Hey guys im looking to buy an 87 xj and its got 121k on it and I know thats nothing for a 4.0 but I want to know what maintenance should have been done at 100k so I can ask the owner if it was done. Thanks

 

Definitely ask about the cooling system. If nothing has been done to more than changing coolant the system should be replaced. You're in the $300 range if you do it yourself.

 

Complete tuneup, trans and transfer case fluids changed, along with axles.
Lube and oil change. Air filter replacement.

 

Yeah full tuneup would be almost required.

Ignition (Plugs, Wires, Cap + Rotor)
Cooling (Full flush, new thermostat, new hoses, new radiator cap).
New serp belt, air filter, thoroughly clean throttle body.

Engine oil, Brake fluid, power steering fluid, transfer case fluid, differential fluid, and blinker fluid should all be swapped as well.

Suspension - you may want to look at your tie-rod-ends and see if anything is super worn out (depending on driving habits). Ditto for ball-joints and muffler bearings but they usually last much longer.

 

I wouldn't trust him if he told me he did and would redo it all anyway.