2015 Chevy 2500hd gas, noise when going up moderate hills

[bluewoo]

I think most of use remember the 4 speed trans that had the OD lock out (tow mode) But I don't think its needed anymore since the majority of trans control is by an ecm.

Hope the OP can find an answer on the noise.

[swmelton]

I have the same truck and tow a 11000 5th wheel through t.hr mountains of West Virginia. My gas mileage averages 7 to 8 MPG. I quit looking at the instant mileage it hurts to much but, yes I have seen as low as 3 when pulling a long grade. I read the manual and learned that shifting to M on a 6 speed will only give you 4th gear and no higher. They recommend shifting to M if the tranny is shifting up and down a lot, I haven't had to yet it will down shift fine and yes the RPMs can reach over 3000. SO it seems as if mine is acting the same as yours. I will admit I went from a 1500 5.3 to the 2500 HD and the 2500 is a MUCH louder truck all around.

[aceinspp]

Can not really hear the noise you are referring too. As far as engine temp. Just remember they are higher in newer vehicles. I'd still say the noise you are referring to is when the engine goes into a shift mode due to slight incline and you hear the air breather drawing more air into the engine. I hear it all the time with mine. Gets really noisy at times. Later RJD

[VinceU]

Originally Posted by verretcat

I am no mechanic but it just seems the strain of going up a hill causes something noisy to kick in and send more gas to the engine to keep the vehicle going at 2250 rpms. I guess I was hoping to hear from someone with this engine say that his truck has been doing the same thing for several years without a problem. Maybe it's because I'm a newbe going on my first long trip and wanting everything to go smoothly.

If the cooling fan is activated at that load due higher temp (fans viscous clutch engages), that will increase noise and fuel consumption. The Ford big blocks I've owned had this cooling system.


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[Dabmeb]

Have you ever tried running higher grade fuel on this type trip. Our 7.4 would haul fine on regular until it hit the mountain and then the difference was noticeable as GM retards time a lot on the first hint of knock. Running premium we never had an issue in the hills.


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