isolated a scratching and squeeking noise to the power steering pump. its most noticeable on startup, lasts for maybe 10-15 minutes, then quiets down. louder when it's colder outside. belt and tension are fine, fluid level and filter are fine, and theres no noticeable difference in steering control. louder at idle, quiets down under load. pump i'm assuming is original to the car, so it's got well over 300,000 miles on it.

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1981 NA 300D 310k miles

PS pumps generally have sleeve bearings, not sure about yours.

While the engine is running, mist / spray some water on the belts and see if the noise goes away. From your description it sounds like belt noise.

Don't use belt dressing, it will make a real mess in the long term.

Does your power steering pump have a filter and if yes, has it been changed lately ?

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/showthread.php?t=156207&highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html