My truck has been making a light rattle on the highway. It is definitly load dependant. Cruising it makes no noise, but under load, going up hill on the highway, trailering, it sounds like an idler pulley or dare say waterpump or altenator. Anyone have this happen? Anyway to pin point it? I can't reproduce the noise in the driveway, so its tough to narrow down!

 

sorry to say i had that same situation you described happen to my 97 and i took it to the dealership and test drove it for a mechanic there and he said you got problems starting inside.
so i immediately started getting parts prices lined up for a rebuild or something and didnt even get the chance.
had to drive to work and 2 days later it left me settin about half way home.
everything looked good with oil and anti freeze but i had it roll backed home and pulled the motor.
ended up building a crate motor because a rod bearing spun

 

Are you sure it isn't pinging from running lean?

 

Uggg, Brian, don't say such horrible things!!!!!
Bluejay, ya, I'm 99 percent sure its not ping. Also, she's bone stock. I gotta drive it to Northern Maine for some snow mobiling this weekend...hoping and praying its nothing serious! Just did the starter this morning (unrelated issue). Starting to get bummed out, its a MINT 2006 with 79k on the clock. I would really hate for this truck to turn into trouble.

 

Throw a tank of full premium gas in it along with a bottle of Techron to rule out spark knock. At 79k you may need new spark plugs and some carbon burnout.

 

mine makes a rattle when i gas on it its coming from the ash tray area idk maybe i got some loose change down in there

 

whip lets hope it is something simple but my luck is not that way and my tapping sound under load cost me a little over 2 big bills.
i put shorty headers and an underdrive pulley on a long block crate motor along with a CAI.
the worst part was i was down for almost a week till i got everything i needed to put humpty dumpty back together again.