89 Montero V6 With a Seized (?) Engine Help
 

Hey y'all.
I just bought myself a no-start '89 Montero with the good ol' 3.0 V6 in it. Problem is, when the you go to crank it, the starter engages, spins, but does not spin the engine. I realize now that I should have done this pre-purchase, but I put a socket on the crank pulley, and it will spin for about ~120 degrees and then stop HARD. I was under the impression that these first gen 6G72's were not interference engines, but I'm finding conflicting data. Either way, my engine will not spin. The previous owner replaced the timing belt, then drove it for a week after which it promptly died. I am a pretty skilled mechanic, but these platforms are new to me, so any help would be greatly appreciated. Thanks!

At this point I'd stop trying to start it and pull the thing between coves off and exaine condition of the belt and going alingment. See what is going on first, then decide on the appropriate course of action

I get you. Really all I need to know is wether or not the engine is interference or not.

Some years ago I neglected to replace the timing belt of my 1990 Montero when I should have and it broke, shortly after 120,000 miles. I needed a complete cylinder head rebuild as some valves were bent. So, yes. The V6 engine "is interference", if I understand correctly the meaning of the term. It is no accident that Mitsubishi requires a new timing belt every 60,000 miles. Most likely you need to rebuild the cylinder heads.

How much did it end up costing you to do this? where did you source new valves from? and were the heads themselves damaged or just the valves?

When the timing belt broke, instant stall. I barely had time to coast to a stop, luckily not too far from the local AAA shop so that's where I towed it. It cost $2636.22 in 2016. They sent the heads to a machine shop that did the actual rebuild job. They changed the water pump and tensioner along with head gaskets, cylinder head bolts and whatever else is standard for that kind of job. They probably got a standard head rebuild kit. Most likely the heads themselves were not damaged but the machine shop did the job, so I can't say for sure.

Yes, the 6G72 SOHC is an interference engine. I bought my 98 Sport(has the same exact engine) with the same issue as yours. Previous owner changed timing belt and did not set the eccentric tensioner correctly. Pulled the heads and found multiple bent valves, pulled heads off a junker, had em shaved, and slapped em on the block with new head gaskets and re-did the timing belt and components myself. That engine went another 100K miles before it started spitting glitter.