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Planet-9

Engine sounds like it’s about to explode on start up

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10 captured repliesPartial discussion capture · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW

Discussion summary

YOUR RESEARCHEngine sounds like it’s about to explode on start up

Leading reported evidence

Use crankshaft

Performed · outcome unconfirmed

No successful repair reported for this finding.

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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 performed work without a confirmed outcome
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0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

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Performed · outcome unconfirmed

Machine shops says crankshaft is bent and can’t be fixed ...so a good used crankshaft ,replace #3 rod , all bearings ,gaskets ...approximately $2000-2500 in parts and shop fees.

Original post Read captured discussion
Engine sounds like it’s about to explode on start up
Frequently discussed work

Check free

No successful repair reported for this finding.

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Discussions that contain suggestions
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0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion

you never know though, if you're mechanically inclined it's easy to check for FREE.

Original post Read captured discussion
Engine sounds like it’s about to explode on start up
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Leading evidence: 'Use crankshaft' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check free' (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.

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1 matching discussions · 10 captured posts examined · 1 partial discussions

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Check free

Suggestion or failed attempt

No successful repair reported for this finding.

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Reported fixes
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Unsuccessful attempts
1
Discussions
Read evidence and context

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 contain suggestions
1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion

you never know though, if you're mechanically inclined it's easy to check for FREE.

Original post Read captured discussion
Engine sounds like it’s about to explode on start up

Replace with the rpm's

Suggestion or failed attempt

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context

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 contain suggestions
1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion

The more I listen the more I'm confident it's a valve, the key giveaway is the cadence changes with the RPM's.

Original post Read captured discussion
Engine sounds like it’s about to explode on start up
Frequently discussed actions (3)

These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.

Check free

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion

you never know though, if you're mechanically inclined it's easy to check for FREE.

Original post Read captured discussion
Engine sounds like it’s about to explode on start up

Replace with the rpm's

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Suggestion

The more I listen the more I'm confident it's a valve, the key giveaway is the cadence changes with the RPM's.

Original post Read captured discussion
Engine sounds like it’s about to explode on start up

Use crankshaft

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that performed work without a confirmed outcome
1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Performed · outcome unconfirmed

Machine shops says crankshaft is bent and can’t be fixed ...so a good used crankshaft ,replace #3 rod , all bearings ,gaskets ...approximately $2000-2500 in parts and shop fees.

Original post Read captured discussion
Engine sounds like it’s about to explode on start up
Coverage and how to read this overview

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.

10 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.

  • Planet-9: 1 discussions

0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.

0 acknowledgements have no verified action link; they do not establish a repair result.

Generation: 20261026T220748Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources

POST 1Original post

Newbie ....clueless as to what this is caused by. i started the car and thought it was about to explode. I’ve seen many write ups about engine ticking but this can’t be what they are referring to... 2007 Cayman base with no modifications ,no CEL had this experience? Was it timing chain tensioners ? Hydraulic lifters?

POST 2Original post

It sounds like a valve to me, however I can tell you from experience if you have a loose spark plug it will make noises similar to a stuck valve but that's mighty loud for a loose plug. you never know though, if you're mechanically inclined it's easy to check for FREE. Also, make sure your oil level is on spec, it's unlikely to be related but it only takes a second to check. The more I listen the more I'm confident it's a valve, the key giveaway is the cadence changes with the RPM's.

POST 4Original post

it turns out to be a spun con rod bearing on cylinder #3 .

POST 5Original post

Well that sucks. Sounds expensive. What a fix cost?

POST 6Original post

Machine shops says crankshaft is bent and can’t be fixed ...so a good used crankshaft ,replace #3 rod , all bearings ,gaskets ...approximately $2000-2500 in parts and shop fees. labor is free if you do it yourself ...if not $150hr

POST 7Original post

Sorry to hear this. Seems like spun rod bearings and bore scoring in these later engines are becoming more common than the IMS issues in the earlier ones.

POST 8Original post

Spun bearings require a complete tear-down. You need to be well equipped and fearless to tackle this job. I'd do it but then, sometimes fearless is the same thing as stupid!

POST 9Original post

Did the bent crankshaft and spun bearing wallow out the crankshaft journals/bearings? ie - does the shop have confidence they can put in a new crank/bearings and it will have correct alignment and clearances?

POST 10Original post

You might just look for a replacement engine rather than trying to rebuild one that had a bent crankshaft. Seems like a lot of Boxster/Cayman engines are available on various sites due to tendency for these cars to get totaled in front-end collisions.

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