1994 850 Grinding noise with accelerating from stop

[abscate]

Find a safe isolated place, like the drive up window for Britany Spears concert.


Get the noise going at low speed, then cut the key and shut the engine off to see if the noise ends.

This eliminates resonances in the exhaust and/or loose catalyst in the catalytic converter.

Let the car coast to stop, then restart.

[jblackburn]

I heard that and though that is the kinda grinding that sounds to me like the ABS system freaking the heck out.

Does your car have TRACS? If so, clean ALL of the ABS wheels sensors and reluctance rings on the axles - it thinks a wheel is spinning.

[jblackburn]

^ But then again, that wouldn't happen in park/neutral.

Normally a collapsed lower engine mount just vibrates the whole car badly below 2000 RPM or at idle.

Hmm.

[daversm]

Unsure about the car having TRACS, how would I check this? No ABS warning light on the dash.
Also something I noticed, the noise happens if I keep the rpm a little above idle, but it also happens very briefly if I take the rpm higher then let go of the gas. In other words I can hear the noise briefly when the rpms are coming down and cross the 1100-1300 range.. So definitely something just vibrating around that rpm range.

Im going to take a better audio recording, maybe put the mic under the car with some tape to get better sound recording.

Im also going to try turning of the engine when I hear the noise, and see if I can still hear it.

[abscate]

I'm still thinking loose stuff in the cat or exhaust

[timmybdaddyof3]

+1 on motor/trans mounts....if you have ever seen a motor with all of them failing you will notice the motor can flop around about 6" in all directions....sitting in neutral or park it will just be resting on its own weight against what is left of the rubber mounts...shift into drive and you now have the torque of the motor pushing against the motor and into whatever is left of the metal "safteys" on the mounts....give it gas and the torque is amplified, shift to reverse and the same process will occur in the other direction. An easy check is to watch the motor as someone slowly shifts between reverse, neutral and drive...the motor should not move as the trans engages.

Only reason I am saying to start there is I have has many customers come in with the complaint of a weird vibration/rattle/growl, etc only to discover that the mounts are shot, the motor is no longer sitting proper and is causing something else to make a noise....align the motor and all everything else literally falls into place
Just a thought

[daversm]

I think its either the motor mount or what abscate said. I'll take off the wheel and look at the lower engine mount. Im in the process of changing the rear struts so once I get that done, ill go back to trying to locate the noise.