I managed to round off the oil sump plug after I snapped a water pump pliers combination wrench and a ratchet.

how do I take off the plug? Should I just buy a new oil pan?

If I recall the plug is steel. This will allow you to weld on a nut onto it. If the plug is aluminum like the pan you can still weld something onto it just not as EZ.

Remember to disconnect the battery before doing any welding on a car.

A small stilson wrench?

Use Vice-grips (a locking wrench) to remove the drain bolt, and replace with a new bolt and washer - and do not over tighten!

Yeah the biggest one please!


The plug was definitely overtorqued by the previous owner. I'm considering taking the engine out because the sump is leaking anyway and I am concerned about the state of the right chain tensioner.

Sorry to hear of your woes.


Other options are locking wheelnut/stud removers which cut a left hand thread as they tighten on or hitting a slightly undersize socket on; I can understand this being a last resort as you could dent your sump.
Search: 11pc Twist Sockets Locking Wheel Nut Remover Non Slip Broken Studs Rounded Bolts
or
Brand New Locking Wheel Nut Remover Car Key Damaged Alloy Wheels Emergency Tools


Good luck,


Mike.

I wasn't joking about the stilson, but a small one about 12" would work or a judicious blow with a hammer and chisel might work.
I don't have any confidence in screw extractors based on experience.

the 18 inch stilson did it! Somebody put some kind of glue as a sealant!

Changed the oil so I can test if the rattling is still there on startup then I'll be changing the oil pan gasket.