RADONCulous

We recently picked up a 2018 Cayman GTS (CPO). The car has ~2200 miles on it and seems to be in excellent condition. We purchased it from a Porsche dealer across the country. Today is the first day I have actually driven the car for a lengthy period of time / distance and I noticed a rattling noise that sound like its coming from the passenger side vent area above 70MPH--albeit this rattling noise could be anywhere in the passenger side rear quarter. It sounds like what I would imagine a bunch of rocks sound like if they were bouncing around / stuck in the vent. When I look in the vent I see that its mostly covered and I can't see anything in there and there is no evidence of any damage. I looked under the car and also in the rear wheel well and can't see any issues or any debris. The performance / temps don't seem to be affected but the faster it goes over 70 MPH the more the noise becomes obvious. Its an unnerving noise and never had this noise in our 981S / GT4. Any recommendations?

Todd B

Might not be the issues, but check the passenger side seat belt buckle. If the buckle sits in a certain spot it will rattle.

Mike Murphy

What speed does the spoiler raise on this car?

RADONCulous

Thanks Todd I always buckle the passenger side buckle, I also made sure that the seat is leaning forward and not rubbing, and thanks Mike I don't believe it to be related to the spoiler...

Dgkli

My question to myself would be, what would cause that type of sound strictly based on speed? I’m assuming you’re sure this is not related to some other factor such as vibration caused by road surface.

The main answer I come up with is wind speed. Which leads to maybe a flapping or vibration of a plastic part, e.g. fender liner or maybe underbody panel. I know,you said you checked, but are you certain there are no liners or panels that are loose/missing fasteners? How about the front fender liner? Other candidate (probably long shots): wiper, some piece of plastic in frunk?

Another long shot: 981s had an issue with gas tank rattles. I don’t know if that was solved in 982s?

RADONCulous

Dgkli thanks for your insightful post...the liner of the of the rear wheel was evaluated and is intact--I'll check the front one as well now that you mentioned it. The rattling literally sounds like what you would imagine a rock in a coke can would sound like if it was shaken and is more of a rattling or even flapping noise rather than any vibration. It does not appear to change performance in any sort of way. I spent some time trying to diagnose where the noise is and it sounds like the "area" where the vent is but its quite covered...its CPO so maybe a dealership is in order...

ElusiveDaveH

I would pull the intake air filter on the passenger side out and inspect housing for debris. At certain speed, you might be creating a pressure wave that might stir up pebbles.

PHB1969

I had a similar rattle at low speed - was diagnosed as a frunk gas strut being loose.

RADONCulous

@ElusiveDaveH any instructions on how to do this? Thanks for the rec!

@PHB1969 I'll also take a look, thanks!

Todd B

The 718 doesn’t have an air filter on the passenger side. Different setup then the 981.

But it brings up a good point to just check the vent on the passenger side and make sure everything is snug/clipped in.

ElusiveDaveH

Thanks for the correction Todd. I didn't realize Porsche changed the inlet air filters for the 718.

Todd B

It was a good thought, Actually made me go look at my car. I have a BMC air filter for my car I still haven't had time to put in. The engine cover has to come off, unlike the 981 where you accessed the filter in the rear trunk.

atwong1

I know we all love the roar of our engines, but those annoying rattles and noises? Not so much. I understand how even a small rattle can disturb the joy of the ride.

That's why I put my engineering background to use and created an easy-to-follow guide on how to find and fix those pesky car rattles. It includes a unique set of vibration simulation mp3 files - free to use for everyone. You can simulate the necessary vibrations without having to drive around, making it easier and safer to locate the source of the rattle.

Trust me; you'll love the peace and quiet on your next ride. Check it out! https://9xx.com/products/9xx-vehicle...tion-mp3-files

nitesho

(posted on the wrong thread - deleting)