W215 Fuel Door Stuck Closed
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Joined: Dec 2007
Posts: 980
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2005 S500 Designo
W215 Fuel Door Stuck Closed
Not sure if it's a mechanical issue, or more likely a PSE issue, b/c pushing the lock or unlock button doesn't work as it should, and it's tied to the fuel door
I wouldn't know where to start, I've never had PSE issues before.
I wouldn't know where to start, I've never had PSE issues before.
Last edited by Fried Chicken; Dec 8, 2024 at 06:17 PM.
Thread Starter
Super Member
Joined: Dec 2007
Posts: 980
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2005 S500 Designo
Per WIS Document AR80.20-P-2300M I was able to remove the fuel filler flap.
It's tricky to reach, but you can squeeze your arm in between the body if you go up above the battery, and then you can reach it with your hand no problem.
It wasn't perfect, but seemed to actuate well enough. More importantly I could find no indication of leaks in the diaphragm or otherwise.
The suspicion now is it's a leak in the door lock/unlock circuit. I went around and believe I came up with the culprit: the right door hisses while locking (PSE pump applies pressure). I didn't hear it while unlocking, but if there's a leak there's a leak, and that is robbing the system of vacuum and pressure.
There is a very useful thread on this here:
https://www.benzworld.org/threads/ga...-door.3018612/
I now need to verify the part # for the door latch mechanism. The typical MB parts website for dealers says part #: 221-720-78-35, but that doesn't sound right to me.
EPC says: 215-720-16-35
If I plug that into my vendor, I get part: 215-720-16-35-64 with the annotation "Replaces 215-720-16-35"
It's tricky to reach, but you can squeeze your arm in between the body if you go up above the battery, and then you can reach it with your hand no problem.
It wasn't perfect, but seemed to actuate well enough. More importantly I could find no indication of leaks in the diaphragm or otherwise.
The suspicion now is it's a leak in the door lock/unlock circuit. I went around and believe I came up with the culprit: the right door hisses while locking (PSE pump applies pressure). I didn't hear it while unlocking, but if there's a leak there's a leak, and that is robbing the system of vacuum and pressure.
There is a very useful thread on this here:
https://www.benzworld.org/threads/ga...-door.3018612/
I now need to verify the part # for the door latch mechanism. The typical MB parts website for dealers says part #: 221-720-78-35, but that doesn't sound right to me.
EPC says: 215-720-16-35
If I plug that into my vendor, I get part: 215-720-16-35-64 with the annotation "Replaces 215-720-16-35"
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Joined: May 2020
Posts: 247
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From: Fort Worth
2005 CL55 AMG || 2005 CL65 AMG || 1989 560SEC
Mine had that issue and it turned out to be either the graphite vanes in the pump having worn out, or the valving/solenoids in the PSE pump.... Anyways, bought a random used low-mileage unit off of ebay, and swapped the control board from the bad one into the new one-- problem solved.
You can repair the door lock pretty easily, adn when you do, BE SURE to cover the cap and all surrounding interface surfaces with something like pc 7 epoxy. The vacuum actuator caps for the door lock and soft close have stupid, spindly retaining clips that get brittle and break over time. If you have functionality of the door lock/unlock/soft close still, you can clamp the current caps down and epoxy them on, without buying the repair caps.
You can repair the door lock pretty easily, adn when you do, BE SURE to cover the cap and all surrounding interface surfaces with something like pc 7 epoxy. The vacuum actuator caps for the door lock and soft close have stupid, spindly retaining clips that get brittle and break over time. If you have functionality of the door lock/unlock/soft close still, you can clamp the current caps down and epoxy them on, without buying the repair caps.
Last edited by JustTXn; Dec 10, 2024 at 12:48 AM.
Thread Starter
Super Member
Joined: Dec 2007
Posts: 980
Likes: 224
2005 S500 Designo
Mine had that issue and it turned out to be either the graphite vanes in the pump having worn out, or the valving/solenoids in the PSE pump.... Anyways, bought a random used low-mileage unit off of ebay, and swapped the control board from the bad one into the new one-- problem solved.
You can repair the door lock pretty easily, adn when you do, BE SURE to cover the cap and all surrounding interface surfaces with something like pc 7 epoxy. The vacuum actuator caps for the door lock and soft close have stupid, spindly retaining clips that get brittle and break over time. If you have functionality of the door lock/unlock/soft close still, you can clamp the current caps down and epoxy them on, without buying the repair caps.
You can repair the door lock pretty easily, adn when you do, BE SURE to cover the cap and all surrounding interface surfaces with something like pc 7 epoxy. The vacuum actuator caps for the door lock and soft close have stupid, spindly retaining clips that get brittle and break over time. If you have functionality of the door lock/unlock/soft close still, you can clamp the current caps down and epoxy them on, without buying the repair caps.
It could be the PSE pump. You're saying the door locking mechanism *can* be fixed?
Member
Joined: May 2020
Posts: 247
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From: Fort Worth
2005 CL55 AMG || 2005 CL65 AMG || 1989 560SEC
The door lock mechanism can be fixed, as long as the diaphragm within the vacuum chamber (there are 2 chambers, one for door lock, one for soft close) are not ruptured. The falure is the vacuum diaphragm cap popping off, because the plastic retaining tabs embrittle/fatigue, then break, over time.
I'm not sure of the consistency of Plasticweld, I use pc-7 because it has the consistency of play-doh, which allows for placement and molding without it dribbling off. I'm assuming the rest of the plastic cap may fatigue and fail further in the future, so I coverered the entire cap with about 1/4" of epoxy.
I'm not sure of the consistency of Plasticweld, I use pc-7 because it has the consistency of play-doh, which allows for placement and molding without it dribbling off. I'm assuming the rest of the plastic cap may fatigue and fail further in the future, so I coverered the entire cap with about 1/4" of epoxy.
Thread Starter
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Joined: Dec 2007
Posts: 980
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2005 S500 Designo
The door lock mechanism can be fixed, as long as the diaphragm within the vacuum chamber (there are 2 chambers, one for door lock, one for soft close) are not ruptured. The falure is the vacuum diaphragm cap popping off, because the plastic retaining tabs embrittle/fatigue, then break, over time.
I'm not sure of the consistency of Plasticweld, I use pc-7 because it has the consistency of play-doh, which allows for placement and molding without it dribbling off. I'm assuming the rest of the plastic cap may fatigue and fail further in the future, so I coverered the entire cap with about 1/4" of epoxy.
I'm not sure of the consistency of Plasticweld, I use pc-7 because it has the consistency of play-doh, which allows for placement and molding without it dribbling off. I'm assuming the rest of the plastic cap may fatigue and fail further in the future, so I coverered the entire cap with about 1/4" of epoxy.
I prefer this because it will fill small nooks and crannies of cracks that have formed.
Currently using it on the trunk latching mechanism to close any leaks. It says "5 minutes" but it's not 5 minutes, at least in the mild Texan winter. Maybe in the Arizona summer.
Regardless, I'll probably reach out to my dealer to see if I can order the part and return it if not necessary.
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2005 S500 Designo
I got the door apart and accessed the actuator.
There's clearly a leak. While there I also tested the new part. That one also has a rupture in it: pulling a vacuum or putting some pressure causes an audible leak.
I've reached out to the dealership parts department already.
There's clearly a leak. While there I also tested the new part. That one also has a rupture in it: pulling a vacuum or putting some pressure causes an audible leak.
I've reached out to the dealership parts department already.
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2005 S500 Designo
Thus the culprit is found, a small crack in the relief valve or whatever it is on the bladder mechanism for the pneumatic door lock:
I'm doing some digging.
The part is a made of Polyoxymethylene, a notoriously difficult to glue/bond piece. The crack happened along that one-way relief ball or whatever that thing is. I'm somewhat hesitant to simply glue it shut, but also not as that's the purview of the PSE pump. The issue is, I need something that will glue it.
I'm doing some digging.
The part is a made of Polyoxymethylene, a notoriously difficult to glue/bond piece. The crack happened along that one-way relief ball or whatever that thing is. I'm somewhat hesitant to simply glue it shut, but also not as that's the purview of the PSE pump. The issue is, I need something that will glue it.
Last edited by Fried Chicken; Jan 24, 2025 at 12:20 PM.
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From: Baltimore County, MD
'13 s212 63 p30. '06 LX470
I also like starbond isocyanurate glues for anything applicable. In that case, the product is very thin and if you don’t want it to weep too much you just get a thicker gel. The thin stuff is great for weeping into virtually anything including wood.
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2005 S500 Designo
I just did an experiment putting a bunch of tiny blobs onto the piece.
The JB Weld Plastic Weld didn't work at all really. Neither did E6000. I used some ancient 3M Trim and Plastic adhesive, but it was so old the results are suspect.
What worked really well was G/Flex 650 Epoxy and generic CA glue (superglue).
Now there's a reason Mercedes has this captured ball mechanism in their pneumatic system, and I haven't quite figured out why? I'm tempted to just glue the whole thing shut, but i'm also nervous that I'll break something if I do (say for the soft-close if the door is closed manually) or otherwise. I have not deciphered the mechanism or purpose for this captured ball.
The JB Weld Plastic Weld didn't work at all really. Neither did E6000. I used some ancient 3M Trim and Plastic adhesive, but it was so old the results are suspect.
What worked really well was G/Flex 650 Epoxy and generic CA glue (superglue).
Now there's a reason Mercedes has this captured ball mechanism in their pneumatic system, and I haven't quite figured out why? I'm tempted to just glue the whole thing shut, but i'm also nervous that I'll break something if I do (say for the soft-close if the door is closed manually) or otherwise. I have not deciphered the mechanism or purpose for this captured ball.
Last edited by Fried Chicken; Jan 27, 2025 at 11:33 AM.
