Mitsubishi Repair: overheating,waterpump and timing, crankshaft pulley, worst case scenario

Question
i own a 1991 mitsubishi v6 magna TR .. i think its a 2.5 or something? not sure on that .. it had some overheating problems, where water was leaking out and eventually overheated that badly it melted the timing belt. the problem turned out to be the water pump needed replacing, but we found out too late. we've just installed a new timing belt but we cant seem to get the bottom crankshaft pulley to do a full revolution .. it always stops one notch away from the timing mark, could this mean theres a problem with the valves? all seem to be fine and working ok .. or could it just be the timing marks are off?

Answer
Mel,
The Magna was not a model sold in the US, so I have little information about it.  But if it's like most other Mitsubishis, it uses an interference engine.  That means that the cylinders can occupy the same area as the valves.  The only thing keeping the two items from smashing into each other is the timing belt.  With the timing set properly, the cylinders and valves never touch each other.  But if your timing belt broke when your running at high enough RPMs, odds are one or more of your valves could have gotten bent.  Also, your timing belt wraps around the oil pump as well.  Since your engine first overheated because the coolant stopped flowing, the timing belt broke, and that means the oil pump stopped pumping as well.  No oil and high heat can result in melting internal engine parts.  That would be the worst-case scenario, but its possible.

The crank can be turned easier if your spark plugs are removed, so if you have not removed them, take them out and see if it's easier to turn the crankshaft.  You'll want to be sure the #1 cylinder is at TDC and all the timing marks are set before proceeding with replacing the timing belt.
Good luck!