'87 4kq: what's this hose?

[Andrew Buc]

While changing my oil today, I noticed a hose connecting two components
fairly low in the right front of the engine compartment. It's about 2
or 2.5" in diameter and forms a quarter-circle in a lateral plane. I
bring this up because the hose isn't in v. good shape. What system is
it part of, and what would be the consequences if it let go? Anyone got
a P/N? Thanks!