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YOUR RESEARCHParanoia strikes...
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Replace (under the 8 yr/80k mile warranty
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Read evidence and context
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Performed · outcome unconfirmed
I've had both CATS replaced (under the 8 yr/80k mile warranty on emmision equipment) in the last 2 months.
Leading evidence: 'Replace (under the 8 yr/80k mile warranty' (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.
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Suggestion
it's a simple fix - relatively inexpensive - and gets you new belt as well as pulleys check for free.
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Suggestion
Just replace the cam and check the tappet buckets.
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Suggestion
about catalytic converter, check my videos, I made 3 of them when I had my cat converter problem and indeed a few weeks later the CEL light came up and the dealer replaced them under warranty as well
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Suggestion
about catalytic converter, check my videos, I made 3 of them when I had my cat converter problem and indeed a few weeks later the CEL light came up and the dealer replaced them under warranty as well
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So, over the past couple of days my engine has been making some noise that is not particularly confidence inspiring. I had been convincing myself that it was all in my head, but today my wife declared that my car sounded like crap. That is clearly a bad sign. The first fear that strikes any 996 owner is obviously IMS, but I'm hoping for some better news...
I took a quick iPhone recording of it:
For the time being, it's sitting in my parents' driveway (I was at their house for dinner) awaiting a tow in the morning to a location TBD.
Any thoughts?
Whatever it is,it does not sound happy. I woul definately not run it until it's determined what's making the noise. It could be a lot of things from serious, IMS or rod bearing,to less serious but still expensive like maybe something broken in clutch. If it's internal though,running it will do a lot of damage. Just my .02. good luck
Many of those first 1966 3.8L Pontiac overhead cam straight sixes had soft cam lobes that wore out prematurely and sounded like that. Did you notice rough idle and loss of power pulling a hill. Just replace the cam and check the tappet buckets.
If this was a Porsche there was a lister recently that had a similar noise in his 996. All including Mr Raby suspected IMSB. It was "clutch fingers". Good luck.
No noise is a good noise. Why in the world do people continue driving these cars AFTER they hear noises?? More cars are driven to death than anything else.
I simply do not understand it.. Its like thinking you are having a Heart Attack, but instead of resting and calling for help you decide to see how fast you can do a hundred yard dash.
Lots of noises aren't as bad as they sound but you must assume the worst case scenario and hope for the best. I simply do not understand. Hearing a noise? STOP!
That noise in the video sounds lore like a water pump to me than anything else, BUT you have to assume its the IMS and prove that it is not. Don't run the engine any more at all and get it into the hands of someone who has seen these failures and has common sense and a clue. Don't even let them start it to diagnose it without pulling the sump plate first.
Videos isn't good at all for diagnosing the pitchs and tones of these failures.
The reason, at least in my case, is that the noise got progressively worse and as soon as it was severe enough for me to conclude that it really was abnormal, I shut it down.
The sound is being magnified by having the mic right up next to the engine. From the cockpit, it's a barely discernable noise. If I'm sitting in traffic with the top down, I can't hear it.
If I actually follow the "Hearing a noise? STOP!" mantra, I wouldn't ever be able to drive. It's a car. It makes noise. The question is what noise is normal and what noise is not.
Thats the whole thing.. If you have ANY new noise it is NOT a good noise. This is why its very important to pay attention to the engine and understand whats "normal". Doing this helps you note the abnormal noises much more quickly.
I can't think of any instance where an abnormal sound increased performance or longevity. It may be a car engine, but it should not make noises. Any noise must be looked into and you can't waste any time at all. The majority of the engines that we see that we can't save could have been saved if the driver had simply shut them down and not fired them back up until we could look at them.
Collateral damage and foreign object debris doesn't play.
I wouldn't restart it so we can listen to it with a scope, how ridiculous. I'd just bring it in before starting it again, that's not a normal sound, for now that's all we know. Best of luck on this one.
Take a rubber mallet and hit the catalytic converters. If one (or both) sound like something is loose and rattling about inside that may be your issue. I've had both CATS replaced (under the 8 yr/80k mile warranty on emmision equipment) in the last 2 months. If your 996 still falls under the warranty the dealer won't replace it until a CEL (for catalytic efficiency) is illuminated. On the second CAT I had to drive around for three weeks after the rattling started until the CEL finally went on.
Good luck!
about catalytic converter, check my videos, I made 3 of them when I had my cat converter problem and indeed a few weeks later the CEL light came up and the dealer replaced them under warranty as well
the noise is scary at first:
You Tube
after 15 warm up at idle:
You Tube
after 15 minute drive:
You Tube
glad it worked out. it's a simple fix - relatively inexpensive - and gets you new belt as well as pulleys check for free. as a side note for cats - given cores size - one has to warm the car up and avoid cold shutdown and restart (ie 5min drive from cold then stop for hour then again 5min drive from cold etc). it is the n1 cause of cats cells failure in 911s.
This is a source reference. Confirm exact model applicability in the original material.
