Re: Bad Leak... front main seal?
Replacing the front main seal and water pump on a 258 is pretty straight forward.
Of course you need to remove the belts, hoses, the fan and the fan clutch to get to the water pump. I think the pump takes 4-5 bolts, so just take them off and carefully pry off the old pump. Before you install the new pump make sure that the new pump is made to rotate in the same direction as the old pump.
For the timming chain you need to remove the harmonic balancer. You may or may not need to remove the radiator so you can pull the balancer out. The timming chain cover takes 7-8? bolts on the front and 5 bolts on the bottom where it meets with the oil pan. You might have to loosen all the oil pan bolts in order to separate the oil pan from the timming chain cover. If you do have to drop the oil pan, might as well put a new oil pan gasket. Carefully pry the cover off, clean mating surfaces, drive out the seal, install the new seal, and install.
The water pump and front seal replacement on the 258 is a pretty easy, straight forward process. I say its easy because I helped change the water pump on a few newer Mitsubishis and Toyotas and they are a royal pain to do. You practically need to take half the engine apart.
Hope this helped,