38 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHstrange tinny slap type noise.
Leading reported evidence
Replace fluid
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
Unsuccessful attempts
1
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Read evidence and context
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Leading evidence: 'Replace fluid' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check loose spark plug' (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 not the water pump/alternator/power steering pump/pulleys, you may want to check for a loose spark plug.
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Suggestion
I recently learned that Porsche published a bulletin indicating that it doesn't recommend using anti-seize compound on spark plugs for any of their engines, this might have been the
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What do you think or suggest this noise could be. With the belt off, no noise. Belt on, noise comes back as you will hear in the you tube video I posted.
https://www.youtube.com/watch?v=YQJFrrW2Pm8
I should have mentioned that the noise also goes away at 2000 revs and higher. Also not as distinct or as noticeable when the engine is cold. So more distinct between 800 and 2000 revs.
If the belt is in good shape my vote would be #1: Water pump #2: Tensioner pulley #3: Other rotating accessory/pulley #4: Aliens. Take belt back off and try to wiggle each rotating item for lateral and radial play. If no defects call Mulder and Scully!
My first hunch is that sounds like a water pump to me. I would spin it by hand and try to move the pulley up and down and side to side to see if there is any play. Do the same with the alternator. Check all of the pulleys and tensioners as well.
If it stops when belt is removed, it has to be related to the belt I would think. Cats, spark plugs, exhaust leak, general rubbing of components, pretty much come off the table if it stops with belt off. The belt isn't making contact with something? Does it do it with the airbag out, but belt on?
Put a new belt on and see if you still hear it.
My turbo makes that noise for a minute after I wash it. On mine it is the back of the belt driving the alternator.
I should have mentioned that the noise also goes away at 2000 revs and higher. Also not as distinct or as noticeable when the engine is cold. So more distinct between 800 and 2000 revs.
Did you check the power steering pump fluid level? As has been stated, belt off - no noise, belt on - noise. So it is clearly evident it is something driven by the belt. Check everything driven by the belt. How many miles on the belt? Good time to replace it as well. Good luck.
Subscribed as im curious to what this could be.
+996 on not being the cats. I vote new belt as the cheapest fix. Might be slipping on one of the pulleys. Above a certain rpm it may not slip.
I replaced the belt under 1000miles ago with new alligator belt. No change. Will check power steering level. Fluid was changed by me about 10 000 miles back. Will try the hose in the ear method with back end jacked up. Also for loose spark plug OR a cracked sleeve (which is on the 99 job). I will wait till I get a warmer day for DIY and let you all know the result.
I had taken notice of that fact but thought maybe be less load on the engine with the belt off. Just MAYBE and it's a big MAYBE, it maybe not such a distinctive tapping noise if it was a loose coil wire or cracked sleeve. Worth checking it out when I am down there. I havent looked into it as yet but will in the next week or so when the weather gets warmer. I will keep you all informed when I start my DIY work.
A mechanics stethoscope works best for internal noise, bearing noise/vibration noise ect. A 3ft piece of 3/8 tubing works best for external noise, air noise, vacuum noise, exhaust leaks ect. Both listening devices are invaluable for pinpointing unusual noise.
I got the car really warmed up this time and the noise was very noticeable. Then I removed the belt and the noise is still there but not quite as noticeable. On tick over the odd chirp but a stab type blip brings it loud but only very briefly. It was then that I decided to book an appointment with Porsche in Lancaster PA for 9th May. I will make my move on the results of their diagnosis and will let you all know the outcome.
OK guys I did say that I would keep you posted.
I dropped the exhaust and changed plugs. The old ones had about 50000 on them. They looked fine. I found one of them on the drivers side a bit loose ( or very easy to take out) but decided to put new ones in all round anyway. That solved the problem. The engine is back on top form again now. I could tell when I fist started it on a cold engine, the Porsche rumble was back in the engine, I raced the hell out of it red lining it several times over a 10 mile drive and the tapping has gone. I am pleased to say that I will have to cancel my appointment with Porsche for this Monday. You all drive safe.
Hurdi: Glad for you!
Ahsai: Great remote troubleshooting(I'm not surprised that you nailed it, btw)! My question is why would this sound go away when the belt was removed when it was a loose spark plug? Do the accessories put that much of a drag on the engine at idle to make a loose plug rattle???
I think so. I heard the exact noise from a similar video long time ago and was intrigued. If you listen to Hurdi's video again, you could hear the rhythm is exactly once per cylinder firin at idle That makes it unlikely from any pulleys/water pump and highly likely spark related.
[Image-only post; no author-written text. Original image references:]
https://cimg2.ibsrv.net/gimg/rennlist.com-vbulletin/244x150/tenor_11_0cecf01be2bffc36def77cb7bce83cdfc48825fd.gif
Did you ever figure out what the squealing noise was? I have a 1999 Porsche 996 with the exact same noise. But with mine if you take the belt off I still hear the noise. I'd be interested to know what the problems was.
Thanks,
Steve
Thank you DBJoe996, I had done a coil and spark plug replacement about 3 months ago. Up to about a month ago I had not experienced the screeching sound after my 996 warmed up. I was amazed
to find that the number 3 plug was the loose one. That's the easy plug and coil to replace.
Torque spec on the spark plugs is 30 Nm (22 ft-lbs). I recently learned that Porsche published a bulletin indicating that it doesn't recommend using anti-seize compound on spark plugs for any of their engines, this might have been the
reason the plug loosened up. Thanks again
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