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rgracin
Newbie


Joined: 24 Jan 2014
Posts: 26



PostPosted: Sat Oct 07, 2017 12:20 pm    Post subject: 996 Turbo Engine Knock Comes and Goes Reply with quote

Hi

Our 2003 Turbo has developed a knocking noise at idle. It's ok when cold, but when up to temperature, there is a distinct knock knock knock sound which seems to cycle. It will knock say 10 times then go quiet for a few seconds then knock again. Doesn't matter if clutch is depressed or not, and disappears with revs.

Any thoughts on what it could be? Sounds to deep annoys to be a rapper I think.

Thanks

R
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2003 Manual 996 Turbo

Last edited by rgracin on Mon Dec 18, 2017 5:18 pm; edited 2 times in total
 
  
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Desert Dragon
Nürburgring


Joined: 03 May 2017
Posts: 424



PostPosted: Sat Oct 07, 2017 2:30 pm    Post subject: Reply with quote

Knock or rattle? Probably heat shields past their sell by date?
 
  
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NickHappy
Nürburgring


Joined: 27 Apr 2014
Posts: 395
Location: W.Sussex


PostPosted: Sat Oct 07, 2017 8:32 pm    Post subject: Re: 996 Turbo Engine Knock Comes and Goes Reply with quote

rgracin wrote:
Hi

Our 2003 Turbo has developed a knocking noise at idle. It's ok when cold, but when up to temperature, there is a distinct knock knock knock sound which seems to cycle. It will knock say 10 times then go quiet for a few seconds then knock again. Doesn't matter if clutch is depressed or not, and disappears with revs.

Any thoughts on what it could be? Sounds to deep annoys to be a rapper I think.

Thanks

R


Any chance of a sound clip or video? - would be useful.
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996UFO
Spa-Francorchamps


Joined: 28 Jul 2008
Posts: 295


2001 Porsche 996 Carrera 2

PostPosted: Sat Oct 07, 2017 10:08 pm    Post subject: Reply with quote

Oil scavange pump almost seems random. Same with any dry sump engine.

Disconcerting for someone who hasn't heard a dry sump engine before.
 
  
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rgracin
Newbie


Joined: 24 Jan 2014
Posts: 26



PostPosted: Sun Oct 08, 2017 6:58 am    Post subject: Reply with quote

Thanks for your responses.

It's definitely a knock. I replaced all the heat shields when I did the turbos a couple of years ago.

If it is the scavenge pump, then I fear it's on its way out as it's never sounded this loud before. I will try to get a sound clip.
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sim996
Trainee


Joined: 05 Aug 2017
Posts: 81



PostPosted: Sun Oct 08, 2017 10:18 am    Post subject: Reply with quote

Can you pinpoint with a mechanics stethoscope?

How many miles has it done, the timing chains can get quite rattly at idle.
 
  
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rgracin
Newbie


Joined: 24 Jan 2014
Posts: 26



PostPosted: Fri Oct 13, 2017 3:15 pm    Post subject: Reply with quote

So I checked the oil level which was in the middle of the read out. (Don't know why I didn't check that first!)I topped up to full and the knocking has disappeared!

So looks like it could be linked to the scavenge pump not liking the level st full.
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sim996
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PostPosted: Fri Oct 13, 2017 5:36 pm    Post subject: Reply with quote

Get your oil changed and analysed. It shouldn't knock at half full, it doesn't sound good to me. Get it checked out before you put miles on thinking it's ok.
 
  
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rgracin
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Joined: 24 Jan 2014
Posts: 26



PostPosted: Mon Dec 18, 2017 5:27 pm    Post subject: Reply with quote

996UFO wrote:
Oil scavange pump almost seems random. Same with any dry sump engine.

Disconcerting for someone who hasn't heard a dry sump engine before.


You may be on to something here. The noise returned, so have had a poke around with the mechanics stethoscope! The sound does seem to be coming from the scavenge pump on the drivers side. These seem to rarely go wrong, but the noise definitely wasn't there a while ago.

I've drained the oil and pulled the filter apart. A few very tiny metalic parts in the filter which are non magnetic and a couple of small flexible brown slithers of either tensioner guide or sealant nothing out of the ordinary according to the internet.

So, what's next. Are these pumps known to make this noise? Do i pull the pump and inspect for any damage? Do I refill with new oil and see how it sounds when warm? If still there then pull the pump and check filter again?

Could it be a problem further down the cam/sprocket from the pump with the sound eminating from here?

Loads of questions I know, but would. I'm erring on the side of pulling the pump, but I'd like to court opinions.
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ragpicker
Estoril


Joined: 14 Apr 2013
Posts: 3527
Location: North East England


PostPosted: Mon Dec 18, 2017 6:27 pm    Post subject: Reply with quote

You need to put pics of the filter on with the particles you describe if you want any proper help dude.

Equally I wouldn't take your interpretation of what the internet says as gospel - its a bit like trying to diagnose a medical condition through google...

Personally I've never had any brown slithers of anything in any of my oil filters on any cars, let alone my porsche's.

Edit: To spell it out: The chain guides fall apart when you dismantle the engine so they are well known to wear. The last thing you want is a disintegrating chain guide, reduced tension on the chains (which is why the noise could go under load), and then it slipping a tooth and ruining your engine.
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986 S - usually in pieces: http://911uk.com/viewtopic.php?t=112626
 
  
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rgracin
Newbie


Joined: 24 Jan 2014
Posts: 26



PostPosted: Fri Dec 22, 2017 8:15 am    Post subject: Reply with quote

Ok. Finally got time to take the pictures and post.






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coullstar
Suzuka


Joined: 15 Sep 2015
Posts: 1072
Location: Aberdeen/Torphins


PostPosted: Fri Dec 22, 2017 8:49 am    Post subject: Reply with quote

Get the oil analysed to see whats in it. Are those plastic bits hard? There quite big.
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ragpicker
Estoril


Joined: 14 Apr 2013
Posts: 3527
Location: North East England


PostPosted: Fri Dec 22, 2017 9:37 am    Post subject: Reply with quote

Yep they look like bits of guides to me. I wouldn't be driving that until a good indy has had a look at it fella.

Thumb
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Desert Dragon
Nürburgring


Joined: 03 May 2017
Posts: 424



PostPosted: Fri Dec 22, 2017 3:20 pm    Post subject: Reply with quote

I'd say you need to perhaps consider opening that engine up, stripping it and go through each component to check its still in spec and replace anything that isn't. Horrible but far cheaper than a rebuild if its goes pop. I'd certainly not start or drive the car again until this has been done. Whilst you're at it be rude not to rebuild it with stronger rods, GT3 oil pump, forged pistons, better headstuds and better turbos. Razz

One for 9e or ES? Sport and Classic or Porsche Torque are also worth a shout if you're not bothered about upgrading it.
 
  
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rgracin
Newbie


Joined: 24 Jan 2014
Posts: 26



PostPosted: Fri Dec 22, 2017 3:41 pm    Post subject: Reply with quote

Yep. I've decided to drop the engine for a proper look. Had a pm conversation with Ken at 9e. Very helpful chap.

Just need to break the news to the wife as it's (was) her daily!!
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Desert Dragon
Nürburgring


Joined: 03 May 2017
Posts: 424



PostPosted: Fri Dec 22, 2017 4:00 pm    Post subject: Reply with quote

rgracin wrote:
Yep. I've decided to drop the engine for a proper look. Had a pm conversation with Ken at 9e. Very helpful chap.

Just need to break the news to the wife as it's (was) her daily!!


I've met a few 9e customers and pm via this forum. You're in the best hands for a turbo according to them. They swear by Ken and 9e. Don't ask him about k16/39 hybrids. The bigger version - be an easier sell being the other halfs car Grin

Going down upgrade route only really worth it if the cars a keeper as its very expensive to do the work properly to Porsche standard.Alternative is to swap it for a newer 911. Nice low miles C4S cab PDK just come up for sale at 911V

Wink
 
  
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cheshire911
Estoril


Joined: 10 Jun 2012
Posts: 3731



PostPosted: Fri Dec 22, 2017 8:07 pm    Post subject: Reply with quote

The bill to strip and examine what's wrong and fix it and put it back together again is gonna be big enough without any mods. Doesn't sound good if you say you have knocking and those pieces of debris.
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rgracin
Newbie


Joined: 24 Jan 2014
Posts: 26



PostPosted: Sat Dec 23, 2017 8:19 am    Post subject: Reply with quote

We'll be keeping it standard. I'm hoping my saving grace is that the knock is not there permantly and it's at the top of the engine not the bottom.

I'll keep you posted on the progress, but it will be a slow burner as I think I'm going to take the engine out myself.
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MisterCorn
Long Beach


Joined: 08 Jan 2011
Posts: 6015
Location: Nottingham, England

2004 Porsche 996 Turbo

PostPosted: Sat Dec 23, 2017 8:42 am    Post subject: Reply with quote

rgracin wrote:
We'll be keeping it standard. I'm hoping my saving grace is that the knock is not there permantly and it's at the top of the engine not the bottom.

I'll keep you posted on the progress, but it will be a slow burner as I think I'm going to take the engine out myself.


Best of luck in getting it sorted. If you do the work yourself please post progress reports on here. I would be very interested to see the work involved.

MC
 
  
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wizard993
Donnington
Donnington


Joined: 23 Jan 2008
Posts: 11990


1966 Singer Gazelle

PostPosted: Sat Dec 23, 2017 2:08 pm    Post subject: Reply with quote

Often it’s one of the hydraulic valves. Bin 0w oil if that’s what’s in it and go to 10 or 15w as this can clear the problem(sometimes)

With 10 or 15w you just have to be more careful with the revs until it’s up to temp......so keep it under 3000 rpm.
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