R4 compressors (yours) are notorious for shaft seal leaks. Use a double lipped seal. Special tools from Autozone are free loaners for the job.

If you do get a compressor, try to get a new one, as many of the chain store rebuilts R4's are suitable as anchors for a skiff.

__________________
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)