I just read this evening about a recall dealing with that very thing. Here is a description taken from intellichoice.com
ENGINE AND ENGINE COOLING:ENGINE
Manufacturer Recall Number00V311001
Model AffectedMONTERO SPORT
DefectVEHICLE DESCRIPTION: PASSENGER VEHICLES: MIRAGE MODEL VEHICLESEQUIPPED WITH 1.5L ENGINES; MONTERO SPORT MODELS EQUIPPED WITH 3.0LENGINES; AND MONTERO MODELS EQUIPPED WITH 3.0L ENGINES. THE BOLTSECURING THE CRANKSHAFT PULLEY CAN BECOME LOOSE AND THE PULLEY COULDFALL OFF THE VEHICLE.
ConsequencesTHE CONDITION CAN RESULT IN A LOSS OF POWER STEERING ASSIST, INCREASING THE RISK OF A CRASH.
Corrective ActionON THE MIRAGE VEHICLES, THE DEALERS WILL INSTALL A NEW, IMPROVEDCRANKSHAFT PULLEY BOLT ON THE OLDER ENGINES. ON NEW ENGINES WHICHALREADY HAVE THE IMPROVED BOLT, THE DEALER WILL TIGHTEN THE CRANKSHAFTPULLEY BOLT TO THE CORRECT TORQUE SPECIFICATION. ON THE MONTERO MODELS,DEALERS WILL TIGHTEN THE CRANKSHAFT PULLEY BOLT TO THE CORRECT TORQUESPECIFICATIONS. IF THE BOLT IS DAMAGED, IT WILL BE REPLACED.
NotesOWNERS WHO DO NOT RECEIVE THE FREE REMEDY WITHIN A REASONABLE TIME SHOULD CONTACT THE MANUFACTURER.
That being said, there is no reason the dealer should have needed to fiddle with the crank pulley to do the cam plug seals. I have to replace mine also, and from all the info I have read to prepair for it, its rather straight forword and simple to do as attested by this answer to FAQ's from this page about 3/4 the way near the bottom:
Since you have had the truck since new, do you recall having this recall service performed? If it wasn't, hey, you might have a strong case to have Mitsubishi pick up the tab for repairs. It may even be possiblewell that the tech attempted to perform the recall and screwed up. In any case, I would be doing some Googling into this known issue, starting' with the Mitsubishi Montero Sport forum FAQ's referenced in the above link, and this owners forum as well:
Both have a great wealth of info about our babys. Hope my long rambling helps in some way. God bless, and good luck with your issue.
Dave B. in PA