We can’t take credit for this idea. It’s been floating around the internet for some time now, which is where we saw it, but it’s worth passing along. Strap wrenches are great for helping to remove a stubborn oil filter or can be used to hold smooth round components like a serpentine water or power steering pump pulley. Typically, they are used on anything round that is A- larger than you can fit a set of pliers on or B- needs to leave the gripping surface undamaged. The trick of finding a good strap wrench is getting one that can exert enough force on the strap to reliably grip and overcome fastening torque, without marring the surface you’re gripping.

To make this simple tool, You’ll need a length of 6-rib serpentine belt — it doesn’t need to be new, a discarded belt is fine. Simply thread the belt through a large 1-1/4-inch box-end wrench. Wrap the loop of the strap around the oil filter and then use the box end wrench as a lever with the ends of the strap pinched between the wrench and filter.

If you want to add more grip than the 6-rib belt offers, use a slightly wider belt. An 8-rib belt, with an appropriately larger box-end wrench, will offer more purchase on the item you’re wrenching on. This homemade tool works much better than the plastic strap wrenches we’ve purchased in the past, because there’s more leverage with the larger wrench. This is now our new favorite tool.

A homemade strap wrench is about the simplest tool to make and use. Trim a length of old serpentine belt and wrap it around the oil filter. Loop the strap through the box end of a large end wrench and then use the wrench to loosen the oil filter.