8 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHnoise on start up 996
Reported or suspected cause
damaged catalytic convertor
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
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 report identifying 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.
Reported cause
this may be random but i had a similar sounding problem on another car (not a porsche) and mine turned out to be a damaged catalytic convertor.
Leading evidence: 'damaged catalytic convertor' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'damaged catalytic convertor' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Tighten (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.
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
My local indy diagnosis after inspection: heat shield bolt needed tightening (free).
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.
8 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
911uk: 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: 20261026T144035Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I have a 02 c4 cab and intermittently when I start it up there is a loud rattle /banging noise from around the exhaust area a bit like bricks in a cement mixer!! not very nice. This lasts around 3-5 seconds and then stops altogether. I had new rear boxes put on last week but the sound is still there. When its at the garage however it is hard to get it to happen - sods law! so becoming difficuly to identify. Any thoughts on what this might be?
its can be cold or warm, even if left for 30 minutes sometimes it will happen, and other times when cold it won't though its a pretty dead cert every morning on first start. It seems to be coming from the exhaust though hard to tell. It isnt a tappety rattle.... ihave read a 997 thread about the same which said it could be an auxhillary air pump:?:
this may be random but i had a similar sounding problem on another car (not a porsche) and mine turned out to be a damaged catalytic convertor. Has there been any loss in performance ?
Damaged Cat sounds to be a strong possibility as already suggested.
Whats the start up oil pressure like ie up to 5 bar once fired up?
Regards Big Bob :bye:
Jakeh i too had a rattling exhaust and was told that it was one of my catalytic converters. Hoever, recently my water pump went and needed to be changed. While doing so, my mechanic notied that a bracket plate on the exhaust had cracked (common occurance apparently) and was no longer oing what it should do. The mechanic moved the clamps inward to negate the crack and now the rattling has stopped and saved me $$$ on a replacement cat.
I'd suggest getting the car up on a ramp and have a good knock around the exhaust area before buying any replacement items!
Taran :thumb:
I concur. I had a rattling from the exhaust area. OPC Chiswick diagnosis after inspection: new heat shields needed (c.£70 parts, 1hr labour). My local indy diagnosis after inspection: heat shield bolt needed tightening (free).
FYI - it seems that heat shields are a common cause of rattles. I dont know if its the fixing bolts that corrode, or the shields themselves, but its common. And just in case this is all new to you, the heat shield looks like a large piece of thick kitchen foil and sits around the bum of the car (rear bumper & arches & exhausts)
This is a source reference. Confirm exact model applicability in the original material.
