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2000 GTP Grinding-ish Noise with Hard Acceleration

E

epon

New member
AT 120k, recently went through and replaced wheel bearings with Timkens all the way around, Monroe quick struts all the way around, power steering and ATF fluid swap, new serp belts, new tires, aligned etc.

All this work was done pretty close to each other so I'm not sure if its related to something that was done in the service.

I'm now getting a muffled low pitched grinding/rubbing noise under hard acceleration from a stop. Under normal driving, no noise and feels like it's shifting well. I can duplicate/ increase the noise a tiny bit by stepping on the brake and giving it a lot of gas at a stop (without moving) so I'm shying away from the CV joint with a torn boot as the culprit. (silent under low throttle and no clicking in turns). Noise is also apparent when hard accelerating at speed also. Torque converter slipping?

When I changed the ATF and filter, I left the old filter's oring in the housing and just pushed the new filter into it. It seemed like it was snug and fully seated. Old fluid was good and red and didn't stink. ATF levels are good.

When I changed the struts I didn't grease the top of the plates or strut bearings, wondering if maybe they're shifting around slightly under torque.

Took it to a shop and they can hear it but aren't sure, suggested maybe loose exhaust but that doesn't make sense given the symptoms.

Searched around and found a few instances of same symptoms but no resolutions.

Help?
 


and I guess it's the axles/CV joints ... but that doesn't explain the noise when stopped with both brake and throttle applied. Seems to be the same noise. bumped my own thread I guess :/
 
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I did notice the motor moving aprox 4" from idle to about half throttle and back. No noise from engine bay area with hood up and assistant at the controls. I did however hear it very well when I stuck my head inside the car near the steering wheel. Kinda sounds like the grunting of a brake but the car isn't moving and its consistent with the noise at speed from a stop.

With 120k on the clock, I suppose it's a prudent swap. Any recomended replacements?
 
Flipped the dogbone bushings and still there. I can reproduce the noise consistently in D with brake fully applied and at a bit more than half throttle the grumble starts and is a consistent tone. In R it doesn't make the noise so atleast I have another clue. Still thinking maybe transaxle and or bottom motor mount but will run it by a shop to see if a pro can put the clues together for a solution.
 


Had I not determined the noise exists while stopped I would think the same thing. Maybe its loading force againts the cv joint and causing the noise. Appointment with the shopfor this afternoon so we shall see what they say .....
 
Following up to say the shop was too loud and/or the guys hearing was not so good but he did say he heard something and to just drive it until it gets louder, and if I want to throw money at it change the motor mounts.
 
When sc belt is off the noice is still present, doesnt seem to do it in reverse which points to trans. itself or possibly something to do with last ATF swap (filter only reused o-ring, maybe filter to pan contact) Drivers CV boot is bad but joints dont click in turns or circles in parking lots. Guess the next logical place to throw money and time is the driver's side axle or another professional opinion. Maybe someone can benefit from this even if I wind up donating the damn thing to NPR.
 
Changed pass side control arm and half shaft, did another ATF fluid swap and added the red bottle trans gaurd. Found plenty of black stuff clinging to the pan magnet and still groans when accelerating from a stop. Guessing I need to find a good trans guy.
 


Also noticed tonight as I'm backing up a hill, where the car would normally hold itself stopped or crawl up an incline with an idle and foot off the brake, it began to roll forward. Another clue ... hoping someone knows what it is ... don't really want to get rid of the car.
 
Hail to the Chief !!! They figured out the Rock Auto stabilizer bar I ordered and installed was labelled wrong. The side that says drivers side is actually the passenger side. :mad: Downpipe hitting the stabilizer bar as the motor rocked back under torque. Hopefully this thread will save a Rock Auto shopper some of the headaches I had.
 
So that fixed it? Just a vibration? It was weird that you mentioned the car wouldn't hold itself on a hill with decent acceleration, and that the magnet had a lot of gunk on it for few miles. Makes it sound like it's slipping, but I'm glad you got it figured out.
 
Yep motor tilting back on acceleration, it may still be slipping but the grinding noise is gone.
 
Part# is DOR 927-100 and RA declined crediting me the part cost and offered me $12 in store credit for the shipping. :th_scratchhead:
 


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