I just bought a 1990 Montero Lwb. It is a 6 cylinder automatic. It has 179000 miles. I have been reading all that I can find on it. I have a few plans for it. I basically want to have something to tow my 16ft bass boat and use for camping. I plan on some bigger tires and a roof rack. It has a unique spare tire.
Nice color.
For bigger tires, 32x11.5 usually fit w/out modifications although it's possible a slight torsion bar crank will be needed depending on your suspension sag. Additionally, the tires may wear down the rubber bumper end caps slightly (1/32-1/16") during turns but nothing to really worry about.
If needed, you may want to upgrade the rear end and install one from an 89-91 LS montero (for a limited slip in back) or one from a 94-96 SR montero (for a locking rear end in back). Otherwise based on your usage, it should be the perfect rig.
Wear items include the valve guide seals. Once worn out you'll notice oily smoke immediately during a cold start and after warming up but no power loss (as happens when the rings go south). The fix is as simple as replacing just the seals or if you have extra time & money doing a full valve job.
Since it's new, I'd be sure and do a full fluid check. For the transmission, a full flush works really well and gets rid of the extra fluid in the torque converter. Just be sure you use 100% compatible fluid. If you dont you will ruin your transmission in short order. Both Mitsu and Hyundai fluids work in this transmission although I'm not 100% sure if there's more than one type of Hyundai fluid available. Mitsu's more expensive but the fluid change is so infrequent it would be penny wise pound foolish not to use it if you have access to it.
HTH.
