i have an 87 325e and when i turn the key to start it, all it does is click once? the battery is good. could it be my starter?

...yes well you are not getting the Cold Cranking Amps to the Chassis and to the engine...what you need to do is break out a coarse wirebrush and scrub the end of the 1/0 black battery cable what connects to the frame with the wirebrush and the frame/chassis where the thing bolts to...this way you can pull the 300 cold cranking amps needed for your startermotor...on a side note batteries will degrade ten percent per year...get a New battery...period~

there is a 1/0 meaty cable going to the engine block as well (where the startermotor resides) is connected to the frame on one end and to the engine on the other end...this is the one that needs to pull the big amps~