06/03/2026
🚨 WHEN A CLUTCH JOB TURNS INTO A NO-START DIAGNOSIS 🚨
This 2016 BMW F80 M3 with a 6-speed manual transmission arrived at Euroenvy on a tow truck with a no-start condition.
The customer had been told the front crank hub may have spun — a serious and expensive problem on the BMW S55 engine.
Fortunately, that wasn't the issue.
When the vehicle arrived, the DME contained the following faults:
⚠️ 160021 Crankshaft Sensor: General Loss of Synchronization
⚠️ 160020 Crankshaft Sensor: Signal Implausible
Both faults pointed toward a crankshaft position signal problem, which naturally raised concerns about a possible spun crank hub.
After diagnosis, we discovered the actual cause was related to a recent clutch and flywheel replacement performed elsewhere.
The flywheel bolts had been tightened so severely that the crankshaft reluctor wheel was crushed and deformed. The bolts required more than DOUBLE the specified release torque to remove. Based on the evidence, it appears an impact gun may have been used during installation.
The reluctor wheel contains the magnetic targets used by the crankshaft position sensor to determine crankshaft position and engine synchronization. Once distorted, the sensor receives incorrect information, causing synchronization faults and preventing the engine from starting.
The result:
❌ No-start condition
❌ DME synchronization faults
❌ Incorrect crankshaft position signals
❌ Crushed and deformed reluctor wheel
❌ Transmission removal required
❌ Flywheel removal required
❌ Additional labor and parts that should never have been necessary
And the surprises didn't stop there.
During disassembly we also found:
❌ Only ONE starter bolt installed
❌ FOUR bellhousing bolts completely missing
These fasteners are critical for proper alignment and support of the transmission and starter assembly. Missing hardware can lead to vibration, misalignment, premature wear, starter engagement issues, and additional failures.
Modern BMWs are engineered with extremely tight tolerances. Every fastener has a specific torque specification, tightening sequence, and installation procedure for a reason. Taking shortcuts or using the wrong tools can turn a routine clutch replacement into a major repair.
At Euroenvy, we don't guess and we don't shortcut procedures. We follow BMW repair instructions, use the proper specialty tools, and verify every fastener is installed and torqued correctly.
This customer was worried about a spun crank hub.
The real problem was a crushed reluctor wheel and workmanship issues from a previous repair.
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