996 M96 engine noise at idle.
06-05-2018, 07:53 PM
#1
996 M96 engine noise at idle.
Good afternoon,
I am currently trying to track down the source of a rattling noise in my 996. I recently removed the engine to replace the coolant tank, air oil separator, spark plugs, starter cable, IMS, etc. For the IMS I ended up just removing the outer bearing seal per LN Engineering's recommendation as I found out my engine was exchanged through Porsche somewhere around 6 years ago and has upgraded 997 parts on it including the larger bearing.
I have driven the car and it drives fine. I thought it was the mufflers or catalytic converters, but the noise is still present with the mufflers off and the cores appear to be in place in the converters which rules those out. The noise is only present when below 1k RPM. At or above 1k RPM and the noise completely goes away. Once I let off of the throttle and the RPMs rest back at idle the sound comes back. It also makes a noise when shutting the car off.
Here is the video where I start the car, increase RPM above 1k and then let it rest at idle again before shutting it off.
Here is the video where I increase the RPM to about 4k RPM then let it rest at idle again.
I am currently trying to track down the source of a rattling noise in my 996. I recently removed the engine to replace the coolant tank, air oil separator, spark plugs, starter cable, IMS, etc. For the IMS I ended up just removing the outer bearing seal per LN Engineering's recommendation as I found out my engine was exchanged through Porsche somewhere around 6 years ago and has upgraded 997 parts on it including the larger bearing.
I have driven the car and it drives fine. I thought it was the mufflers or catalytic converters, but the noise is still present with the mufflers off and the cores appear to be in place in the converters which rules those out. The noise is only present when below 1k RPM. At or above 1k RPM and the noise completely goes away. Once I let off of the throttle and the RPMs rest back at idle the sound comes back. It also makes a noise when shutting the car off.
Here is the video where I start the car, increase RPM above 1k and then let it rest at idle again before shutting it off.
Here is the video where I increase the RPM to about 4k RPM then let it rest at idle again.
06-05-2018, 08:39 PM
#2
Rennlist Member
Good afternoon,
I am currently trying to track down the source of a rattling noise in my 996. I recently removed the engine to replace the coolant tank, air oil separator, spark plugs, starter cable, IMS, etc. For the IMS I ended up just removing the outer bearing seal per LN Engineering's recommendation as I found out my engine was exchanged through Porsche somewhere around 6 years ago and has upgraded 997 parts on it including the larger bearing.
I have driven the car and it drives fine. I thought it was the mufflers or catalytic converters, but the noise is still present with the mufflers off and the cores appear to be in place in the converters which rules those out. The noise is only present when below 1k RPM. At or above 1k RPM and the noise completely goes away. Once I let off of the throttle and the RPMs rest back at idle the sound comes back. It also makes a noise when shutting the car off.
Here is the video where I start the car, increase RPM above 1k and then let it rest at idle again before shutting it off.
Here is the video where I increase the RPM to about 4k RPM then let it rest at idle again.
I am currently trying to track down the source of a rattling noise in my 996. I recently removed the engine to replace the coolant tank, air oil separator, spark plugs, starter cable, IMS, etc. For the IMS I ended up just removing the outer bearing seal per LN Engineering's recommendation as I found out my engine was exchanged through Porsche somewhere around 6 years ago and has upgraded 997 parts on it including the larger bearing.
I have driven the car and it drives fine. I thought it was the mufflers or catalytic converters, but the noise is still present with the mufflers off and the cores appear to be in place in the converters which rules those out. The noise is only present when below 1k RPM. At or above 1k RPM and the noise completely goes away. Once I let off of the throttle and the RPMs rest back at idle the sound comes back. It also makes a noise when shutting the car off.
Here is the video where I start the car, increase RPM above 1k and then let it rest at idle again before shutting it off.
Here is the video where I increase the RPM to about 4k RPM then let it rest at idle again.
06-05-2018, 08:56 PM
#3
Burning Brakes
Good afternoon,
I am currently trying to track down the source of a rattling noise in my 996. I recently removed the engine to replace the coolant tank, air oil separator, spark plugs, starter cable, IMS, etc. For the IMS I ended up just removing the outer bearing seal per LN Engineering's recommendation as I found out my engine was exchanged through Porsche somewhere around 6 years ago and has upgraded 997 parts on it including the larger bearing.
I have driven the car and it drives fine. I thought it was the mufflers or catalytic converters, but the noise is still present with the mufflers off and the cores appear to be in place in the converters which rules those out. The noise is only present when below 1k RPM. At or above 1k RPM and the noise completely goes away. Once I let off of the throttle and the RPMs rest back at idle the sound comes back. It also makes a noise when shutting the car off.
Here is the video where I start the car, increase RPM above 1k and then let it rest at idle again before shutting it off.
Here is the video where I increase the RPM to about 4k RPM then let it rest at idle again.
I am currently trying to track down the source of a rattling noise in my 996. I recently removed the engine to replace the coolant tank, air oil separator, spark plugs, starter cable, IMS, etc. For the IMS I ended up just removing the outer bearing seal per LN Engineering's recommendation as I found out my engine was exchanged through Porsche somewhere around 6 years ago and has upgraded 997 parts on it including the larger bearing.
I have driven the car and it drives fine. I thought it was the mufflers or catalytic converters, but the noise is still present with the mufflers off and the cores appear to be in place in the converters which rules those out. The noise is only present when below 1k RPM. At or above 1k RPM and the noise completely goes away. Once I let off of the throttle and the RPMs rest back at idle the sound comes back. It also makes a noise when shutting the car off.
Here is the video where I start the car, increase RPM above 1k and then let it rest at idle again before shutting it off.
Here is the video where I increase the RPM to about 4k RPM then let it rest at idle again.
06-05-2018, 08:59 PM
#4
Rennlist Member
Sounds like your DMF has failed, guess you didn't test it while it was out?
06-05-2018, 10:19 PM
#6
Rennlist Member
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I have a fuel vapor canister solenoid on my engine that makes a ticking/tapping noise. It only does it when the vehicle is fully warmed up and goes away above 1500 ish rpm. The solenoid can be found above bank one, behind where the air intake snorkel meets the rear wing.
I can feel the pulse of the tapping noise when the noise is present. This might not be the root of the noise you're hearing, but it's worth a look.
I can feel the pulse of the tapping noise when the noise is present. This might not be the root of the noise you're hearing, but it's worth a look.
06-05-2018, 10:32 PM
#7
Rennlist Member
Post a video of it and others can help identify said noise.
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06-05-2018, 10:54 PM
#9
I should have mentioned that this is a 2003 C4S Tiptronic. So no manual transmission. I started it without the serpentine belt and surprisingly the noise wasn't present from what I could hear, but there was still a rattle when shutting it off.
Here is the video running without the serpentine belt.
Here is the video running right after putting the serpentine belt back on.
Here is the video running without the serpentine belt.
Here is the video running right after putting the serpentine belt back on.
06-05-2018, 11:54 PM
#11
Rennlist Member
Still sound like something loose in the flywheel / torque convertor area( the rattle on shutdown).. Did you have any problems bolting the convertor back up?
06-07-2018, 05:44 PM
#12
I spun all of the pulleys by hand and they all spun smoothly. The water pump is brand new.
I removed the engine and transmission as a unit and them separated them. When I did the torque converter slid off the last set of splines and maybe half of a liter of transmission fluid leaked out, but I definitely installed the torque converter back correctly by having all sets of splines aligned because I was able to lock the converter through the hole in the top of the bell housing.
To answer your question, no, I did not have an issue at all bolting the torque converter back to the flywheel.
The only possible issue I see is that I reused the bolts for the flywheel and was not sure of the torque spec so I may have under torqued them. I reused the bolts for the torque converter, but the torque spec on those are so low I don't think it would make a difference.
Best regards.
I removed the engine and transmission as a unit and them separated them. When I did the torque converter slid off the last set of splines and maybe half of a liter of transmission fluid leaked out, but I definitely installed the torque converter back correctly by having all sets of splines aligned because I was able to lock the converter through the hole in the top of the bell housing.
To answer your question, no, I did not have an issue at all bolting the torque converter back to the flywheel.
The only possible issue I see is that I reused the bolts for the flywheel and was not sure of the torque spec so I may have under torqued them. I reused the bolts for the torque converter, but the torque spec on those are so low I don't think it would make a difference.
Best regards.
06-07-2018, 06:35 PM
#14
Race Car
Correct - flywheel bolts should only be used once.
Get yourself a copy of the workshop or Bentley manual or even the flat six innovations torque specs book
IMO a torque value is essential
Get yourself a copy of the workshop or Bentley manual or even the flat six innovations torque specs book
IMO a torque value is essential
06-07-2018, 06:38 PM
#15
They're grade 12.9 M10 bolts, at the torque spec prescribed by Porsche they are nowhere near yield strength (25NM initial + 90 degrees). Afaik that was the first revision from a straight 67 ft lb recommendation in the early manuals. Nowadays I hear 25NM + 120 degrees being thrown around as well.
Anyway, recommended normal torque (not torque-to-yield) for 12.9 M10 fasteners is 63 ft lb or 85 NM. 25NM + 90 degrees ended right around that mark (I did mine a few days ago).
tl;dr the flywheel bolts are not Torque-to-yield / stretch, thus can be reused.
Anyway, recommended normal torque (not torque-to-yield) for 12.9 M10 fasteners is 63 ft lb or 85 NM. 25NM + 90 degrees ended right around that mark (I did mine a few days ago).
tl;dr the flywheel bolts are not Torque-to-yield / stretch, thus can be reused.
Last edited by User 63031; 06-07-2018 at 07:03 PM. Reason: got some numbers wrong
