I read many posts regarding central lock failure but could not find help with my problem. System failed. I have lumbar seats so there are 2 ports on the pump. The vacuum port for the locks was broken off. I used epoxy plastic bonder from Loctite to repair and put it all back in place. The locks worked to some extent. The driver and passenger door would lock and unlock all doors, and the truck but not the fuel door. I kept working with the system and after a while the pump quit working. It was very warm. I let it cool down and it started running again. Now nothing works. I can only lock the driver or passenger door individually with the master key. The "C" and "A" fuses are good. At a loss as to what to do next. My 1991300E 4matic has 178K on it. Any and all suggestions will be greatly appreciated.

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Handyjay

Here is the latest. Apparently the leaking vacuum line caused the pump motor to run to much and over heated. The heat melted the very fragile shaft to rotor plastic piece. The result the pump motor would run but no vacuum or pressure to the systems. Now the problem is finding a new pump without spending over 10% of the car value. Best I have found so far $420. Any ideas where the best prices are for Mercedes parts?

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Handyjay

Junk yard

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1990 190E 3.0L

The lumbar seats had a different pump than the standard seats.
You've noted the second port for the seats.

If you wanted to defeat the seats, a standard pump should restore the locking function. I've found the lumbar option to be quite rare, and unreliable as the system ages. The bladders get leaks in them, causing the pump to run more often.

Contrary to earlier vacuum systems, the W124 uses a negative and positive pressure to actuate a single diaphragm, vice the older style of having vacuum ports on both sides of the diaphragm.

W126 cars should have a similar pump to the W124.

Again, the hard (expensive) part will be to find a two port pump....

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

Yes I am finding that the 2 port pumps are non existent used. Thanks for the info. Will continue looking. Do you know if #124 8 1248 my part number was replaced with 124 800 2848? The later one is listed in Pelican. Looks the same except for the color of the removable cover. Mine is white the other is tanish.

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Handyjay

You might consider using 2 pumps too.

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1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

How does the 2 port pump work? One side is pressure for the lumbar seats and is connected to the trunk and gas lid. The vacuum port has three connections. Does the pump motor reverse to provide pressure to the seats?
I repaired or tried to repair the pump with epoxy on the shaft and rotor drive. It does not appear to be working to well after a couple of days. Now the two front doors lock with the key but not the rear doors. This makes me think the pump is running(I can hear it) but maybe slipping and not providing enough vacuum to operate everything. I assume the pump is controlled with a timer so it will not run indefinitely if a line or devise is leaking in the system. Still looking for the correct pump but not having any luck now even for a new one.

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Handyjay

can you try retrofitting a W140 model pump that assists in door closing?

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Not sure but will try to check it out. On the 2 port pump like I have, I am now not sure which port to connect the yellow line that goes to the trunk and gas lid or the 3 line connector. I put vacuum on the yellow line and every thing locked. Do the electronics reverse the motor and/or open/close valves in the pump unit? A very complicated system it seems to me.

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Handyjay

It's been a while since I've had a car with lumbar, but I think the pump has one port dedicated to the locks, and one port dedicated to the seats.

I recall the the pump was activated for the seats by selecting the desired pressure on the switch next to the console. If you selected a bladder, you could either pump it up (pump pressure) or relax it (dump pressure). The control unit next to the console reminded me of the euro headlight adjust switch. With the headlight leveling switch the switch regulated the amount of vacuum fed to the pods in the headlights. The lumbar control feels like acts in a similar manner, only regulating pressure, vice vacuum.

It sounded like the dump was at the seat, and not a function of the pump.

Before you try to overthink the pump, make sure the individual bladders are all good, if not, you'll burn out the next pump, too. My experience gives me the opinion that there is a high rate of failure in these bladders as they age.

Also, the pump location under the rear seat is limited. The pump is enclosed by a soft, sound deadening material and there is not much room in the floor depression for extra stuff. There's a reason that the pump is covered in a thick foam......

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles

I can confirm that a single inlet pump will work on a car that originally had a dual port pump. (w126 and w124's)

My 420sel has the lumbar driver seat, and the dual hookup pump.
The connections are the same between the single and dual pump. the only difference is, the in the straight 3 wire plug that feeds power (not the round 3 pin from the door lock switches). the (pressure) side of the pump is activated from the center pin where there's another wire. But the single and dual pumps will interchange and plug in.

When I first got my car, I discovered that neither the door locks or the lumbar seat worked. Upon closer inspection, I found the pump and circuit board totally burnt up inside the case.

I picked up a single pump model from the wrecker, plugged it in, and I had door locks. But one little problem. the pump would continue to run for about 30sec after either a unlock or lock. Indicating some type of air leak.

This is a good tidbit to inspect for those grabbing these aged pumps from 20+ year old cars. Because it was a super easy fix.

I determined that the pump was leaking internally, so I opened up the pump, and determined I had a leak on both sides of the bellows plunger that tells the pump if it has reached full vac(to lock) or full pressure(unlock). I disassembled, and fitted 2 small o-rings to either side of the plunger shaft to snug up the seal. Having a properly working system saves a lot of wear and tare on the motor.
Also when in there, clean up the contacts for the activation relays, you will be surprised how dirty it gets inside these pumps. This will save you hours of headaches for when your trying to mess around with your door lock switches, thinking they are bad, and the pump must be good. LOL

Wire in one of those cheapie remote door lock moduels into the pump, and your set! One of the best mods ive done to date!

Pump has been running great for 2+ years!

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Just my MB's:
1990 420sel - Winter DD - 410,000km
1990 560sel - absolutely showroom mint - 360,000km!