Reader Question Had oil changed in a 2000 Yukon (147,000 Miles) by a dealership. Around the time that the new oil change was required (150,000 Miles about 3000 miles on the oil) the engine started to make a terrible knocking/whining noise with no check engine light.
When I took the vehicle into the shop, it showed that the oil was overfilled by about 2 inches over the full mark. Is it possible for an engine to hold that much oil over a 3000 mile period without blowing it out? Also, could the oil being overfilled cause this engine noise that I am hearing? If it can, what would be the most likely cause of the noise?
The shop where the vehicle is at, is telling me that they will have to take off the head to see where it is coming from because they have no idea what is making the noise, and they believe that it is under the head. Do you have any suggestions?
Hey there Luke,
This is going to be a tough call as to what really happened. It is possible for the engine to be overfilled by that amount and not blow out the excess oil somewhere. I would say that there is a 50% chance that the excess oil caused your engine noise/knock.
What tends to happen when there is excess oil inside the engine block is the oil becomes agitated and foams up, causing the oil pump to suck up foamed oil/air and not the true liquid oil that is should suck up and pump through out the engine.
So, basically what happens is the engine runs out of oil since the pump is not pumping the oil in liquid form…..the engine runs out of oil pressure and internal damage occurs.
So, will removing the cylinder heads uncover the damage? IF the engine really did run out of oil pressure the damage will probably be located at the bottom of the engine like in the rod bearings, crank bearings, crank shaft, pistons etc. etc.
Removing the top part of the engine (the heads) will probably not reveal a lot of information and will probably just waste your time and money. If the bottom of the engine is damaged, replacing the engine probably makes more sense with 150,000 miles than trying to overhaul this engine.