Piston slap?

[pessemist]

I recently took out my 99' Porsche Carrera from winter storage. It has 104,000 miles. It started right up. No weird noises.

When I got home after about a 5 mile drive that included expressway and city portions, I noticed a metal clicking noise that was very loud right next to the right rear wheel.

Listening to some UTube videos it kind sound like Piston slap. It increased slightly with RPM's or turning on the AC.

Now here is the thing, I turned off the engine and turned it back on and the sound was there. Then I stuck the car in the garage for a bit, went back out and started it and couldn't hear a thing wrong. Ran it for 15 minutes with AC blasting to stress everything and it is still quiet.

My question is, how can I tell if I had piston slap? It was a loud sound at that one time but it has not returned.? Is there anything I should do? Could the storage have impacted this?

I'm thinking of selling it and now this comes up.

Suggestions?

Edited to add Ytube link of sound https://www.youtube.com/watch?v=Qle3bhfNizA&feature=youtu.be

[tonythetarga]

Typically, piston slap is due to wear and doesn’t come and go.
If you’re concerned about your cylinders, get them borascoped.
When I take my Cayman out of storage it needs to run until operating temp first. I may get codes after disconnecting the battery for 6 months, but once it runs, warms up at idle and then starts again later, any connection/sensor etc issue is fine.
If your noise comes back, try and isolate it with the ac off and see if it’s engine, alternator, air pump, water pump etc. lots of things running at the same time.

[pessemist]

Originally Posted by tonythetarga

Typically, piston slap is due to wear and doesn’t come and go.
If you’re concerned about your cylinders, get them borascoped.
When I take my Cayman out of storage it needs to run until operating temp first. I may get codes after disconnecting the battery for 6 months, but once it runs, warms up at idle and then starts again later, any connection/sensor etc issue is fine.
If your mouse comes back, try and isolate it with the ac off and see if it’s engine, alternator, air pump, water pump etc. lots of things running at the same time.

Thanks for the reply. I am guessing at this point.

Took the car out to show to a potential buyer. It started right up with absolutely no issues.

We took it on a 5-7 mile circuit. Warmed up on city streets then hit around 75mph for 3 miles than back down towards home on city streets again.

We pulled in the driveway and sat at idle talking and he mentioned a noise. We got out and a fairly loud repetitive metal on metal sound was very prominent at the right rear side of the engine.

We turned it on and off a couple times and the sound was always right there.

After he left I parked it back in the garage. 30 minutes later I started it up and at idle the sound disappeared!

Next day, same thing. Runs and sounds normal.

I listened to UTube and the sound was almost identical to a recording of piston slap that's why I was worried.

I am also thinking it could be detonation? I know I put in correct octant when I filled it but this is first time I ran it this year and down to below 1/4 tank. Think that could be an issue? I am going to fill it with the highest octane I can find and go from there.

[85eurocarrera]

search: Bore scoring Jake Raby

Although 99's aren't as affected as later models.

[tonythetarga]

Could be a valve guide dropping or something else mechanical like that. Probably not octane detonation.

[pessemist]

Originally Posted by tonythetarga

Could be a valve guide dropping or something else mechanical like that. Probably not octane detonation.

Can that improve with any kind of engine additive or cleanse? I'm thinking something like SeaFoam or Rev X or something along those lines?

[harmonyjim]

Possibly a stuck lifter that failed to 'pump up'?

[pessemist]

I uploaded a recording video to UTube to help figure this out.

Note: On cold startup the sound is not present.

After idling till warmup, the sound is not present.

After driving 5-6 miles the sound starts and continues even at idle.

https://www.youtube.com/watch?v=Qle3bhfNizA&feature=youtu.be

[pessemist]

Turns out to be a pulley noise.

[einsteiger]

Whew! Glad it was a pulley noise, as I was going to guess bore scoring. There is a great series of vids on that subject from Flat 6 Innovations.