991.2 Piston Slap
07-16-2018, 07:23 PM
#16
The slapping only happens once in a blue moon(only when I crank the motor), there would be no way easy way to get an audio of it. It has happened about 4 or 5 times in the year I have owned it. I have about 6,700 miles on it. If the PSM light comes on again I will take it in and talk to them about the noise. I have heard other people here mention the piston slap, but maybe it is something else.
The noise lasts for a couple of seconds after cranking the motor.
The noise lasts for a couple of seconds after cranking the motor.
07-16-2018, 07:42 PM
#20
Racer
Thread Starter
someone here referred to it as piston slap, maybe I heard it was a lifter as well. I don't really know but it sounds bad but goes away after a couple seconds and does not happen very often.
It is a rattle sound
It is a rattle sound
07-16-2018, 09:19 PM
#22
Just in regards to Costco gasoline, I have a good friend that does a ton of tuning in the NW and worldwide now for the N54 motors in the BMW Twin Turbo Platform. He has seen many cars on different fuels from E85, Meth, pump gas ect... He has told me before to never run Costco gas in my BMW, they do not have the best gas.. No longer do I have my BMW, but I have my Porsche. Still I won't put that gas in my car.. Not saying this is "the issue" and my 911 is N/A, so I am sure it may do fine on their premium. However, it is quite possible you could have got a bad batch of gas from the station, if it is pinging/detonating.
My 135i started going in limp mode once, stuttering, and coding, for about a day. Took it in, they couldn't find anything, burned through the fuel between test drives, diagnosing, put new gas in, ran fine. No other issues, this stuff does happen from time to time.
My 135i started going in limp mode once, stuttering, and coding, for about a day. Took it in, they couldn't find anything, burned through the fuel between test drives, diagnosing, put new gas in, ran fine. No other issues, this stuff does happen from time to time.
07-17-2018, 01:12 AM
#23
Rennlist Member
It's almost certainly not piston slap. Piston slap sounds like hitting a bell with your hand on it muting it - I've never heard it in a boxer engine. Piston slap also never goes away over time - it's a "feature" of a worn engine that is persistent.
It's most likely the hydraulic lifters - especially if its a high-pitched ticking. On cold start, one or more of them is not pressurized, and you hear the metal-on-metal contact until the film builds under pressure. This is common on all post-964 engines and is not a cause for concern unless it lasts for an extended period of time (say 15 minutes) after cold start.
My new Carrera T does this if I let it sit. I've found if I drive it hard (lots of 4K + revving, otherwise known as an Italian tuneup) that it reduces the tendency.
Hope that helps!
cheers!
It's most likely the hydraulic lifters - especially if its a high-pitched ticking. On cold start, one or more of them is not pressurized, and you hear the metal-on-metal contact until the film builds under pressure. This is common on all post-964 engines and is not a cause for concern unless it lasts for an extended period of time (say 15 minutes) after cold start.
My new Carrera T does this if I let it sit. I've found if I drive it hard (lots of 4K + revving, otherwise known as an Italian tuneup) that it reduces the tendency.
Hope that helps!
cheers!
07-17-2018, 09:18 AM
#24
Almost impossible that it's piston slap, which is caused by pistons that are too small for the cylinder bore, causing them to rock in the bore, causing the skirt to "slap" the cylinder wall. It happens on cold engines when the pistons haven't thermally expanded yet. Certainly has nothing to do with gasoline or octane. This is surely not your problem on a new, factory engine. I would take it to the dealer for diagnosis.
07-17-2018, 10:51 AM
#25
Racer
Thread Starter
I appreciate the responses. It alarmed me because of the intensity, at least it seemed more intense, this time. It more often happens after the engine has warmed all the way up and I stop for coffee for about 30 minutes. When I get back in the car and start it, the rattle will last for a couple of seconds and then things are normal. This time the PSM failure light came on in less than a minute, but maybe this was coincidental. Things seem normal so far today.
07-17-2018, 11:17 AM
#26
Three Wheelin'
07-18-2018, 11:04 PM
#27
Rennlist Member
What I thought was a noisy valve lifter turned out to be piston slap but this was in a 99 M96 motor with 98000 miles on it and was a known failure item with that series. I found that out the hard way when the rod in #6 went thru the case. One thing I noticed though was it got real noisy when the oil was hot. I agree with those above: to have true piston slap in a 9A1/A2 motor with no miles would be pretty rare if not impossible but I think the dealer would be able to determine that. I'd at least go in and have them note it on the car's service log. If for some reason you actually have slap I doubt the motor would make it to the end of your factory warranty anyway.
07-18-2018, 11:29 PM
#28
100% it’s your lifters filling with oil after you let the vehicle sit. Totally normal and you can google it to hear the noise. It doesn’t sound like you have the mechanical ability to be able to identify piston slap but it’s easy to make a thread that will last for years mentioning a concern you don’t have and worrying many owners!