BMW E92 M3 cold-start clunk and anom3’s unresolved follow-up
Anom3’s July 2007-production E92 M3 produced an intermittent metallic clunk on cold starts. Several changes brought subjective improvement, but the owner’s final update says the cause remained unknown.
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A noise confined to cold starts
Anom3 describes a metallic clunk or brief grinding noise on cold starts, sometimes after only a few hours parked. An immediate second start did not reproduce it. The owner identifies the car as an E92 M3 built in July 2007 and later states that it has a six-speed manual gearbox. The reported absence of other performance problems is the owner’s experience, not a diagnosis.
Improvement without a lasting answer
The edited first post records several attempts. After rod-bearing work, replacement of one failed engine mount and a change to the oil-pump-chain tensioner, the owner initially reported that the noise was absent on roughly 75 percent of about 20 starts and quieter on the others. Later entries still report the noise after check-valve and chain-tensioner changes, starter cleaning and other experiments. Those reports do not isolate one cause or establish a general repair procedure.
The lighting theory did not hold up
After two quiet starts with the lights disabled, anom3 briefly considered a connection with a light flash during startup. The owner then reported that the noise had returned and explicitly withdrew that connection. Another member also reported the clunk despite driving with daytime running lights disabled. These posts do not establish a lighting or coding remedy.
A waveform correction and limits of the pressure comparison
Chris719 corrects the description of the recording: it is a time-domain waveform, not a frequency spectrum. Anom3 accepts the correction and uses it to estimate the sound’s timing after ignition. The quoted 90/75/90psi sequence comes from another post and is not a pressure measurement on anom3’s car.
The final update remains unresolved
In the final update, anom3 says the noise continued across roughly 40,000 km of ownership and was still present when the car was passed on. The owner never established its cause and disputes the suggestion that the sound is normal. The owner’s perception that performance and reliability did not change does not prove that similar noises are harmless. Other members’ examples, oil preferences and possible explanations remain separate reports.
A separate member’s VANOS repair report
M3PO reports that BMW replaced VANOS gears under the regular warranty and that the sound had not returned about 30,000 miles later. This is a separate car’s attributed outcome. Anom3’s check valves were only scheduled here; BPMSport separately reports that changing them altered but did not eliminate his noise. None establishes a repair for anom3’s car. The shared dealer repair-order pages record a right-side timing-chain tensioner change that did not remove the noise, followed by replacement of the bank 1–4 inlet and outlet VANOS adjustment units. A later start test is described as quiet. A separate coolant-hose leak on the paperwork is not the reported cause of the rattle.
The noise was also reported before tuning
The suggestion that the noise occurred only on tuned cars is contradicted by several members’ stock-car reports. Anom3 says the noise predated a tune installed seven days earlier. These accounts do not establish general tuning safety or one cause.
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