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Originally Posted by My Schnell
I went through this but skipped ahead … did they say anything about these blocks? Were they running boost, significant track time, what oils were they running, mileage, how they’re driven day-to-day, or anything about how they were used? Just curious if there is more to those blocks’ stories than daily driven #1 bearing failures.
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The video dialogue centers around engineering failure analysis and engineering design regarding the main bearing clearances and oil gallery flow. Here's the A-eye summary of the video:
This video from Brintech Customs explores a significant engine failure issue in the BMW S65 V8 engine (found in the E92 M3), specifically focusing on main bearing failure as a more critical concern than the well-known rod bearing issues.
Key Insights:- The Problem: The workshop has observed a high frequency of engines failing due to the number one main bearing, which can lead to the engine seizing and catastrophic internal damage (0:57 - 1:47).
- Potential Cause: The experts suggest the issue may be linked to the S65’s timing chain arrangement. Unlike the S85 V10 engine, the S65 uses a double-row chain system that may exert excessive upward force on the front of the crankshaft, causing it to lift and make contact with the upper half of the number one main bearing (4:12 - 5:42).
- Consequential Damage: When this bearing fails, it creates friction and heat, causing the bearing to spin in the block. This blocks oil flow, which can subsequently lead to rod bearing failure and further damage, often rendering the engine block scrap (6:20 - 7:27).
Proposed Solutions:- Custom Repair: The workshop has developed a method to salvage affected blocks by machining out the bore and installing custom CNC steel inserts to restore factory tolerances (8:35 - 9:07).
- Preventative Maintenance: To avoid this failure, they recommend that when performing routine rod bearing maintenance, owners should also address the main bearings. They suggest increasing the bearing clearance on the number one main bearing—specifically on the upper half—to provide a buffer against crankshaft movement (11:35 - 12:07).
- Oil Flow Adjustment: They also perform a minor modification to the oil gallery to ensure consistent oil pressure and volume reaching the number one bearing, even when it is also feeding the timing chain lubricators (10:03 - 10:45).
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