15 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHengine crank failure
Leading reported evidence
Run like crap
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
Unsuccessful attempts
1
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Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed
At first we thought it had thrown an alternator belt (which it did), but after putting the new belt on, it still ran like crap.
Leading evidence: 'Run like crap' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'good reason not' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Run like crap' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that suspect a cause
1
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Suspected cause
Probably a good reason not to lug the motor with the lightweight flywheel.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
15 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261026T112012Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Definitely an air-cooled crank with the gear-driven IMS and bronze distributor gear.
Something had to be wrong to break one, not just from power I'd assume.
Shoot, Tippy, I was hoping to stir some 996'ers emotions by posting this on here and adding to the "996 crappy-engine-hysteria"!! It's from my friend's 3.2L - surprisingly it still ran, with less power and made a lot of noise.
That's more common than you think...
FYI... I was in the car when that happened. We were able to drive back to the pits and onto a trailer!! At first we thought it had thrown an alternator belt (which it did), but after putting the new belt on, it still ran like crap.
One of the things I like to think a proper warm up period and cruise helps prevent. Ugly stuff. Not sure if the bearing spun before or after the break.
I wonder if the case flexing could of started that.
I wonder if it is always between #3&4? Harmonics? Case flex? That is why the race teams keep track of hours on different componants. Finite life on everything at max stress.
Haha, its ok, yours should be fine. I'm in the same boat but making over 2 times the factory HP. But remember, the 3.2L crank is the same as the 930 crank so they can take some serious hp/tq.
Vibration or oil starvation may of killed these two cranks above.
I saw a write-up by Jake Raby that said all the broken cranks he had seen on M96/M97 engines were on cars with light weight flywheels. Not sure the statistics on this, but it was interesting. He seemed to think that the dual mass flywheels helped with the harmonic balance. Thought it was an interesting observation.
