BMW M52 Broken Camshaft
Here’s a disheartening one; from a 1999 BMW 328i. This car had only 160,000 miles on it. Engine failure like this should not happen. BMW’s 6-cylinder engines can last a lot longer than this one did.
The car came in as a rough running / no start condition. After checking basics (fuel pressure, engine codes, etc) we ran a compression test on the engine. It revealed good numbers in the first 3 cylinders and zero (!) compression in the last 3. We got the client’s authorization to diagnose further and we did a leak-down test in those last three cylinders. Next we used a bore scope to view the valves from inside the combustion chamber. We could see that the intake valves were not opening or closing so we suspected a broken camshaft.
We removed the valve cover to look at the valve train and found significant oil sludge. Turning the engine confirmed our fears: The intake camshaft was snapped and the last three cylinders did not have intake valve movement.
This is a classic case of death-by-neglect. This BMW should have had a lot more life in it but due to poor engine oil services the engine sludged, the valve train was compromised for lubrication, and the camshaft snapped. Unfortunately this engine is not worth fixing. To fix it correctly would require complete dis assembly of the entire engine to clean all of the sludge. Net result: this car is probably heading to a junk-yard. What a shame.