This just started while my wife (eep) was driving last week. She came home and said it was making a "funny noise" when going up a hill (a very, very steep hill). I took it out and sure enough, in second gear at about 4500 RPM (when the engine starts really working) there is an additional rumble / rattle. The suspension is fine (no rattle in the steering) and I don't get a CEL so I assume the engine is ok. I reved the engine right to red line when I got home (in park) and nothing strange happened. I am at a loss. Anyone else had a similar experience?

 

tire(s) out of balance? or one has a belt seperation? that'll look like a lump or adip in th etire or sidewall

 

only in second? if not, mounts maybe?

 

does the rumble sound like a bunch of nuts in a can? if so it is definitiveley the motor, transmission mounts. they should be onwarrnty. if not, it might be rotary pre ignition (caused by cheap gas) I had both happen to me.

 

Thanks guys. I am taking it in next week for the 35k mile checkup. I am thinking mounts. When I sit idling, the car shakes harder than my 71 camero (350 straight pipes 10.7 in the 1/4, brag). I always put in 93 octane gas (live in higher elvevation and 91 was not giving me the "kick" to get up the mountains). A "new" sound has developed to accompany the rattle. It sounds like a vaccum tube sucking air. I can't find anything loose or broken, so I will mention that to the tech also.