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W-1-2-3 Go!
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Discussion Starter #1
I was bored the other night while waiting in the car with the engine OFF, so I cycled through the locks and counted how many I could reach.

The owner's manual says it should reach FIVE (5) cycles (lock AND unlock, or vice versa) with the original vacuum system. I managed to squeeze the factory 5 cycles easily, with the 5th cycle slightly slower than the first 4, and on top of that, 1 more extra (6th) cycle that barely made it (took so much longer, but the last door lock plunger reached maximum height).

This is with new door actuators, new master driver door switch, new fuel filler actuator, and original trunk vacuum actuator.

When I haven't figured out where the vacuum leak was (it's in the climate control system, isolated temporarily until I find time to get it fixed), the door locks would NOT go beyond 1 cycle. Needless to say, I'm very happy!
 

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1984 300D, 1983 300TD, 1995 E300
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435 Posts
Um, how about 2/3 of cycle?

I've got a large vacuum leak (or many small ones), so my passenger's goes up, the rear passenger's goes up and the rear driver's arm is broken so the plunger just sits in the hole no matter what.

That 'arm' + a million feet of hose and tubing is a Xmas present to poor unemployed me. My brother in law is going to be in town for Xmas and the car is going to get some of the attention it deserves.
 

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Five cycles for the 240D now that its fixed with many new parts. Not sure about the 300TD, probably get five out of it but I noticed recently that it loses vacuum over the course of two nights.
 

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82' Euro 240D 84' 300D 01' SLK320 6 Speed Sport!
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MBeige...Show off:mad::D I can only get 1 cycle.
Its a summer Job I plan on tackling, not sure of where the leak is though, and the passengers side door will lock itself as soon as you unlock it with a key..
 

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W-1-2-3 Go!
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Discussion Starter #5
Congrats Matt! Tracing down vacuum leaks sucks! (or, doesn't...pun intended :))

MBeige...Show off:mad::D I can only get 1 cycle.
Its a summer Job I plan on tackling, not sure of where the leak is though, and the passengers side door will lock itself as soon as you unlock it with a key..
If this thread popped up a few months back I'd probably say the same myself, because back then as I mentioned I had a bad leak. :D

Note that vacuum leaks can show symptoms in other systems, like my climate control vacuum leak exhibited itself through the door locks (possibly because it's also closer to the reservoir? Not sure... :confused: )
 

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Congrats Matt! Tracing down vacuum leaks sucks! (or, doesn't...pun intended :))



If this thread popped up a few months back I'd probably say the same myself, because back then as I mentioned I had a bad leak. :D

Note that vacuum leaks can show symptoms in other systems, like my climate control vacuum leak exhibited itself through the door locks (possibly because it's also closer to the reservoir? Not sure... :confused: )
Thanks. I think there were about five confirmed leaks. Never did figure out if the door switch was bad, but it got replaced anyways. Running new line through the door was probably the most "fun".

After all was done, I could get the locks to work with the handpump from the engine bay, but not when directly plugged into the main vacuum line. Turned out that the brown lines attached to the iginition were reversed by the PO causing weird non-op locks and no engine shut-off.
 

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1991 300zx 2+2 @ 129k Miles.
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Congrats Matt! Tracing down vacuum leaks sucks! (or, doesn't...pun intended :))

Note that vacuum leaks can show symptoms in other systems, like my climate control vacuum leak exhibited itself through the door locks (possibly because it's also closer to the reservoir? Not sure... :confused: )
Exactly.

My door locks work great after stopping the car, but after a few hours, it acts up again. I am not 100%, but I am pretty sure that my leak is with the climate control system. Hitting buttons seems to do absolutely nothing...air comes out everywhere. the only button that I can confirm working is the off button, and it is half-assed.
 

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W-1-2-3 Go!
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Discussion Starter #8
Matt, when I replaced the 3 door vacuum actuators, master switch and fuel filler lid actuator, I may have pulled good ones. They're original, but I misdiagnosed thinking that the central locks had the leak.

When the good ones started acting up, I realized I replaced the wrong parts after all. So I've tracked the leak down to the climate control system, isolated that system and now the entire central locking system works perfect. It holds vacuum (5 cycles!) for a week.

Exactly.

My door locks work great after stopping the car, but after a few hours, it acts up again. I am not 100%, but I am pretty sure that my leak is with the climate control system. Hitting buttons seems to do absolutely nothing...air comes out everywhere. the only button that I can confirm working is the off button, and it is half-assed.
The way I was able to isolate the climate control system was to place a check valve (I had a blue/black valve, but any 1 way valve should work) BACKWARDS. So if the valve has an arrow, it should point back to the firewall. This valve was placed between the green vacuum line and the 4-way connector.

I have yet to fully diagnose the specific cause of the leak, but I have a suspicion it's the main air flap/recirculation flap actuator. Pulled the driver side underdash panel and tested the footwell and defrost actuators and both were good.

I know some members have converted to electric door lock actuators in place of the vacuum, OR have piggybacked on the vacuum actuators and just added one electric actuator on the driver door to remotely trigger the vacuum system to lock or unlock with a button on the key fob.
 

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85 300D, 84 300D, 05 Mustang GT Vert, 11 VW JSW TDI, 95 Del Sol, 88 IROC, 95 Villager, 04 Wrangler
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I've done three without thinking about it, so not sure how many it'll do.
 

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1981 240D
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I get 3/4 of a cycle. That is to say, When I shut down the engine, if I lock the doors immediately all doors except the front passenger will lock. Only the driver's door will unlock. If I wait more than 5 minutes after shutting the engine down, only the driver's door will work. I haven't done anything to fix the vacuum leak. I know where it is. There is a broken vacuum hose that goes into the front passenger door. That is why it doesn't work. I have to tear the door apart soon to replace the window motor, so I am in no hurry to fix it. I have bigger issues right now.
 

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1984 300D
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Mine will do 5 or 6 cycles even after sitting for a few weeks. I thought this was low and was going to look into it in the Spring. So maybe I don't have any vacuum issues after all.
 

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1979 280CE
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I just tried it on my 123 coupe, got 7 cycles.
 
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