I've had my '89 4.2 now for 5 years. When I bought it had 178,000, its at 201,000 now. Well in the last year I have had to replace the thermostat and water pump, and now it's giving my a large amount of blowback smoke from the Valve cover. I also found traces of water on the dipstick but that was before I reinstalled the thermostat. Pretty sure its time to go at the engine. I am looking for advice on the experience out there on weather to rebuild of replace the engine.