The main culprit appears to be a complete bearing system failure, likely caused by an oiling issue.
Here’s what I saw that points to this conclusion:
- Seized Wheels (0:01 & 0:19): You showed that both the "cold side" compressor wheel and the "hot side" turbine wheel are completely stuck. Since they are connected by a single shaft that spins on bearings, this means the entire core of the turbo has failed.
- Oil in the Compressor Housing (0:06): This is the smoking gun. When you remove the pipe, there is a visible pool of engine oil. This means the oil seal on the compressor side has failed, allowing pressurized engine oil from the center housing (CHRA) to be pushed into your intake system.
This type of failure is typically caused by one of three things:
- Oil Starvation: The most common cause. A blockage in the oil feed line, low engine oil pressure, or a faulty oil pump can starve the turbo's high-speed bearings of lubrication, causing them to overheat and seize in seconds.
- Oil Contamination: Debris in the engine oil (like metal particles, dirt, or carbon buildup) can act like sandpaper, destroying the delicate bearings. Always ensure you're using clean, high-quality oil and changing it regularly.
Improper Shutdown (Oil Coking): Shutting off a very hot engine immediately stops the flow of oil to the turbo, but the turbo itself is still incredibly hot. This can "coke" or burn the oil inside the CHRA, leading to sludge buildup that blocks oil passages and causes starvation.
Why Oil is Essential for Ball Bearing Turbos?
While ball bearing turbos have a different internal design, they still rely on a steady flow of clean engine oil for two vital reasons:
- Cooling (The Most Critical Job): This is the number one reason oil is crucial. A turbo's shaft spins at incredibly high speeds (often over 150,000 RPM!), generating immense friction and heat. On top of that, the turbine side is constantly heated by exhaust gases that can exceed 900°C (1650°F). The engine oil's primary job is to circulate through the center housing (CHRA) and carry this destructive heat away from the bearing cartridge. Without oil flow, the bearing assembly will overheat in seconds, causing the precision-engineered components to expand, warp, and ultimately seize solid.
- Lubrication: While they don't float the shaft on a cushion of oil like a journal bearing, the ceramic ball bearings still require a thin film of oil to prevent direct, high-friction contact between the balls and the races they roll in. This lubrication minimizes wear and reduces rotational drag.
So, even a momentary loss of oil pressure at high RPM can be fatal to a ball bearing turbo. The causes remain the same: a blocked oil feed line, a kinked line, a faulty oil pump, or using the wrong size oil restrictor can all lead to the kind of failure you experienced.
When you install your new Kinugawa turbo, ensuring your oil feed system is clean, clear, and providing adequate pressure is the most important step to guarantee a long, powerful life!