I think all the Gods are encouraging me towards build-up.. LOL!

Car now has developed this sound heard only after about 2k rpms (in motion/under load), only was to elaborate would be to provide an example:

I accelerate to 4k in 2nd gear and push in the clutch. Valvetrain sounds similar to a playing card flipping in bicycle spokes and quickly dissipates after a 1 – 2k drop in rpms. If I place the car back into gear (let’s say 3rd), the sound starts up real quick then dissipates… almost as if there was oil starvation occurring? The sound appears more upper-motor related. If I quickly put the car into gear w/o allowing the revs to decrease then the sound does not occur.

• I cannot re-create the sound while parked, regardless of how high I rev.
• Acceleration sounds/feels normal
• Occurs under boost and non-boost
• No drivability symptoms; runs smooth
• AFR appears w/in normal limits
• Not smoking

I would rule-out clutch-related issues, as the sound is exactly in time with rpms/valvetrain.

I’m stumped. The only thing that immediately comes to mind is an oil issue if the sound is intermittent. Oil is a new change, 20w-50, and is level.

Anyone with any similar concerns that could help me differentiate the diagnosis?

 

20/50 is way to thick and will damage your motor unless you run a block and pan heater so it starts on warmer/thinner oil.
Get the right weight oil.

 

Could be an exhaust leak...

 

I live in Phoenix where the nighttime temps are hovering around 80ş, is the recommended oil weight suggested by APS (per their install instructions), and been running that for over 28,000 mi. I argue that I have the correct weight.


MIA - oddly, it DOES sound a little like an exhaust leak, but it seems odd that it would occur only on decelleration (sp?) and w/in a limited RPM range suddenly (w/o injury/damage to the car).

It's on the 'things to check list' though - thank you.

 

I had an exhaust leak recently on my car as the reult of a clamp that finally loosened after 25k miles and I would only hear it when I shifted under load in the higher RPM range. Could barely hear it at idle in my garrage. Its something to look for though. Especially since you dont hear it on a free standing rev (Not enough exhaust gas velocity to produce it)

 

Welp... after driving it around in the back lot of the hospital, and now noticing darker-than-usual exhaust residue on the rear bumper cover, I'm thinking the turbo itself is ****.

I stood outside the car while someone else piloted around the lot; the noise is much more remarkable on the driver's side, and you can hear it (a little) as boost builds. When the throttle is lifted, there's that card-in-the-spokes sound. I did a lookover of what I could see piping-wise, no overt damage or loosening.

*sigh*

Trying to search to see what others have reported with regards to blown snails, so I can compare symptoms. Just kindof spooky with sudden onset, and gradually worsening since last nite.

 

Spoke with DynoComp (local APS dealer) - over the phone they are 95%+ confident that it's the clutch. Some things I left out (didn't think about) in my prev. explanation:

• 54,000 mi on OEM clutch
• 28,000 mi on APS turbo with ~450rwhp
• I drive like my *** is on fire
• Had a MAJOR, isolated slipping episode coming back from Los Angeles last week
• Can only emulate when car is in motion

They feel is is NOT turbo related as the sound/spin dies down too quickly, and if it were valvetrain issue it would be consistent, or variable upon temp changes.


Ugh........................................ well. Hell. Guess I'll be doing a search on viable clutch options for the APS ST. If anyone happens to have any addt'l input on other probable causes or affirms the clutch issue, please chime in

 

If it turns out not to be the clutch, you should check the flex section over the tranny for an exhaust leak, someone else had to replace theirs.

 

One of the first things I looked for. Mine is completely intact; I think his issue was related to constant install/removal.

If it turns out NOT to be the clutch I'm gonna be butt-hurt. It's a coin-toss as to whether to install myself or pay 7hr./labor to have it done.

 

I've been going strong on the OEM flywheel and JWT clutch - including lots of track and drag racing. Feels just like OEM...

 

I guess that's why they say first instincts are usually correct... *sigh*

UST for giggles, I pulled the dipstick. No oil? Odd.. I just did an oil change 3000 mi./47 days ago... myself... 5˝ qts.

Added the remaining ˝ qt. I had, went to Panda Express, mystery sound gone. Could not repeat it regardless of how I drove. Pulled the stick, still showed no oil. Bought another quart, filled, pulled stick, now reads at the bottom of the hatched line.

So, of course, now the dark(er) residue on the rear bumper makes sense - just gotta figure out why after 55,083 mi. the car is taking in oil. No leaks, no smoke, no smell, no previous symptoms. It just.... happened.

So good news: no imminent clutch replacement in my future.
Bad news: new onset oil consumption, with the possibility that driving around on low oil for at least a week. Yum.