (new one).

I HAVE NOT HAD A PROBLEM SINCE REPLACING THEM !

Rock

Seems pretty good to me.

RBYCC

The early cars were not designed to lock from the inside with the doors open or key in ignition.
It was a Teutonic method to prevent not locking your keys in the car

WesleyCole

thanks this helps alot I will check the hoses asap, thanks again

WesleyCole

thanks will check mine for Teutonic method, before hoses

WesleyCole

and the winner is...............Teutonic method which was never mentioned anywhere in the MB Owners Guide and never found using Google... Thanks RBYCC

Now a follow up question. I noticed that the sound from under the right rear passenger seat last about 30 + seconds before it quits which allows me to lock or unlock. Is this extended time a signal that something is going bad or that there is a leak. If so, any clues? If not, hey I can unlock my doors

stormtigers

I cry FOUL - I mis-read the question - Appeal to the Judges !
I thought you said the button would sometimes not lock/unlock from outside (sob sob)
The dog ate my homework, my little brother scribbled on my notes...ummmm

Glad you resolved. Had I re-read the question my answer would have been same as RBYCC.

WesleyCole

haha StormTiger, you can still answer the "is something about to go bad" follow up question

stormtigers

Well then I will go back to my suggestion, get in there and have a look. It could be the pump is taking longer to pressure up due to a leak.
Not sure if it has a "pressure switch internally" or is timed to do it's task.
Would make sense that if it is leaking it's working longer to do it's job.
Best way rip the seat out to expose the pump and then button lock it (with doors closed ) and see if you can see anything amiss in the hose department or from the pump itself.

WesleyCole

thanks

Saijin_Naib

Oh zee Germans. Gotta love how they thought about things.