I have a 2005 Toyota HiLux with an AD4D engine; over the last year it has a diesel knock (especially when it is cold, until engine warms up). I have changed injectors, changed the timing belt and tensioners. Yet, it still has the same diesel knock when cold, any suggestions?
A number of vehicles of your vintage using that engine suffered from a lack of oil pressure due to accumulated contamination on the oil pickup. Remove the oil drain plug and inspect the oil pickup and make sure it isn’t clogged up with accumulated crud that could affect the oil pressure.