The Lazy Mechanic’s Guide to Changing a Serpentine Belt

In this case, my 2002 Jaguar XJR 100 needed a new supercharger belt. Jaguar’s shop manual lays out the replacement process in minute detail, complete with pictures. But the manual recommends draining the coolant and removing the entire fan assembly to gain access to the belts and pulleys. That, simply put, will not do for us. Hey, it’s not like we have to get both elbows down there to replace the idler pulley. (Actually, we do eventually have to do that, but that’ll be on another episode in which we remove the fan assembly for better access to the innards.)

Naturally, we got some great advice from the denizens of JaguarForums.com, where several members had replaced the belts on their X308 XJs without draining the coolant, removing the fan, and performing all the other mechanical wrestling moves the manual recommends. They did it by putting the forward-tilt hood in the “service position” for a little extra room, and then removing the belt by using a flat tensioner bar (one with a 1/2-inch drive) to slacken the belt and fumbling around a little down there.

The main problem with this method is the lack of clearance behind the tensioner pulley—a space just enough to slide the belt through, but without any extra margin. To guide the belt into and out of its engagement position, you have to turn it almost perpendicular to the pulley. 

Once you get it through the space, however, you're home free. And so, we went on eBay Motors and bought a new belt (one with an alligator pattern on the drive side, which is said to prevent slipping) and a tensioner bar. Then, we went down to The Drive Garage, turned the cameras on, and made this video.

Laziness may not be a virtue, but it can spark creativity, swearing, and first-degree burns.