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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCH1999 6 speed, 3.4 l, 996 have questions
Leading reported evidence
Check excessive clearance (wear)
Performed · outcome unconfirmed
No successful repair reported for this finding.
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Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed
At the top the camshaft bearings and camshaft bearing journals need to be checked for excessive clearance (wear).
Leading evidence: 'Check excessive clearance (wear)' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'cam unless the journals can be build up' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check excessive clearance (wear)' (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.
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Discussions that performed work without a confirmed outcome
1
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Performed · outcome unconfirmed
Cam lobes, lifter buckets -- excessive play in the bores -- and lifter faces all have to be checked for signs of wear.
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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Performed · outcome unconfirmed
But some DIY'ers have managed though I don't know what they used for bearing clearances.
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Discussions that suspect a cause
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Suspected cause
These do not have inserts so if the cam journals are worn that's probably a new cam unless the journals can be build up with say hard chrome and ground to the correct size.
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Discussions that contain suggestions
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Suggestion
With the engine apart then you should probably check the main/rod journals for wear and if ok possibly fit new bearings.
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
cam unless the journals can be build up
No successful repair reported for this finding.
0
Identified cause
1
Suspected cause
0
Reported fixes
Read evidence and context
Discussions that suspect a cause
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.
Suspected cause
These do not have inserts so if the cam journals are worn that's probably a new cam unless the journals can be build up with say hard chrome and ground to the correct size.
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.
4 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 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: 20261026T165820Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I have 35000km on it just bought it. The motor is running rought, sounds like a knock, and misfire, im taking motor and tranny out. Does any hace an idea on what to order and where, have no history on the car.
Might want to hold off dropping the engine and tranny. The noise could be explained by something that doesn't require an engine out to address.
If you take the engine out you'll you have to identify what's wrong and this requires disassembly. Once you know what's wrong you know what to order.
'course, there is the "while you are there" stuff. With the engine apart then you should probably check the main/rod journals for wear and if ok possibly fit new bearings. (I've done this with other engines but I've never had a Porsche engine apart.)
Good luck finding the acceptable clearances though. Porsche doesn't publish these. But some DIY'ers have managed though I don't know what they used for bearing clearances.
Don't forget the buttons that control crankshaft end play.
At the top the camshaft bearings and camshaft bearing journals need to be checked for excessive clearance (wear). These do not have inserts so if the cam journals are worn that's probably a new cam unless the journals can be build up with say hard chrome and ground to the correct size. If the head/camshaft bearings are oversized I'm not sure what you can do to remedy that situation.
Chain guides might need attention as well as the of course very critical chain guide tensioners.
Cam lobes, lifter buckets -- excessive play in the bores -- and lifter faces all have to be checked for signs of wear.
Might as well consider what you want to do about the IMSB while you are there.
Oh, and there are the cylinder/piston clearances. If any of these are worn the engine may have to have its cylinders sleeved (or whatever the technique is for storing the proper diameter and finish -- I don't think an overbore and oversized pistons/rings are available) and fitted with new rings/pistons.
I have to note the engine is pretty low miles. I've come upon one 996 engine out and apart with low (~20K) miles and the Porsche tech didn't replace anything but the IMS/IMSB and some chain guides that got damaged when the IMSB failed. So there's that.
Still, if you take it apart, it will require new seals. New gaskets. Might as well add a new water pump and new T-Stat. Follow with new spark plugs and what the heck, new coils too.
I love threads that start out with replacing stuff. Why bother with diagnosis? Just jack up the engine serial number and drive a new engine in there. Meh.
A short video or sound clip of the exhaust during startup/idle/rev will get you the best answers.
I recommend you begin with draining the oil and looking in the pan and the folds of the oil filter to see if there are any visible metal or plastic bits. Look for glitter in the oil and consider sending in an oil analysis. High levels of various different metals in your oil can reveal where to look.
This could all help determine just how much "rebuild" your engine will need before you spend a ton of time/money pulling and opening it up.
Also, are you getting a check engine light? If so, consider driving by car parts store who will read codes for you.
This is a source reference. Confirm exact model applicability in the original material.
