Ok I'm going to look at a 89 4runner it has 300k on the chassis and the top end has been rebuilt but I'm curious on how long the bottom ends on these motors last ? I also realize this will be different on how it was abused just need a general thought thanks

 

I've seen them last for over 300k! But if the top end was redone its most likely because the timing guides wore out and broke off and the chain rubbed a hole in the timing cover which cause coolant to get into the bottom end! I'd be kinda Leary about that part! But if you crank it up when it's cold and it doesn't rattle like hell then it's probably not too bad, or smoke while its running! They're tough engines and can handle their fair share of abuse but heat and prolonged high rpms are killers to them!