I've got a few more questions before I tackle the job of replacing the compressor and flushing, refilling with r12 this weekend.

When I took my 300cd in for evacuation of the r-134a and new valve cores, the old valve cores were covered in black funk. That definitely means the compressor seized and puked throughout the system. I now have the correct r12 mineral oil, and a quality flush agent as well. Got these from an A/C shop open since 1954, they should know what they're doing. They said I didn't need a flush gun, that I would pour in the solvent, and blast it out with my air compressor. I have a good dried/filtered air compressor so that should work. I have a few hoses to attach to the evaporator hoses so I can flush through there too. I also have the r12 and a vacuum pump/gauge station. I'll take out the Condenser to a car-wash place to blast it clean (the outside of it). I'll take the old o-rings to a parts place to match up with new ones.

Just got my new Delco R4 compressor in the mail today. It came with the stepped ports, Im wondering if I have the correct sealing rings for the job. I think people use the fat yellow ring for the Suction hose, and the green one for the Discharge. The delco manual says this is the correct configuration for compressors with 3/4" suction and 5/8" discharge ports, which is what the MB uses, right?

Replacing the R4 won't be fun. This new Delco has a smaller clutch than the other one in the car so it'll be further away from the oil cooler hoses. I think I have to remove the PS pump belt to get the compressor belt off? Still confused about the belt situation, there should be an adjusting nut on top of the compressor to loosen/tighten the belt, and loosen the compressor bolts to move the belt?

As for flushing, I'll break the lines to and from the drier, to and from the condenser, remove the expansion valve to expose the evap. lines and the two other ones, break the line where the low side valve is, the line where the high side valve is, and the suction/discharge from the compressor, and flush those out well. Am I missing anything? Diesel Giant has a decent guide on this rebuild.

The new Delco r4 has a shorter clutch than the older one in my car. So I'll have to set the spacers differently, or adjust the belt up or down?

Tips/tricks on compressor removal and other things are appreciated before I screw up tomorrow trying. I have the whole weekend to do this though.

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1980 240d
1999 SL500