eisenb11

Parked my car (2015 991) in my garage and was speaking with a neighbor. Heard a loud clank like something hitting sheet metal and saw this laying on the ground.


Looks like whatever it was attached to had a structural failure and sheered. Anyone know what this is? Am I safe to drive to the dealer in the morning?


I took a pic of the part (top and bottom) and where it was laying underneath the car.

JW1

Looks like one of many hex head bolts that Porsche uses. Could be from anything. Did try jacking up the car and looking under to see if you could locate where remainder of the bolt was on the car? Your car looks really clean under there. Lucky you don't get snow, salt, and sand during winter in Redondo Beach.

eisenb11

Ha ha, I'm from MI originally so I understand your pain! Don't miss the days of not being able to get into the car until I chipped the ice off of the door locks...


Yeah, I took a look and bolts like that are everywhere. No lift, but couldn't see anything obvious from the floor. Just had my intermediate service - maybe they overtightened something they took off. It probably isn't a huge deal.


Booked an apt first thing tomorrow morning @ 8:00 so we'll see where this leads.

STG

Could be exhaust tip bolt. Head looks snapped off.

Porsche_nuts

did they change spark plugs? maybe bolt from heat shield?

991carreradriver

Looks like a heat shield bolt.

ieatfishburritos

It takes quite a bit of energy to shear a bolt. From the provided evidence it seems it could possibly originate from something with mechanical energy.

We could form a tiger team and draw up a fishbone and disposition table, there are many possible origins I'd imagine.

GTOWN83

It connects the muffler bearings to the Johnson Rods. Text your pictures to the Service Manager at your local Porsche Dealer and ask him for his opinion.

Jabs1542

Haven't checked the muffler bearings in quite a while, but my wife regularly inspects my Johnson Rod

Code

Agreed. This also happened to my car. Apparently if you put a few drops of blinker fluid on the threads before tightening, it will prevent the bolt from snapping again, no matter how hard you torque it down.

Needsdecaf

Consider also that it could be from another car, got thrown up into your undercarriage and just fell out...

tstafford

Is there really something on the car called a "Johnson Rod" or is that a joke?

Pete

I think the RIBE refers to a "thread-forming" screw or what we Yanks call a self-tapping screw (http://www.ribe.de/sites/default/fil...2TkGySbxUz.pdf) If so, those are very easy to break while installing (ask me how I know) so it might have been starting to fail or partly fractured when it was installed and broke the rest of the way in your garage.

The self-threading type is often used for assembly reasons like it can be difficult if not impossible to get a nut and washer on the back side or because the screw goes into a blind hole and self-threading is easier than a bottom hole tap. I used to think of self-tapping as not being used in critical structural applications but my Cub Cadet lawn tractor uses self-tapping screws to secure the spindles to the deck and that's a pretty well-stressed application.

Bottom line is if it's for something like has been suggested like exhaust system, clamps, mounts, etc it may not be too critical to drive in for repairs. But if the number on the head is 129 or 12.9, that designation could be for a very high strength bolt.

HTH
Pete

Archimedes

Looks like a sheared Fetzer valve bolt. Ok to drive to the dealership.

KWP1911

Of course that's a real thing. Just like muffler bearings and blinker fluid.