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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHName that sound... bad cat, or IMSB failing...?
Leading reported evidence
Check cats an mufflers
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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Suggestion
In that case, you will be limited to just checking the cats an mufflers with the mechanical stethoscope or a long screwdriver then.
Leading evidence: 'Check cats an mufflers' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check cats an mufflers' (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
If you can get the rear up, you can check the IMS area and the cam cover.
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Suggestion
On the lift before you start the engine you can pull the oil filter housing and dump the contents out into a clean pan.
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Suggestion
Fluid lubricates the internal gears, gears aren't moving when car is standing still.
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Suggestion
I would change the fluid if it is due, or the fluid's change by date is in question, or the fluid may not be the right fluid and one wants to get back on track in this regard, and if the rattle is diminished afterwards that's just a bonus.
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Suggestion
I would change the fluid if it is due, or the fluid's change by date is in question, or the fluid may not be the right fluid and one wants to get back on track in this regard, and if the rattle is diminished afterwards that's just a bonus.
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Suggestion
Coming up to a stop concurrent with bringing the car to a standstill I like to shift into neutral and release the clutch pedal and remain at the stop using just the brakes if necessary to hold the car.
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.
35 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Outcome without a verified action link
And just in case you're still not tracking, let me repost this CUE by
Hi Guys.
You may have noticed I was silent for a week... was out at sea on a cruise. I actually really missed my 911!
I noted a bit of a rattling sound coming from the engine, which is intermittent. I'll try to post a video on here if some of you can listen to the sound. The "rattling" starts around the 13 second mark. The other sound is my dog barking.
Is it a heat shield? Bad cat? IMSB? Lifters?
Loose exhaust bolt maybe...? I have a stethoscope I can try using tomorrow night. Not sure I have a jack I can use though (all my jacks are large bottle jacks for trucks...).
Could it perhaps be a belt tensioner bearing going bad maybe? The sound does sound more like it's coming from the front edge of the driver's side rear wheel well.
Ok, it doesn't look like you have a safe setup to get to the bottom rear of the car. In that case, you will be limited to just checking the cats an mufflers with the mechanical stethoscope or a long screwdriver then. If you can get the rear up, you can check the IMS area and the cam cover.
I do plan to either get ramps or a low profile jack (Harbor Freight maybe) to get the car up in the air. I could swing by mechanic and ask him to put the car on the lift while I poke around underneath. He's pretty accommodating...
I had rattle at idle with ac on - mechanic told me it could be cat - I was checking it out the next week - held exhaust tip with oven glove and rattle went away - tightened up exhaust tip bolt - good to go - those things do get rusty so a soak in pb blaster maybe needed - anyway hope yours is as simple as that ...
When was the last time the serpentine belt was changed?
Do not jack it up, if you don't have the experience you may create more damage.
If this is your weekend driver, I won't use it until I know for sure the sound is not internal, coming from the engine, the last seconds of the video sounds more like a rattle but I'm not sure because the dog just take over.
I just had a clunk noise on my daily driver a Toyota, I placed the video on the forum and I got the answer from one of the members, right on the money, I don't know if you can attach the cell phone like I did, take a look
clunky noise - YouTube
The clip has too much movement to get a good fix on the noise.
My advice is to err on the side of caution and get the car flat bedded to a place where the car can be put on the lift with the engine idling.
I would think the location of the noise could be pinpointed in short order.
On the lift before you start the engine you can pull the oil filter housing and dump the contents out into a clean pan. What you see or do not see determines what you do next.
But as I stated above, err on the side of caution. Any running of the engine should be done in the presence of a tech you trust to make the diagnosis and effect any repairs.
I found the sound while the car was at the mechanic's lift, with the engine running. It's actually coming from the transmission (at least while engine is running with car in neutral).
I'll have the mechanic replace the transmission gear oil next week.
Is it possible it's coming from the clutch/flywheel assembly or you're sure it's from the internals of the transmission? If it's truly from the transmission, not sure a transmission oil change is gonna fix it
+1.
Your car is stationary and idling when the noise is happening, transmission parts are not moving. Fluid lubricates the internal gears, gears aren't moving when car is standing still.
I agree that this sounds like clutch/flywheel problem if indeed the noise is coming from the transmission area.
Might be from clutch / flywheel... but not sure how to trace it...
I don't feel any symptoms besides occasional rattling noise, so I'm not terribly worried. But might want to change the transmission gear oil anyway, since I just bought the car.
Hmm... that could be it, since the engine seems to rev fast and also drop RPM very fast as soon as I go to shift from one gear to another (I've been driving manual cars for over 20 years... RX-7s, older 911's, BMW M3, Z3, jeeps, etc - and I've never stalled cars as much as I am stalling this 996 at low speed).
Any way to know for sure if I have a light weight fly wheel?
I suspect you are in hypervigilant mode now.....listening and watching for anything and everything. A PPI = POSTPurchase Inspection may be in order for your car
Better yet, drop the engine: new clutch, RMS, AOS, IMSB, water pump/reservoir/t-stat/lines/hoses. Get these common ailments fixed, you should conceivably have a long, good stretch of worry-free driving (assuming brakes and rotors are still in great shape).
P.S. Watch out for the ignition switch and window regulators.....they're usually waiting in line given the age of our cars.
LOL, I love reading this forum with my morning coffee. As this is the only forum where almost any "noise or leak" prompts a fully serious advice of "dropping the engine and replacing everything".
Sailor did all of the PPI he could do, asked ton of questions about everything, covered every base he could. Now, he owns the car for two weeks...and next step is to drop the engine and replace everything that could potentially fail.
Edit, I also succumbed to the Rennlist paranoia. Now that I don't own the car, I can admit to it. I had a spare tiptronic that I would tow around with my Acura behind the Porsche...just in case. Spare engine was reserved on call in the Porsche salvage yard too. Tiptronic is 356lb, good thing that I lift.
Manual transmission equipped cars can under some circumstances produce a clutch or transmission rattle.
While my Boxster doesn't manifest this my Turbo does.
The circumstances are the car/engine/drivetrain be fully up to temperature.
Coming up to a stop concurrent with bringing the car to a standstill I like to shift into neutral and release the clutch pedal and remain at the stop using just the brakes if necessary to hold the car.
What I can hear often is a rattle that is not really in sync with the engine. That is it is not a steady regular periodic noise like a valve tick. Just about the time I think it is in sync with the engine its characteristic changes and it clearly is not in sync with the engine.
What I can do is fully depress then release the clutch pedal. This makes the noise go away and even after I release the clutch pedal the noise remains absent.
However, if I rev the engine a bit when it settles back to idle speed the rattle sometimes (most of the time) is back again.
Even though the transmission is in neutral the gears in the transmission are spinning. The input shaft is being turned and all the gears on this shaft are spinning their mating gears on the other shaft. (The transmission is after all a constant mech transmission.)
Any variability of the engine's idle speed -- and the Turbo is not the smoothest idling engine (courtesy of its pedigree/heritage the engine is a bit more raw) -- can bring about this rattle. (This is why my Boxster doesn't manifest this rattle, as its idle is super smooth.)
Another source is the clutch disc. It is driven by splines on the input shaft and there can be some play. How much depends upon normal manufacturing tolerances of the spline fit and the balance of the clutch disc. With a rougher idling engine this disc can rattle a bit on the input shaft.
A transmission fluid change may or may not affect the tendency of the transmission to rattle. I would change the fluid if it is due, or the fluid's change by date is in question, or the fluid may not be the right fluid and one wants to get back on track in this regard, and if the rattle is diminished afterwards that's just a bonus.
dude, really? you've been around here long enough to know what SARCASM is, right? if not, how about a
double entendre
?? but judging from your reply above
P.S. And just in case you're still not tracking, let me repost this CUE by
Barn996
and by another "in the know":
and FWIW, I am a fan of ACURAs, particularly the Integra and Legend
No need to. All of the answers to any 996-related question can be found in one comprehensive thread:
https://rennlist.com/forums/996-foru...996-forum.html
