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YOUR RESEARCH996 engine noise recording-what's this then???
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Test get this noise
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Many of the 996's I have tested get this noise when parked with the backend higher than the front.
Leading evidence: 'Test get this noise' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Run mobil water (0w40)' (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 are running mobil water (0W40), change it to a better oil like a 5W50 or 15W50.
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Hi all,
I have a
996
with 36k miles on it. I've had it since 25k but for the last 5k I've had a slight knocking noise that I've noticed when starting up the engine (don't think it was there before.) This usually lasts for only a few seconds and then goes away. It only happens on cold starts
Yesterday after an unusually long (250 miles) drive the prior day the engine knocking continued for ~30 seconds before stopping. The other difference compared to "normal" was that I started with the car parked on a slight incline with the nose lower that the rear.
Now I know that it's normal for some noise on the 996 engine until the oils works it way to the top of the engine, but this is normally described as a rattling / slightly rough noise, rather than the lower base tone of a knocking. Today I've recorded the start-up noise and would like opionions on this . It appears between ~7-11 seconds in the recording and then goes away. The crunchy noise before I startup is me walking on the gravel of the driveway :-)
The recording is
here
.
Does this sound normal to you guys, do you get this noise, or should I be worried...?
Many thanks in advance
Jon
First guess.. A leaky hydraulic tappet that's being slowly compressed by an open valve while the engine is shut. It adds lash to a hydraulic valve train causing the tapping sound. After a few seconds, it pumps up from oil pressure.
Many of the 996's I have tested get this noise when parked with the backend higher than the front. I have not torn down the engine to find the cause, but it appears that this position causes mobil water to more easily drain away from componants in the bottom of the engine....crank or Intermediate shafts. Using a better oil most often eliminates this problem as well as parking level or with backend lower than front.
Could not get to sound file.
wdonovan - so if your guess is right, is this a problem that needs to be fixed, or lived with?
1999Porsch911 - The sound file is here:
http://home.btconnect.com/jon_ainswo...ne_startup.wav
Thanks
OK, I heard the sound...not what I thought you were explaining. It does sound like lifters. If you are running mobil water (0W40), change it to a better oil like a 5W50 or 15W50.
"wdonovan - so if your guess is right, is this a problem that needs to be fixed, or lived with?"
It's usually pretty inocuous but it could possibly be simply cured by thicker oil. Certainly worth a try. Not sure how it's viewed here, but I'd be tempted to put some "cleaner" in the oil for an oil change. Sometimes a slight sticking in the lifter makes it sluggish to react to engine oil pressure and pump up quickly.
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