Fixed my door locks!!!

Well, I couldn't quite figure out my MB factory manual instructions but I decided to just start fidgeting around anyway. All I would do was to pump with the vaccum tester to around 20 or so, then push the pin in to see how far the pressure dropped.
1st I wanted to make sure the reservoir and vacuum line from the reservoir were OK so I started with those: they held pressure fine.
Then I started with the Green and Yellow line going from the engine compartment into the cabin. It held pressure fine.
then I went to the Red and Yellow: nope, would not hold pressure. So I tested the line going towards the driver's back seat, it was OK. Then I tested the one going to the passenger's side over the transmission hump: no, would not hold pressure. I replaced the line but it still would not hold so I continued on the passenger side: the one going to the front door was fine, the one going to the back door was fine, it was the one going back to the fuel filler door and rear door (I've got a wagon) that was leaking. I had to remove the B Pillar and carpeting over the rear wheel, just in front of the jack and 1st aid kit compartment. There was a 3-way splitting the one into two: 1 to the gas cap door and 1 to the rear door lock (it actually goes up the B pillar and under the headliner to the rear of the car. The gas cap line was leaking, the rear door was not. I simply plugged off the fuel filler door line to remove it from the circuit (I don't care if my fuel filler door locks or not).
So far, all 5 doors lock and unlock even after the car sits for up to 45 minutes. Time will tell if I've taken care of everything or not but so far I'm pleased. hope this is helpful to somebody! My experience is that you've just got to chase down the leak until you're to the end of the circuit....

[Rick Miley]

That's great that you fixed the locks. Yes, you just have to keep tinkering until you find the leak. Golf tees work great for plugging the lines to isolate branches of the curcuit. I'm disappointed to see this, though:

Originally posted by shawnster
I simply plugged off the fuel filler door line to remove it from the circuit (I don't care if my fuel filler door locks or not).

It's little things like this that don't get fixed that cause a car to go downhill. One at a time things break and soon you find yourself with a laundry list of problems that really detract from the car at resale time. You know, the vacuum pods are only around $20 at Fastlane.

Rick,
Some of us still have to decide at times between $20 for a non-essential fuel filler door lock and a very essential $20 oil and filter change.

Hey, I've got a PayPal account, send me the $20 and I promise I'll fix my fuel filler door so you'll feel better about my laundry list.

Actually, I think I've done a pretty good job of keeping the "laundry list" on the short side, but thanks for your concern.

[Rick Miley]

shawnster, I've been following all your posts about making improvements to the car and it sounds like you're doing a great job.

My post was meant to be encouraging and came out as derogatory. For that, I apologize.

84 300DT

1. Connected MityVac (MV) on the yellow check valve by the brake booster
2. Door locks are UNLOCKED
3. Pumped MV to 10 inches of vacuum
4. LOCKED the doors on the driver’s side. All doors locked fine but quickly loss vacuum.
5. Pumped the MV to 10 inches of vacuum again quickly loss vacuum.
6. UNLOCKED all doors
7. Pumped the MV to 10 inches of vacuum, NO loss of vacuum

Summary: Doors UNLOCKED – it holds vacuum. Doors LOCKED – does not hold vacuum.

Logic tells me that the vacuum leak is in the INTERLOCKING (yellow-red) line but somewhere in this Forum I read (I could be totally wrong) that the problem is in the UNLOCKING (yellow green) line.

Which line should I proceed to check?

Thank you all for your time.

[Rick Miley]

The diaphrams in the fuel filler and trunk pods are not as robust as the ones in the doors. Furthermore, they are not under vacuum when the system is unlocked, only when locked. So I would look there first. Start at the junctions under the plastic cover in the passenger side footwell. There should be two with red stripes that go toward the back seat. One of those locks the the right rear door and the other one locks the trunk and fuel filler.

shawnster,

That's the spirit! You have the makings of a troubleshooter. The most important thing is to just grab that trouble by the throat and don't let go. You keep working and testing and reasoning it out until you find your culprit. That's exactly what you did.

Thumbs up for shawnster!

Good work,

[R Leo]

This must have been 'repair your vacuum system weekend' becoz, Lilly's locks are working now too!

For a while now, SWMBO has been complaining that Lilly will lock with the key intermittently. So, I took a half-hour last evening and chased down a couple of leaks in the vac sys and also discovered that the LR door's vac pod has an intermittent leak.

I fixed the leaks at the filler lid's lock 'ys' plus isolated the LR door pod from the system and would you believe it? The doggone thing still had enough vacuum this morning to lock and unlock the remaining doors 3 times. Neato!

A door pod is now on order and I'm inspired...I may even get the vac system working on Marlene so that you don't have to remember to lock the drivers's door before you can shut the engine down.

[Rick Miley]

You guys always forget to look at the dates on the posts. Most of this thread was from last June.

[R Leo]

Originally posted by Rick Miley
You guys always forget to look at the dates on the posts. Most of this thread was from last June.

Rick,
I count on you for my reality checks.

Oh well, at my age I guess I live too much in the past anyway.

Have a great day,

Originally posted by 84W123DT
84 300DT

1. Connected MityVac (MV) on the yellow check valve by the brake booster
2. Door locks are UNLOCKED
3. Pumped MV to 10 inches of vacuum
4. LOCKED the doors on the driver’s side. All doors locked fine but quickly loss vacuum.
5. Pumped the MV to 10 inches of vacuum again quickly loss vacuum.
6. UNLOCKED all doors
7. Pumped the MV to 10 inches of vacuum, NO loss of vacuum

Summary: Doors UNLOCKED – it holds vacuum. Doors LOCKED – does not hold vacuum.

Logic tells me that the vacuum leak is in the INTERLOCKING (yellow-red) line but somewhere in this Forum I read (I could be totally wrong) that the problem is in the UNLOCKING (yellow green) line.

Which line should I proceed to check?

Thank you all for your time.

Replaced the leaking Vacuum Element and the 3 way rubber connectors for the fuel door and all is well!

[Fuzzball]

Thanks to Speedy300D, I now have working locks as of this evening....

Speedy sold me the pump and it's working like a charm!

Not bad, overnight delivery form California either!

Again, Thanks Speedy300D!!

[oldnavy]

well I have door looks that work and will hold vacuum for at least 3 days and will cycle 6 or 8 times no problem. The trunk and fuel door however do not work. Checked the easy one first, trunk pod is fine. Looks like it will be a bad fuel door pod, but it still makes me wonder why my door locks all work. Must be check valves somewhere.

I'll check fuel door pod tomorrow morning, to hot and humid now for more work. :p

It sounds like the trunk and the fuel door flap have been bypassed or taken out of the loop.