New noise, just started (car is 85, 190E 2.3, 130K miles) - when the engine is on and the car in park, there's a humming/grinding/chirping noise from the bottom, rear of the car. If you switch the car off, then bring the ignition to "ON" position (without cranking), it makes a loud noise (same type) for a split second, then no noise. Then when you start the car, the same noise starts again from the bottom rear. What could it be? I am going to the tech after 2-3 days anyway - could it be something urgent, or can it wait a couple of days? Thanks a lot.

Your fuel pump is probobly going to die soon from what your describing: bottom rear, split second in on position...... I am 90% sure it is your fuel pump. No telling how long it will last if it sounds that bad.
Good Luck!
Adam

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Current Stable:
01 ML55 AMG
92 500E (a few mods)
87 300E (lots of mods)
00 Chevy 3500HD Diesel Box Truck
68 18' Donzi Marine
06 GT i-Drive7 1.0 Mountain Bike (with GPS!)

PREVIOUSLY OWNED:83 300SD, 87 420SEL, 88 420SEL, 90 420SEL, 86 560SEL, 86 190E 2.3-16V AMG, 94 E320

Thanks, Adam. Is there anything I can do if it conks out on me on the way to the mechanic tomorrow morning, other than getting it towed?

Hummmm,,, Not really, If you are hearing grinding fom the pump it may be only seconds before it locks up. the warning signs are usually loud humming and then you may only have a couple of days. If your good at simple repairs you can do it yourself. It will only take about 30 minuites to do with the proper tools. mostly metric open end renches. This will save you from a possible tow.

Oh, also, the pump is only $202.44 on fastlane. You could either purchase one from Phil tomarrow and get it the next day for a very reasonable shipping charge. You can also use it as a price comparason to what the dealer near you wants for one.
Hope this helps!
Adam

This has been very helpful. Thanks once again. I'll let everyone know how it goes today.