There is no time frame for replacing a relay. You will only need to replace one if it goes bad. Then you can test it by replacing it with a different relay from a different plug that is the same type, and that you check to see what that one will affect. hope this helps.
already have it loose
Yes, only if they have the same engine.
Best bet is to replace the radiator.
Remove and bring to radiator repair shop or replace at 1-800Radiator
yes
You need to replace the thermostat and flush the system of crud.
how to change radiator 1995 jeep grand Cherokee Laredo
Yes
How do I replace water pump on 2004 jeep grand Cherokee
The thermostat on a 1996 Jeep Grand Cherokee 5.2L is replaced by draining the coolant and disconnecting the radiator hose. The housing is then unbolted, the thermostat removed, and a new unit put in its place.
Should be a plug either at the bottom or rear of radiator
on my 2000 grand Cherokee Laredo is under the passenger head light is hard to get to is a Little black box w. 2 screws on it hope the helps..