1987 2.6 4x4 auto transmission
My oil pressure has decreased. Oil light comes on when oil is heated up at idle. Later temperature goes up. Will overheat if continue to run. I changed thermostat and water pump. Still heats up but not as quick. I tooktruck to mechanic to fix. I want to change oil pump. Seems like big job. They said preventative maintenance on timing chain is not required but oil pump is probably problem and they will replace. Anything else I should replace while oil pump is replaced? Should I have timing chain replaced? I do not think timing chain has Ben replaced andtruck is nearly 200k miles.