MY00 996 c4 developed a tapping sound........ Some advice?
Discussion
Firstly, thanks in advance for any musings 
Secondly, the car's going in for it major service in a few weeks anyway, so I can get it looked at professionally.
Car: 996 c4 standard. Manual. 91k on the clock.
I noticed the sound after topping the oil level up - tapping at tick over that increased with revs. (Mobil 1 5w/40). Perhaps a different grade of oil should be used (uk user).
No smoke at all.
No drop in performance.
Went thru its mot and sailed the emissions.
My (VERY) limited understanding based on logic and rational thinking(!) is that the culprits of hydraulic lifters, for example would cause some seriously unpleasant and very noticeable side effects.
Therefore, I think I'm left with the extremities of fault, either borescore and/or D-chunking, (would this have affected the emissions?) or something much less sinister?
Thoughts would be most welcome.
Will be taking it to SVP in Bromsgrove (closest specialist)
Thanks again in advance,
Dan
Secondly, the car's going in for it major service in a few weeks anyway, so I can get it looked at professionally.
Car: 996 c4 standard. Manual. 91k on the clock.
I noticed the sound after topping the oil level up - tapping at tick over that increased with revs. (Mobil 1 5w/40). Perhaps a different grade of oil should be used (uk user).
No smoke at all.
No drop in performance.
Went thru its mot and sailed the emissions.
My (VERY) limited understanding based on logic and rational thinking(!) is that the culprits of hydraulic lifters, for example would cause some seriously unpleasant and very noticeable side effects.
Therefore, I think I'm left with the extremities of fault, either borescore and/or D-chunking, (would this have affected the emissions?) or something much less sinister?
Thoughts would be most welcome.
Will be taking it to SVP in Bromsgrove (closest specialist)
Thanks again in advance,
Dan
I'm not a big fan of using the wrong oil to possibly quiet (temporarily at best) a malfunctioning item like (possibly in this case) a zero lash adjuster and subjecting the rest of the engine parts to inadequate/subpar lubrication.
Unlikely the noise is a d-chunk failure.
My advice would be to get the car in for service earlier or at least have the noise listened to and diagnosed. I would be reluctant to continue to drive the car, run the engine any at all, until this was looked into by a professional/qualified technician.
I do not know the miles on the oil currently in the engine and how you drive the car but it could be the oil is past its change by date. That is given the miles and type of usage it is exceptionally contaminated with unburned fuel and water and has thinned out enough the tapping is the result of this.
Have the oil/filter changed. If the noise is still present afterwards the car is in the right place to have this noise source ID'd and you to get the best advice as to what to do next.
Unlikely the noise is a d-chunk failure.
My advice would be to get the car in for service earlier or at least have the noise listened to and diagnosed. I would be reluctant to continue to drive the car, run the engine any at all, until this was looked into by a professional/qualified technician.
I do not know the miles on the oil currently in the engine and how you drive the car but it could be the oil is past its change by date. That is given the miles and type of usage it is exceptionally contaminated with unburned fuel and water and has thinned out enough the tapping is the result of this.
Have the oil/filter changed. If the noise is still present afterwards the car is in the right place to have this noise source ID'd and you to get the best advice as to what to do next.
Thanks for the reply - I'm working on logical thoughts rather than Porsche paranoia!! 
So the D-chunking etc seems a worst-case.
The oil's pretty new too, and I'd be the first to say if I'm a lout, but it's always driven sympathetically if I'm being totally honest.
My nearest specialist is about 40 miles away, so will be booking it in at the earliest convenience. Got another car to drive in the meantime should I decide to go anywhere
Thanks,
Dan
So the D-chunking etc seems a worst-case.The oil's pretty new too, and I'd be the first to say if I'm a lout, but it's always driven sympathetically if I'm being totally honest.
My nearest specialist is about 40 miles away, so will be booking it in at the earliest convenience. Got another car to drive in the meantime should I decide to go anywhere
Thanks,
Dan
Mine acquired a tap / rattle after the last time it went in for some work. Garage it originally went to told me the engine was on it's way out and it needed a rebuild / replace.
Had a mechanic / garage I know well and trust check it over fully, they even ran it up on their rolling road for a number of runs and holding at different speeds with an ocillascope strapped on, not a dreaded Porsche noise, it was actually tappets. I've not had them done as yet as I'm doing the clutch and will get the whole lot done in one anyway. Not every noise spells doom and gloom in a 996 but do find a good garage that you trust. There are a number of specialists who will tell you EVERYTHING is terminal as they want/need the revenue but always get a second opinion if you have been given a death sentence.
Had a mechanic / garage I know well and trust check it over fully, they even ran it up on their rolling road for a number of runs and holding at different speeds with an ocillascope strapped on, not a dreaded Porsche noise, it was actually tappets. I've not had them done as yet as I'm doing the clutch and will get the whole lot done in one anyway. Not every noise spells doom and gloom in a 996 but do find a good garage that you trust. There are a number of specialists who will tell you EVERYTHING is terminal as they want/need the revenue but always get a second opinion if you have been given a death sentence.
Interesting
surely stuff like piston-slap etc (the unpleasantly wallet-emptying stuff) would have had an adverse effect on the emissions and car output (such as smoke etc)......
Could be tappets the. Will see what the garage says - haven't used them yet (only had the car 12 months) SVP in Droitwich: look a good firm.
Dan
surely stuff like piston-slap etc (the unpleasantly wallet-emptying stuff) would have had an adverse effect on the emissions and car output (such as smoke etc)......
Could be tappets the. Will see what the garage says - haven't used them yet (only had the car 12 months) SVP in Droitwich: look a good firm.
Dan
What grade oil did you use - sometimes older higher mileage cars are quieter if the oil grade used is one up from that originally recommended when they were new and tighter and sometimes this quietens the lifters when the car is hot (although it often takes a hot run to fill the lifters with the thicker oil).
If the noise goes away with revs when hot might well be the oil in the lifters.
If you can count it over say 10 seconds on tickover - if it is around 60 or so it may well only be that it is the oil or a tired lifter.
If it is there from cold possibly piston slap.
If a harder knock getting louder with revs - possibly a big end going.
However light ticks that no one has yet been able to identify (including us despite trying all sorts of things) may be due to unbalanced tickover ignition cycles between different cylinders causing primary chain snatch through the hydraulic tensioners - and if so not to worry about - a lot do it.
Baz
If the noise goes away with revs when hot might well be the oil in the lifters.
If you can count it over say 10 seconds on tickover - if it is around 60 or so it may well only be that it is the oil or a tired lifter.
If it is there from cold possibly piston slap.
If a harder knock getting louder with revs - possibly a big end going.
However light ticks that no one has yet been able to identify (including us despite trying all sorts of things) may be due to unbalanced tickover ignition cycles between different cylinders causing primary chain snatch through the hydraulic tensioners - and if so not to worry about - a lot do it.
Baz
Hi Baz,
Apologies about the late reply - had band practice tonight!
Many thanks for your detailed feedback.
The oil was Mobil 1 5w/40.
I will count the "ticks" in the morning and feedback accordingly.
With reference to the more unpleasant issues, would piston slap and big end going have any other symptoms?
I'm only asking as the performance is still fine, as was the MOT emissions.
No smoke is present either.
Thanks again,
Dan
Apologies about the late reply - had band practice tonight!
Many thanks for your detailed feedback.
The oil was Mobil 1 5w/40.
I will count the "ticks" in the morning and feedback accordingly.
With reference to the more unpleasant issues, would piston slap and big end going have any other symptoms?
I'm only asking as the performance is still fine, as was the MOT emissions.
No smoke is present either.
Thanks again,
Dan
DanoS4 said:
Hi Baz,
Apologies about the late reply - had band practice tonight!
Many thanks for your detailed feedback.
The oil was Mobil 1 5w/40.
I will count the "ticks" in the morning and feedback accordingly.
With reference to the more unpleasant issues, would piston slap and big end going have any other symptoms?
I'm only asking as the performance is still fine, as was the MOT emissions.
No smoke is present either.
Thanks again,
Dan
Relax. Piston slap and a failing big end don't tick. (There are exceptions, there always are, but the two problems are rare to begin with.)Apologies about the late reply - had band practice tonight!
Many thanks for your detailed feedback.
The oil was Mobil 1 5w/40.
I will count the "ticks" in the morning and feedback accordingly.
With reference to the more unpleasant issues, would piston slap and big end going have any other symptoms?
I'm only asking as the performance is still fine, as was the MOT emissions.
No smoke is present either.
Thanks again,
Dan
Reading your post further on down a tick that comes on after the engine has run a while suggests an exhaust leak.
DanoS4 said:
Interesting and "thanks"
My only other thought was lifters........
Let me add one more thought to your list of thoughts...My only other thought was lifters........
Get the car, the engine listened to by someone with experience dealing with these engines and someone who is at the car and can listen with if necessary to pinpoint the source of the noise with a stethoscope.
Knowing where the noise is coming from is very important to knowing what is causing the noise.
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