Leak from oil guage on dashboard 1984 300TD
 

How do I go about replacing the leaking oil guage on my 1984 300TD? Recently a steady drip. drip, drip has been occuring on my accelerator foot as the oil line is leaking. Is there a replacement? Would it be easier to do something else? I'm about to go over 304,000 miles.

Other possible sources of the drip
 

There is a good chance that the culprit is not the guage itself, but the plastic hose or the connector gadget and neither of these is difficult or expensive to replace, if you don't mind working with your head under the dash, so you need to get the bottom trim panel off the dash (just a few screws under oval covers) and trace down the exact source of the leak first. In the meantime, the oil flow can be blocked by removing the fitting on the engine and inserting a plug, but I don't like the idea of driving without an oil pressure guage, ever, and especially not on a vehicle with that many miles.

The accelerator pedal is a bit of a distance from the oil pressure gauge on the W123. Are you certain the gauge is the source of your leak?

Its possible the vacuum pump's diaphragm has ruptured, allowing oil to contaminate vacuum lines and hoses that supply, among other things, the vacuum switch (attached to the ignition lock) that controls engine shutoff. This switch is closer to the accelerator pedal and may be the source of your leak. I've seen these drip oil over time when the vacuum pump fault is left uncorrected.

Pull your instrument cluster (use M-B's pulling hooks or make your own) and inspect the back of the fuel/oil press/water temp instrument cluster. If the cluster is dry, the gauge is not your problem and you will need to look elsewhere for the leak. The cluster can be pulled without having to remove the lower dash access panel.

Have never seen a supply hose failure; oil loss at the cluster is typically due to a loose nut (10 mm) that connects the hose to the gauge. Additionally, the oil pressure gauge has a diaphragm that can rupture; in that case the cluster will need to be replaced.