While I want to hang onto my '96 626 for another year or two, my car has started making a rattling sound (coming from the engine or transmission?) when I am driving uphill. Any idea where the rattling noise is coming from and what a solution might be to fix it?

I have a rattling as well in a Nissan Altima I own and I had thought it was from a heat shield on my exhaust. They only use spot welds that do not hold up on these shields and when they become loose, they rattle. I also had the same problem on my Ford Explorer. I pulled off the rattling shield and now no more rattle. But the rattle in my Nissan is from the baffles in the resonater have collasped so check out your exhaust first. If it is a popping sound, try cleaning you fuel injectors or increasing octane in the gas.

Good luck!

You say it "rattles", do you know what detonation or "pinging" sounds like? Could it be that?

Thanks for the responses. I unfortunately know very little about cars. My car is a '96, and just within the past 4 months I've noticed a rattling noise when going uphill. I am not sure what pinging sounds like, but I would describe the sounds as a dull rattle (my interpretation of pinging is loud and higher pitched).

I recently bought some fuel injection cleaner but that didn't make a difference.