swim's been having problems with a vacuum pump (2 stage rotary vane, SV-140) as of late and is on the border of replacing it. if the pump can be repaired, swim will try, but a suggestion like "the pump is fucked" will prompt swim to obtain another pump. the pump troubles are due entirely to swim, as poor judgement was exercised when stripping solvents (DCM in particular).
the pump had pulled about 600 mL of DCM (total) through it, and was not pulling anywhere near the maximum vacuum of .5 mmHg achieved earlier, it was pulling ~1.6 mmHg. this was unacceptable for a vacuum distillation that had product coming over at 90°C and .2 mmHg (swim's hotplate can't generate enough heat, and i'm not using an acetylene torch), so swim thought it would be a good idea to disassemble the pump and clean it out (oil that emerged was brown and contaminated).
disassembly went easily enough, but upon reassembly there were clicking sounds when the pump was turned on and a successive oil draining showed the oil to be brown and very much contaminated again. re-disassembly demonstrated that the vanes were inserted improperly (swim's bad) a.k.a. backwards (curved edge inward, towards shaft). once the vanes were properly seated, the pump ran OK for a few hours, enough to get through another distill (no solvent pulling this time). it was noted that the maximum vacuum attained was ~5 mmHg, which is, again, unacceptable.
a third disassembly was done and everything reassembled after degreasing and a wipe-down with acetone-soaked paper towels (cleaning was done in a more limited scope on earlier disassemblies). the vanes were inserted properly and it had the clicking problem again. this is where things stand, and unless swim can diagnose the vacuum pump problem, another must be purchased.
another option is to send it back to the manufacturer to service it, but this option must be investigated. the oil that comes out of the thing is always brownish and i suspect it has something to do with the carbon (i think they're carbon...) vanes. it is also to be noted that swim didn't have a torque wrench available to restore all original bolts to a specified torque, but is this really that important for a small vacuum pump? also, should swim try replacing the vanes and gaskets?
for the record, swim already read the definitive post on vacuum pump overhauls (starts w/ post No 244556) and swim followed nearly all the suggestions contained therein. the only thing swim didn't try was replacement of the vanes, and that could be just what is responsible for the clicking, especially after the initially improper installation.
thx for reading