W126, BENZ AID - COMMON QUESTIONS AND ANSWERS

1983 300SD vacuum diagnosis

Hi, All,

I have isolated a vacuum problem to the red/green plastic line that services (I think) interior switches and servos: with this red/green line attached to its fitting on the vac system, system pressure drops from 45m/g to 15m/g or less with the engine running. When the car is turned OFF, the line holds vacuum (??); when the car is ON, its as if it's open on the other end, bleeding off vacuum (brakes go hard after 2-3 pumps; engine won't shut off if at idle awhile).

Does this behavior suggest a specific component that I should go after?

Thanks in advance!

Chassis Model Number

W126

Forums

Diesel Engine Specific Aid

1985 w126 300sd cental locking system failure to lock

I have posted this question on a few other Mercedes Forums with no assistance. So...I have paid the 30 bucks for hopefully some light to be shed.

I have a strange problem with my central locks.

The problem I am having is that locking any controlling (driver passenger trunk)lock will cause all locks to unlock but it is impossible to lock the doors. I obviously have no leaks.

What I have so far.
I have run the pump on the bench and if I ground any of the 3 pins the pump pulls untill the vac switch makes. Then if I apply 12v to a pin the pump pushes until the press switch makes. This seems to make sense. Keep in mind I did not test the pump with a constant 12v on any pins and I will try that later today.

I also tested the wiring in the car and all is correct.

Chassis Model Number

W126

Forums

Body and Interior Specific Aid

1983 300d white smoke, no power

need help. i have a 1983 300d 150k on the clock. hard start when cold, heavy white smoke through out operating temperture, no power. compression at 330psi all cylinders.check diesel fuel, ok. replaced all fuel filters and in tank screen. replaced all glow plugs,relay. replaced all injector nozzles. replaced all fuel hoses and plastic lines. problem still exist.performed timing chain stretch. Found 6 degrees after tdc. any ideas?

Chassis Model Number

W123

Forums

Diesel Engine Specific Aid

1985 300D - rhythmic thumping sound near transmission ??

There is a rhythmic thumping/knocking sound coming, I believe, from the area of the transmission. It is really audible inside the car, less so when outside or under the car. In the car it is difficult to pinpoint as it seems to move around depending on where my head is at, however I'm pretty sure it is strongest around the transmission hump in the car.

Here are a few other details:

* The noise seems worst/loudest in the morning.

* Doesn't seem to affect driving of the car.

Chassis Model Number

W123

Forums

Transmission / Suspension Specific Aid

220D vacuum line tap

I have a '71 220D with a mystery vacuum tap on the main line between vacuum pump and power brake booster.
It's unconnected, and there's also a disconnected hard line up by the firewall, but it doesn't have the length to connect to the brake-line tap. (These are the only vacuum fittings on the car.) That line is split by some sort of check valve or diaphragm/filter, and it disappears under the driver's side fender, right under the windshield corner. It's green, and it doesn't seem to reappear under the dash.
I thought at first it had something to do with the windshield-washer pump, but that's foot-operated, and I've successfully reconnected that.
Any idea on what the mystery line/tap is? I've got some MercedesSource hard line and fittings to reconnect things, but how and what?

Chassis Model Number

W115

Forums

Diesel Engine Specific Aid

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