So my '02 S60 is making a really weird grumbling noise (but no weird vibrations). When the car is cold and I start the engine and have it in park, it grumbles (and you can feel it from under the car). After the engine warms up a bit, the grumble tends to subside. When I shift it into neutral, the grumbling stops altogether. The transmission shifts smoothly, never had any problems with it at this point. Car has 135,000 miles.

Could this be a transmission issue? Something else? I don't think it's related to bad fuel. This has been happening for several tanks of fuel now.

Any help would be appreciated. Thanks!

 

sounds like dirt in the fuel system, run some cleaner through the tank. I use the Amsoil fuel system cleaner you might have to do it several times. had the same problems on my 90 740 and the 79 vette.