Jump to content

Server Lease Renewal/Software Licenses

Our yearly server lease, software licenses, as well as hardware operating costs, ARE due Dec 6th, 2021. Our current donations have fallen far short of the funds we need to renew. Please remember the RennTech.org community is Member supported so please consider a donation to help...  THANK YOU!

Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must log in to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings (limited)
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • View Reviews
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)

Recently purchased 996 very loud intermittent tapping


Recommended Posts

 I really need the help of somebody who is experienced with the 3.4 996 engine.  I purchased this car about a week ago, it has a very loud intermittent tap, unlikely it's the IMS as it's been upgraded to the LM bearing. one minute it'll start and purr like a kitten the next minute it'll sound like the engine is full of rocks. 

 

 No loss of power, drivability issues, smoke,  check engine light, oil consumption just the noise 

 

 These videos were taken five minutes apart?!?

 

 

Link to comment
Share on other sites

Sounds quite external to me. You may want to remove the aftermarket airbox and see if it's interfering with anything. Also check the entire belt and see if it's damaged anywhere. Then remove the belt and spin all the moving pulleys by hand (clockwise) and see if you can duplicate the tapping. 

Link to comment
Share on other sites

The rhythmn doesn't correspond to piston knock or valve train. Sounds too slow for those. The crank pulley spins about 12 revolutions per second at idle. Most of the pulleys are smaller so they spin even faster. Also there is some non uniform double tapping. Indeed a strange tapping.

Edited by Ahsai
Link to comment
Share on other sites

Oh man, that doesn't sound good at all. Have you checked if the clanking is comimg from one of the cats? You can place a screwdriver between the cat and your ear and try to hear the tapping. Another thing to check is if the spark plugs are all tight.

Link to comment
Share on other sites

1 minute ago, Twenty Clicks said:

 We have listened all over the engine, cannot isolate where the noise is coming from it appears to be coming from under the intake manifold 

It does sound like it's coming from there in the videos. However, there's really nothing rotational there other than the crankshaft after you removed the belt.

Link to comment
Share on other sites

One of the five timing chains may have extra slack due to the guide pads being worn out and coming into contact with something internal?  You don't have the noise at idle and it get louder at higher RPMs, making me think centrifugal forces are causing two components to come in contact.  Are there any aluminum particles in the oil filter?  How many miles on the engine?  It sounds louder than I would expect for a chain hitting the case or a cover and I would also expect the frequency to be higher (more taps per second).  Is the noise louder on the back of the engine?  Broken finger on the pressure plate possibly?  I would raise the car up and listen from underneath.  I would also remove the oil filter, cut it open and look for particles.  Worst case is that something inside the engine is making this noise and you will probably have particles in the oil filter and you are looking at a complete teardown to clean it out and rebuild.  By the way, the guide pads can be replaced with the engine in the car, but from what I have read, it is difficult.

Edited by Splitting Atoms
left out word. added sentence.
Link to comment
Share on other sites

Yup, that's the bank 2 scavenge pump. Can be removed (if enough space) without removing the cam cover. Hard to imagine it making such clanking noise though.

 

You can use a mechanic's stethoscope to pinpoint the source better.

Link to comment
Share on other sites

A couple of the posters thought the noise may be coming from the exhaust.  The catalytic converters are located behind the bumpers.  They do disintegrate internally when they get old, but the noise sounds too loud to be to be the exhaust.  But I would definitely take a closer listen to rule out the exhaust before I start opening up the engine.  Was the exhaust recently removed?  Could a bracket be lose hitting one of the pipes?

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.