I got this weird noise coming from the rear of my car. 92RS V6/700R4. When driving and the engine around 2000rpm, gear or speed doesn't seem to matter, I hear a rumbling in the rear. I hought it was the fuel pump, but sitting still out of gear and holding engine speed around 2000 or anywhere else it won't make the noise, only while driving. Can my pump only be making the noise under load? Wouldn't a problem with the rear end cause noise at all speeds? Doesn't seem logical that the rear would make noise at just 2000rpm in every gear. Is it possible the sound could be coming from my muffler, but again it should make the noise sitting still. Anyone have any ideas before I just start replacing things?

 

Moose,

Don't just replace things, but continue to analyze the problem. Try changing gears at the speed that makes the most noise, and see if the noise changes. Rear axle noise is generally relative to load and road speed, so if the noise frequency doesn't change with road speed, it may not be the axle.

Your ideas about the exhaust / muffler may be worth looking into, as well as tires, brakes, and the driveshaft.

 

To add onto Vader's post.... it could also be a semi loose mount somewhere, that with road vibration + motor shakin the car = your mount bouncing around enough to make the noise?

And do you have your spare tire, and scissor jack in the car still? If so, you should try taking them out and seeing if the problem persists, they could be bouncing around too. If those are the problem, then put them back and tighten them back down real good.

 

Those are good ideas, and I've got some time now to take some closer looks. I have done some more testing and I could only get it make the noise at the end of first gear right before it shifts.
It's turned to winter hear in colorado now and I hope I can avoid serious work for a while.

 

Get to a coasting speed and turn off the ignition (NOT IN THE LOCK POSITION). This will turn the elec. pump off and if the noise continues, it is not the pump.

 

I'll try that later this week. I took the differential cover off and the gears all look good, pulled the pass. axle too and checked the bearing, and everything looks normal. Road test again after I get more gear oil.

 

ive noticed this same noise in both my camaro and my girlfreinds firebird it seems to me its as soon as the tranny kicks into OD "4th" it has sorta a "hummmmmm" around 35- 40 mph with a light right foot lol
only time i notice it

the mechanics at my work said they didnt notice anything wrong with it when i had them take a drive in it
both cars are V6 as well

 

That sounds like your torque converter lockup switch...

 

thats what i figured anyway
but for some reason i wasnt sure
its what i told my girlfreind
just wasnt positive