Knocking on engine

[C Houston36]

Good Afternoon 

I have a 94 Hilux surf with the kz1 engine.  The engine starts and runs but once it's warm up to running temp it begins to knock and lose oil pressure. 

It's not main bearings and con rods

 

What could it be? Your help would be greatly appreciated. 

[Bper]

Hi Charlotte, based on what you’re describing, it sounds like the most likely issue is with the oil pump or possibly the oil pressure relief valve. When the engine warms up, the oil thins out, and if the pump’s worn, it might struggle to keep the oil pressure up.

It could also be that the relief valve is stuck open, which would cause a big drop in pressure once the oil heats up. The knocking noise could be down to some engine parts not getting enough oil.

Since you've already ruled out the main bearings and con rods, I’d definitely start by checking the oil pump and doing an oil pressure test to see what's going on.👍

[C Houston36]

Thank you for your reply. We will look into those suggestions. 

[flash22]

Has it had an oil and filter change with the correct oil? has the oil pressure been checked with a manual gauge