I drive a 1997 4x4 blazer, 190k, recently has a rattle that I just cannot find. Audible at startup, gets louder when I put it in gear and don't give it gas, goes away after it has been driven awhile and warmed up. Sounds like its coming from the passenger side somewhere, any ideas or suggestions? Thanks!

 

Catalytic converter and or the heat shield for it?

 

imne has been doing this since last winter, actually started at start up on a real cold morning. been slowly going away. In fact its almost gone now

 

Could even be piston slap, very common in colder climates on this engine, and the 5.3L. Using a full synthetic oil and a good quality filter, (Wix premium, NAPA Gold, Purolator PureOne, Mobil1) will keep it in check. In some cases it will eliminate the noise completely after a few oil changes.

 

And here I was thinking the volume on your radio was the solution...lol

 

I had a rattle that would come and go. I got under the truck
at the right time to follow the noise. Found out one of
my exhaust hangars was barely touching the frame giving
me the rattle. I guess from heat and expansion it was there
sometimes and gone at others. Drove me crazy but really
did not hurt anything. Just annoying. A piece of electrical tape solved it.
The volume on the radio solution works too.