Wrenchin’ Wednesday: The toilet paper wormhole

Some steps in a project, though innocent and trivial, produce disproportionately disastrous consequences if done incorrectly. Anyone who’s opened up their engine while it’s still resting between the fenders knows the risk of dropping something down into the motor—a momentary slip that may require hours of painful disassembly.

Today’s Wrenchin’ Wednesday comes from the 6.5-liter Detroit/General Motors diesel community, which has invented a trick safety net for replacing the injection pump that has uses in dozens of other projects. Toilet paper rolls, when they’re not wiping your rear, are apparently saving it.

The injection pump must be separated from the timing gear that spins it during replacement. There are two ways to access the timing gear’s three bolts: Strip down the accessory drive and waste a bunch of coolant to access the massive timing cover, or simply remove the oil filler neck and bar the engine over by hand to rotate the bolts into the access hole left behind the filler neck. The catch? To save 2–3 hours of extra work, you risk dropping three bolts into the timing gears during removal and install … which would put you back at stripping off the timing cover or, worse, lifting the motor to get at the oil pan. You can guide the bolt out on the socket with an extra finger, but who doesn’t like a little extra insurance?

The toilet paper trick basically encapsulates the area through which you’ll be pulling the bolt. If the bolt does fall out of the socket, it will fall into the cardboard tunnel we’ve just inserted into the timing cover’s access hole. The toilet paper roll is cut to length so that it easily protrudes from the cover, preventing it from falling into the cover or letting the bolt get caught by the back-lip of the access hole. The slit is cut length-wise to allow the roll to slide into itself to fit the diameter of the hole. Real simple, yes—but real effective at safely teleporting a socket and bolt through the oily cosmos of motor.

Will you ever need to rely on the toilet paper tube? Hopefully not—but when you feel that drop in your stomach as, eventually, one bolt does head for the abyss, you’ll be relieved to hear it bounce off the inside of a toilet paper roll rather than clink down into the motor like a sadistic pachinko ball.