Engine Knocking 1999 Tahoe

It overheated and caused internal engine damage.

When an engine is severely overheated the oil gets very thin, like water, and is ruined. Change your oil and filter immediately! If the knocking persists the bearings in the engine are damaged. Not a cheap fix and, unfortunately, not worth the expense on a vehicle this old. Hope that helps! Jim

I checked all of the symptoms for thrown rods or blown head gaskets or cracked head. For instance no white smoke no bubbles in the water in the radiator no milky substance in the oil cap nor the oil stick no exhaust leak nor sweet smells no coolant smells and its no longer is running hot at all. Its just knocking but the oil idea i havent tried i just added more oil because I've recently had an oil change but will do it again. Any other ideas the motor is also shaking a little harder than usually

You can try a heavier weight oil when you do the oil and filter change but if the knocking continues after the oil change, the damage is done. Without proper lubrication the bearings will grind away against the crankshaft causing excessive clearances between the two. That's why you hear the knocking sound. In a short time you will throw a rod if the knocking continues. Hope that helps! Jim

You continued to drive knowing water pump was bad , now you hear noise from engine . Turn the radio UP so you won’t here it, and it will take care of itself SOON,