flohmann

A mysterious noise cropped up, hoping someone has an idea. It's an intermittent whine, only appears when the car is under power in first gear, lasts a second or two then disappears.

I've heard it when going straight or turning, and both when the engine is warm and when cold. Never at idle, never when braking, never at any gear above second (might actually only be in first, not positive).

I managed to capture it on the GoPro...

911mhawk

Any chance you're also hearing a change in drivetrain/transmission noise when in 5th or 6th? How many miles, have you changed trans fluid?

fpb111

Leave her home when you want to push speed or handling.

Sorry I got nothing but I couldn't resist.

flohmann

Nope, no noise in 5th or 6th.

55k miles. Not sure when/if trans fluid has been changed, but Porsche recommended interval is 90k miles, and I haven't noticed any difficulty shifting -- the noise happens only after the gear is fully engaged.

I took it to The Stable (noted local Porsche experts), and they heard it on the road but weren't able to reproduce on the lift and were stumped.

911mhawk

+1 excellent advice

911mhawk

I'd change the fluid for sure if it has never been done. Change oil too if you're waiting 7,500 or 15,000 or whatever the oil change interval is. Is the shop that cant figure out the noise where you bought it?

Macster

Is the power steering pump fluid reservoir level ok?

The noise could be a number of things. I do not think it is from the drivetrain, the transmission/diff though.

When I listen to the noise I think I know what it is. Then I listen again and I think it is something else.

It almost sounds like some brake pad dragging noise. Trouble is you can't apply the brakes even lightly when taking off as the DME cuts the throttle. But it would be interesting to know if applying the brakes affects the noise. I note while the noise was present when you took off the first time I didn't hear it the second time.

When was the last time you had the brake fluid flushed/bled?

Kind of a goofy thought but if you want take the car to a DIY car wash and use the wand to rinse the dust off the brake hardware. No need to jam the wand nozzle right down at the caliper but you want to aim the water spray at the caliper to rinse away the brake dust that collects on the piston dust boots.

You can blast the water spray to be sure the holes in the rotors are clear of any build up.

If you do the above be aware the brakes will not work very well when you go to use them afterwards so do a test slow down or two then drive the car around and use the brakes hard enough to get the brake hardware plenty warm to dry the brakes completely. If you park the car with wet brakes the rotors wil rust up something fierce and this could lead to other problems.

Anyhow, during another listen and I thought the noise was shifter cable rattle.

The I listened yet again and I thought something loose in the cabin. BTW, what is causing the other noises I hear? The pops/crackling noise. Sounds like you are driving over something crunchy.

With the engine off and cold check the serpentine belt for sharp edges. A sharp edge is a sign the belt's not tracking true and if this is the case some accessory drive has excessive bearing/shaft play and often this is the water pump.

Be sure you have nothing loose in the cabin. I almost drove myself crazy with worry when on a real rough/washboard road I heard some horrible knocking and it sounded like the car was coming apart under me and it turned out to be my metal cane had fallen down between the passenger door and the passenger seat and was the source of the noise. I had tossed the cane in the car just in cases as I don't normally use a cane but I wanted it just in case.

flohmann

Yeah, the other noise is just my GoPro rattling as it bumps against the e-brake handle. :-)

Regular oil changes and brake flushes, both most recently 5k ago.

I don't think it's brakes related, since my foot is never on the brake when it happens. But since it is usually on initial takeoff, I suppose it could be a pad intermittently dragging. I'll see if I can test that hypothesis. But since it happens rarely, could be hard.

Both serpentine belt and water pump have been replaced in the last 18 months, so seems unlikely to be one of those. Will check the power steering fluid level (tho if it were the common power steering noise, my understanding is that it would constant, no?).

Oh, and no, the shop I took it to is not where I bought it. :-)

Macster

Well, a dragging pad was what came to mind the first time I listened to the clip.

I note the noise was present the 1st time you took off but I didn't hear it the 2nd time. This suggests the 1st take off had a pad dragging but as the car's speed increased the pad was pushed away from the rotor and the 2nd time then there was no pad against the rotor.

Just a theory. These noises can be very hard to correctly diagnose when one is at the car.

fpb111

Sure sounds like a small bearing crying, maybe idler pulley? Is it only under excelleration or is it when you start a shift? Thinking throw out bearing or pilot bearing??

flohmann

Only under acceleration, I believe. Idler pulley might be right, but since it's impossible to reproduce reliably (and entirely impossible on a lift), pretty hard to diagnose which one...

flohmann

After topping off the power steering fluid level, the noise is no longer happening. At least not in the couple of days since I did it. My best theory is that the notorious valve in the power steering reservoir was being intermittently and momentarily starved of fluid when I was under acceleration. Just a guess. Will update the thread if it returns. In the meantime, another reminder that it pays to check fluid levels regularly.

Macster

Just a head's up but low power steering fluid can be a sign of trouble. The clutch slave cylinder can fail and route fluid to the small reservoir located in the front trunk under the panel just ahead of the driver.

Fluid stain on top of this panel can be another sign this is happening. But if the top of the panel is free of any fluid stain/sign that does not eliminate the slave cylinder. Remove the panel and check for fluid sign around the reservoir and in its general vicinity.

Another possible problem can be a power steering high pressure relief valve has failed and is routing fluid under too high of pressure to the steering rack. The fluid is forced out of the rack seals but is caught by the dust boots.

There can also be leak sign on the bottom of the underbody plastic panels.

You need to get the car in the air and carefully inspect the power steering and clutch hydraulic circuits for any leak sign. The couplings are quick disconnect but they have to decoupled correctly or they can suffer damage and leak.

At the front you will probably need to remove some panels and give the rack dust boots a grope/squeeze. If they feel like cheap breast implants they are full of power steering fluid and there you go.

"02996ttx50

that noise didn't sound ps steering reservoir related at all. but if its completely gone now its topped off? then you got lucky as thats not at all what the ps re whine sounds like. i agree your vids sound much more like an internal bearing whine and imminent failure. good luck w it.

flohmann

Yeah, may well be unrelated coincidence, only more driving will tell. And thanks for the tips on the power steering reservoir, Macster. No signs of leakage around that, and level there is correct.