After poking around under the dash, I was able to ascertain that the
rattle was indeed coming from inside the airbox right where the two
water lines come through the firewall. Pulled the heater motor to see
if I could reach around to feel a screw and discovered that the core
or evap was right in the damn way of me getting my hand to the spot
making the noise.
I contacted a great mechanic here in Dallas that does work on my truck
outside of the normal maintenance items. While I sat in the truck, he
messed around under the hood until we found the source. It was the
actual metal (aluminum?) pipes that go through the firewall. There
was a lot of slop and they were apparently vibrating against each
other or something just inside the airbox.
Went to Lowes, bought some insulating tape and crammed as much
possible through the firewall around the pipes.
Rattle gone. In the process, many undone items from the dealer were
found (missing bolts, missing high-side cap, loose bolts, etc). No
more trips to that dealer ... (Grapevine Dodge in Grapevine Texas). I
expressed my disappointment with them ... a service manager was going
to call me "right back". 3 months later ... nothing.
S I G H ...
Got in my truck when it was cold a few weeks back and the ability to
change from floor vents to defroster was lost in a flash along with a
wonderful grinding sound. Took it to the dealer and they replaced the
mode door assembly.
Since that time, I have a vibrating sound coming from that area when
at idle in drive or reverse. I have crawled underneath and made sure
all screws and bolts are tight. All wire harnesses appear to be
secure. I removed the glove box, poked around and didn't detect
anything loose. So, I crammed my head underneath the dash again ...
and it sounds like the rattle is coming from *inside*
the airbox near
where the heater motor is attached.
2004 Ram 2500, 4x4, CRD, QC