318 oil leak
Depending on the year of your 318 (or the year of your timing cover, anyway...) you would need to pull the whole front end off your motor to replace the seal (as Shig outlined above), but before you do that, just take the balancer off and inspect the seal area- early teeners had to be disassembled to replace the seal, but later motors (mid to late eighties? Not sure of exact year) went to a cover that installs the seal from the outside, meaning you don't have to do the whole disassembly thing- just something that takes a minute to check and could save you a bunch of time.
Old style:
New style:
Depending on the year of your 318 (or the year of your timing cover, anyway...) you would need to pull the whole front end off your motor to replace the seal (as Shig outlined above), but before you do that, just take the balancer off and inspect the seal area- early teeners had to be disassembled to replace the seal, but later motors (mid to late eighties? Not sure of exact year) went to a cover that installs the seal from the outside, meaning you don't have to do the whole disassembly thing- just something that takes a minute to check and could save you a bunch of time.
Old style:
New style: