So we were finishing up a 500 mile ski trip in N/E PA (handled great in the snow) with our 08 350 with a 4,000 lb camper on board, climbing up the hill into the development, and when I accellerated up the hill, the engine sound changed from its normal deep growl to a higher pitched 'tinny' sound. It stopped when i let off the throttle a little, and came back when I accellerated more. Abrubt change in pitch. Like from a A below middle C up to a D sharp.

Anyone else experience this? Should I be worried (my first diesel, so the noises are a little strange to me)? No loss of power, wasn't in regen, wasn't shifting (rpms were constant). Temp gauges all OK right in the middle.

Was the EGR doing something funny?

Have about 2,000 miles on the truck, it was running about 30 psig boost going up the hill, the temperature had dropped to about 6 degrees F. Had just gone down a long steep hill in tow/haul about 5 miles back.

 

it was probably the turbo whistle you heard. it is normal.

 

Yea, probably just the turbos spooling up to carry the weight over the hill.

 

Thanks for your help, but it wasn't a gradual increase, it was more like a switch was turning something on or off, or a gate opening and changing the sound.

Out of town right now, so I will have to take it out this weekend and see whats up. Covered with mud now from the road treatment in PA - we were on the Rt 80 Sunday about 5 miles away and about 3 hours after the 62 car pile-up on Rt 81 near Hazleton due to a snow squall.

 

I think your electric fan kicked in. Mine has a similar sound on a steep grade. Are you running with a grille cover? Your engine compartment temps will rise faster with a grille cover, even in cold snowy weather. If you have an EXT temp gauge run with it on, and see if it increases when you hear the sound. Proof of the fan kicking in.

 

My Truck Makes A Higher Pitch Clicking Sound Right Before It Upshifts To A Higher Gear .and It Is Always Right Before It Goes Into A Regen Cycle . But After The Regen It Is Fine Again .

 

The larger turbo is a variable turbo. Which means the vanes in it can adjust to give the appropriate amount of boost w/o requiring higher RPMs. These trucks can produce a lot of boost very quickly. It can go from 10 psi to 30+ psi in about 2 seconds.