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993 cab - engine noise


Well-known member
13 Jan 2006
can anyone help?? .. i have owned my '97 993 cab for just under a year and have had a tapping noise coming from the engine under revs since day 1. I asked the head service tech at porsche about it and he said its nothing to worry about and that some cars jsut sound that way!... i also asked my father in-law who has owned over a dozen various 911's and he said that 911's are known to sound like a "marble in a tin can"!! (is this right)??... i was just coming to terms with the fact that this is how it should sound then last week for about 3 days the tapping sound disapearred and the engine sounded sweet!!! .. Anyone have any ideas as to where the sound is coming from?? or how i can get rid?? .. any help would be appreciated!!

Migration info. Legacy thread was 58861
Post the question on Rennlist.com forum 993 section (subscription) and you'll get a larger number of replies from owners who have lots of experience taking this engine apart.

A search of Rennlist has pointed to pre-ignition - pinking - low octane fuel can cause it or in addition the collapse of a rubber tube in the advance retard air line.

"Hi jason,
FWIW, pinging, to me, sounds like marbles being rattled around in a metal can that has been wrapped in a blanket. Is that similar to the sound you're hearing?

I had exactly the same problem, for me, what solved it was the adaption of a small y-cord splitter that lives on the left hand side of the varioram induction tucked back in there. This spiltter collapses with time and effects advance/retard, causing the pinging/knocking /rattling under load. You can effect a repair with a small piece of 8mm brass tubing, there is a thread on this very problem on the board somewhere, perhaps some clever johnny can direct you to it, it certainly solved this very annoying problem for me.



Migration info. Legacy thread was 58866
Thanks Stevo...

its been driving me crazy... Hopefully this might be the problem... but will have a look at the rennlist forum also!!



Migration info. Legacy thread was 58868
The reason it disappeared might have been better octane fuel - try topping up with Shell Optimax (98 octane) or similar - the highest rated you can get of any brand would do.

Migration info. Legacy thread was 58869
yeah Stevo ..I only use 98 octane..(shell preferably but sometimes caltex premium)have done since day 1... its just started to get a bit cooler here (aus) in the last couple of weeks and i thought it might be the temp...but alas the irritating sound is back (along with the cold weather)!!

Migration info. Legacy thread was 58873

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