996 C4S Engine noise

Hi, I'm a recent purchaser of a 996 Manual C4S coupe... 2002, 78k miles. I've driven around 500 miles in the last 6 weeks, the bulk of it on a road trip. Having had the car parked up in the garage for the past 3 weeks, I took it out in the fine Easter sunshine for a drive around the Surrey countryside. A couple of things happened that may or may not be alarming. On startup -- a blast of smoke from the left exhaust After driving for 20 miles, the left exhaust sooted up compared to the right which remained clean On the return journey (20 miles), I noticed a tapping sound from the engine bay. I parked the car up when I got home, gave it a wash today, started it up again and shot a video of the sound coming from the engine bay, link to it below. Let me know what you folks think the sound could be... The car is due its minor service in May. https://youtu.be/E1XGmRndqoA

Really sorry but that's not good. Don't run the engine any more it's borked.

Based only on what I've read (I'm not a mechanic), query piston slap / tilt due to bore score (noting the LHS tail blackening)? Hopefully someone else will be along shortly to add first hand experience.

asterix_the_gaul - do you think thats really the case, the car drives and pulls great. When I went for a test drive it is was fine, and the subsequent road trip (400 miles no issue). Could something like this just occur overnight after being parked up for 2-3 weeks.? Only thing I have done is replaced the battery in that time. I've only had the car 6 weeks, the previous owner had some work done on it at a specialist just the month just before I bought it, replacing the oil separator. I enquired about whether they had uncovered any issues during that work and he said it was all clear, huge book of documented work shows its been well maintained. If it turns out to be a major issue do you think I have some reproach with the seller?

Doesn`t sound good I`m afraid, is the noise on the passenger side, bank 1, or the drivers side, bank 2 ? ( sounds like bank 1 to me ) Oil pressure good and level OK ? The car is on tickover in the video, does it go quieter if you up the revs to say 1500 rpm ? Flat 6 engines can occasionally smoke on first start after standing due to a little oil gathering in a cylinder, so that in itself is not always an indication of a serious issue.

Did you buy via private sale or dealer? The only way to be sure is to get the engine bores scoped by a reputable mechanic. Being optimistic there is a chance if the AOS failed recently that there is some oil making its way out of the exhaust etc and a puff of smoke on start up is not a concern in itself with the flat six.

It was a private sale. I'm not going to jump straight to the worst conclusion without getting it checked out. The seller seemed a decent sort, home counties, well to do middlie classes type. I'd be very very very surprised if he had knowingly stitched me up with a dodgy engine. I did a lot of research and asked a lot of questions on this subject and he was very reassuring, especially when he said it had been to a reputable mechanic the month before. I haven't checked the oil since I bought the car. I'll take a look at the oil level this week when I get a chance. Any advice on best oil for these cars if its running low?

Oh dear. I think you must have suspected the worst when you asked the question OP. I've heard lots of piston slap before and I'd be surprised if this was anything but. Check the video's out in this thread, particularly video 4. The whole series is worth watching as its incredibly informative, but 4 is on the diagnosis of bore scoring and what it sounds like. http://911uk.com/viewtopic.php?t=133303&highlight= Please keep us updated! :thumb:

Oil-wise Id be using Millers CFS nanodrive 10w 50. It's always worth letting the oil level check run before you start the car. Possibly it's lifter noise after the few weeks layup, fingers crossed... Get it booked in for a minor service inc oil change ASAP and get your specialist's opinion before proceeding.

...sounds like bore score rather than tappets to these ears; however I do hope the news is less painful to hear...

Please do let us know what happens.

Bore score doesn't happen overnight . Top up the oil if needed with 5/40 mobil 1 for now . Take the car to your local garage .. explain this to them and get them to listen to the noise .. Then if needed get a bore scope check done .. depending on what they say basically . I'm not going to comment either way as i think its best if a garage has a look and diagnoses what the actual fault is . if your location .. South London is correct then the garage i work at is not a hell of a long way from there , info if required .

Sorry to hear you're having such troubles, fingers crossed it's something that can be rectified without too much trauma.... ...but as an also relatively new member of the 996 C4S club and a similar mileage and vintage, please give us an update when you have one!

That is, as others have said, a worrying noise! Fingers crossed massively for you!

Sounds very similar to mine couple of years ago - also on C4S with 148K Noise appeared over night - also stopped after a few days - original post with video http://911uk.com/viewtopic.php?t=118575 Hope it's nothing serious!!