w123 300d trunk wont open
 

Hi, So I have my car finally delivered but, my trunk lock wont turn and vacuum doesnt work.

Does the key work in the glovebox? It's possible you have a Valet key which will operate the door and ignition, but not glovebox and trunk.

Hi, Thanks for the reply.

I only have two keys with me one for the doors one for the ignition. (both squared head)

My glovebox doesnt have the keyhole.

When my W123 300D was left not driven at all for many years, it became very difficult to open the trunk. But since refurbishing the car and now driving it two or three times a week, the vacuum trunk lock system works normally again, and the trunk opens as it should.
Maybe if you are able to drive the car that will restore the vacuum trunk mechanism, I just don't know how long a drive it would take, though.

? How to do you put pressure on the vacuum lock and open it?

I have a vacuum problem in this car. The engine will only shut off when drivers door is locked.

I just did a web search using the following query:
how to find leak in the vacuum door and trunk locks of W123 mercedes

There are a few of the first sites listed from the search, you can do the same search and scroll further down the search results to see if anything looks promising. I haven't looked at any of them, so am just posting them for you in case any of them may be of help in your situation. If these aren't what you need, you might try doing a different web search with a query that better matches your car's problem. Wish I could be of more help!:

The Basics of Tracking Down Vacuum Leaks
http://www.peachparts.com/shopforum/diesel-discussion/312002-basics-tracking-down-vacuum-leaks.html


Mercedes 123 Vacuum Door Lock Diagnosis Tip by Kent Bergsma
https://www.youtube.com/watch?v=HoVVUMvEPx8


Mercedes-Benz W123 Vacuum Door Lock System
This video gives a brief description of the overall vacuum system and shows component locations, actual parts, and system diagnostics for the W123 door locks.
https://www.youtube.com/watch?v=Axn3HD_wjL8


Repairing Mercedes W123 Door Lock Master Vacuum Switch
https://www.ifixit.com/Guide/Repairing+Mercedes+W123+Door+Lock+Master+Vacuum+Switch/20887


How to Test a W123 Vacuum Door Lock Actuator
https://**************.com/problems/vacuum/how-test-a-w123-vacuum-door-lock-actuator

The following site has good pictures of the course that the vacuum tubes take in the W123:

Mercedes W123 Vacuum Lock System Diagnosis Technique
https://www.ifixit.com/Guide/Mercedes+W123+Vacuum+Lock+System+Diagnosis+Technique/20201

How to open from the back side:

https://www.peachparts.com/Wikka/W123TrunkBreakIn

I would try an other source of vacuum first. In those vacuum threads locate where the locking system check valve is under the hood. Mine has one nipple on the vacuum supply side and 2 nipples with 2 lines connected going to the locking system. Connect your vacuum source to the single vacuum supply side nipple.

If you can't restore the stock vacuum:
Due to the vacuum reservoir on the locking system I think it would take a lot of pumping whith a hand held vacuum tester to supply the vacuum.
Ideal would be one of those vacuum pump pumps people use when they recharge their air confiding system.
If you have a gasoline car you could pull up to the Mercedes and connect the gasser manifold vacuum with a long vacuum hose to the Mercedes.

I don't know if the Dealers are still cutting new Keys using the vin or not. If they are you could get a new key made and hope the Trunk Lock matches it.

I opted to buy a used Trunk Lock with a key on eBay it also came with Door Locks and Ignition Lock Tumbler. I disconnected the vacuum from the locking system and just do it manually and I like it better that way. No more need to worry about vacuum lock system failures.

Ah I forgot it to do this......... Thank you.

I lose somewhere between the doors vacuum. Haven't got tester yet.

Should be able to unlock with the key. If you can't, squirt some TEFLON-BASED lubricant into the keyhole. Not WD40, not graphite, not oil of any kind. Insert the key and wiggle wiggle. Make take some time but it will eventually turn and unlock. Remember, you must press the button in to open.

I'm guessing this is the problem.

It gets more complicated with the 90's MB where the trunk lock key has 3 positions and pressing the button is required. I'm not sure if the older ones had 3 positions.

Stuck W123 Trunk Lock
 

Yes, the W123's also use three positions, turn the key as far as it'll go counterclockwise and hold it there as you push the button in , that's how it works when the lock is stuck in the vacuum locked position .

I'm surprised one said 'no oil / graphite' as I always use liquid graphite to both loosen up old rusted solid locks and to do the annual lubrication all key locks need .

That would be me Nate. Oil, however light is not a good choice for a lock exposed to the elements. It holds dirt/grit and will eventually make sticking tumblers worse. Graphite is o.k. if used sparingly but most pack the tumbler with that stuff.

The teflon lube was a fix shown to me by a local locksmith when I had a similar problem on my W123. I squirted a lot of that stuff into the lock to flush out all the old mung produced by oil over the years and it eventually worked.