How do you replace a tension pulley on a Lincoln 92 town car?

Although I am not familiar with your '92 Lincoln, the answer is pretty well generic to all vehicles. Assuming that new tension/idler pulley is available [in some cases, the entire tensioner arm assembly is sold as a single unit], its replacement is fairly simple. The tensioner arm assembly consists of an "arm," with an idler pulley on one end and a spring loaded pivot on the other end, which is mounted to the engine with a single bolt right through the center of the pivot. IF it is ONLY the idler pulley which requires replacement, then you do not have to remove the tension arm, and the following steps apply. 1. With a "breaker bar handle," and a socket which fits the pully bolt hex head, lever the tension arm just enough to allow removal of the serpentine belt from the idler pulley. This bolt ALSO mounts the idler pulley to the tension arm. Be VERY CAREFUL to draw an ACCURATE diagram of the belt routing over ALL pulleys. Then, if you use string to tie the belt away from the tensioner pulley assembly, BUT firmly attached to all the other pulleys, you can finish the job WITHOUT removing the belt entirely. The other option, if you are knowledgable, or have the guts, is to remove the belt entirely. 2. Then, using the same socket and breaker bar, on the same center mounting bolt in idler pulley, remove the bolt and the pulley. With a replacement pully being available, installation and reassembly is simply a matter of reversing this procedure. As the tension is pre-set, no adjustment is necessary. j3h.