I'm replacing my first piston type compressor on a 1979 - 240D mercedes and would greatly appreciate any sound advice. I've replaced many modern compressors but never one this old. Does the system require addition of oil to the gas stream like a modern system? If so what type and how much? Do you need to add oil to the crankcase of the York piston compressor? If so what type and how much? When I disassembled the existing system there was no oil in the gas stream but there was oil in the old compressor crankcase. Thanks for any help.

There are two chambers in the York style compressor that hold most of the oil. Add it during the fill just as you would a more modern system and it'll go to where it needs to be. If you do not have to turn the old compressor in for a core, I'd be interested in it (or just the top plate). I posted a thread at http://www.peachparts.com/shopforum/showthread.php?t=153248 with pictures of the part I need.

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85 300CD
83 300TD
78 240D (daughter)

It's been a long time since I worked with one of these compressors but IIRC the York compressor has a oil sump and oil is NOT added to the refrigerant circulation system as is done in contemporary A/C systems. I remember the shop manual had the dimensions of a self made dipstick that was used to measure the oil level in the compressor, I don't recall what lubricant was used in the sump. I no longer have my W115 manuals, maybe somebody that has a set will provide a better answer.

Another cool thing about the early York compressors is that the top plate of the compressor has a valve body that will permit you to use the compressor to evacuate the system prior to charging - no vacuum pump is needed.