Garage > Mechanicals

Central locking troubleshooting and repair

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raueda1:
Edit:
Oops, wait!  the stupidist question was easily answered.  Somehow I missed it.   ???  The manual has leakdown specs which somehow I missed.  I'll compare with my results.  Still, any wisdom is always nice.

-------------------------------------------------
OMG, I guess this must be the stupidest question ever posted, but here goes.   :o

When is a vacuum leak really a leak?  I've been trying to go through the process but it seems like everything leaks, at least to some small extent.  I'm using an electric vacuum pump and the usual manifold vac gauge.  The pump will pull about 23 in Hg / 60 cm Hg.

1. Does the vacuum on a given circuit need to hold, say, 99.9% overnight? 
2. Or is it "OK" if it just slowly drops over several hours? 
3. Or is it only a leak if the pump can't pull any vacuum at all (i.e, vacuum never gets to what the pump can pull and drops to zero immediately)?   

I'm seeing various examples of 2 and 3 but never 1.  Is 1 even possible ("nature abhors a vacuum")?   I have no experience or context here. Any wisdom appreciated.  Thanks and cheers,

BCK1963:
I guess that there is no ultimate truth.
All components age with time and in particular the rubber lids of the actuators slowly become porous even if they 'feel' like still being flexible.
Given the reports of proud owners that their system still worked after several weeks and even months, your reading on the pump manometer should come close to 1. Please mind that you test single spots but the capacity of holding the vacuum is the sum of all individual spots.

I found my actuator for the gas tank lid being faulty and I cut it off. Now the system holds the vacuum for 3 - 4weeks which is ok for me.

If you want your vacuum system being as perfect as the appearance of your engine compartment ..... good luck :-)

raueda1:

--- Quote from: BCK1963 on 12 April 2021, 09:38 AM ---I guess that there is no ultimate truth.
All components age with time and in particular the rubber lids of the actuators slowly become porous even if they 'feel' like still being flexible.
Given the reports of proud owners that their system still worked after several weeks and even months, your reading on the pump manometer should come close to 1. Please mind that you test single spots but the capacity of holding the vacuum is the sum of all individual spots.

I found my actuator for the gas tank lid being faulty and I cut it off. Now the system holds the vacuum for 3 - 4weeks which is ok for me.

If you want your vacuum system being as perfect as the appearance of your engine compartment ..... good luck :-)

--- End quote ---
LOL, it's not so hard to make the engine bay look good when the engine is out of the car.  But yeah, I take your point.  In any case, I did progress a bit and discovered that the door switch is entirely useless.  Regardless of the piston position there's leakage between the respective connections.  The system actually worked extremely well until it didn't.  It was a kind of overnight failure from "works perfectly" to "doesn't work at all."  So I guess the switch just completely let go.  My hope is that replacing it returns the system to what it was before.  Cheers,

raueda1:
OK, made some progress.  As usual it's 2 steps forward, one step back.

The good:  The door switch was totally inoperable as mentioned above.  New one is on order.  I further tested the locking system by pulling vacuum on the respective locking and unlocking lines on the switch.  The whole locking system works perfectly, no leaks whatever anywhere (doors, trunk, fuel flap).  This is great news and simplifies my life.  :D

The bad: The line to the trunk reservoir seems to leak.  This is the gray-yellow line that snakes from the engine compartment to the floor to the trunk.  It will have to be replaced. I envision a lot of tedious and annoying interior disassembly.   I'm envisioning the possibility of using the old tubing to pull the new tubing through, kind of like pulling wire through a wall with a fish-tape.  Maybe in several sections and connecting them.  Are there any shortcuts?  And is there any sense in trying to source the correctly colored tubing?  Keeping the right color would be a nice touch.

And the ugly: The other lines (gray-red,  green-yellow and blue-gray) control the heating.  The blue-grey goes to the front vac. reservoir and is OK.  Both of the others leak very fast, which I assume is bad.  Practically speaking this isn't necessarily the worst thing.  My heater core is disconnected cause of a small leak, so the heater doesn't work anyway.  But I don't drive the car when it's cold and the AC still blows sub-arctic cold.  Nevertheless, it would nice to fix it while I'm in there.  I'll look at the manual carefully, but any tips, tricks or comments would be terrific.

I'll report more when there's more to report.  Thanks for the help to this point and cheers,

ptashek:

--- Quote from: raueda1 on 14 April 2021, 09:27 AM ---The bad: The line to the trunk reservoir seems to leak.

--- End quote ---

I'm assuming you've plugged it at the reservoir end, before testing? Could be just the grommet otherwise.

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