Truck doesn't coast well (resistance)

[WorkDog]

97 F350 7.3 XLT 4dr 8' box stock truck 145k

Just bought the truck and I love it but trying to work out some minor kinks. Always owned full size trucks but first diesel. When I'm at cruising speed lets say 45 and I let off the gas it slows very rapidly as if I was in to low of a gear, but its not. For example going down a very steep hill it doesn't gain any speed at coast, slows if anything. Don't think it's brakes cause I'd smell something. Guy I bought it from said its got a rebuilt jasper trans 6000 mi ago, shifts nice. Wondering if this is what's causing my 10mpg. Sound familiar to anyone? Ideas?

[kramarj]

The torque converter is probably locked. Next time you drive it, tap the breaks at the top of the hill, that will unlock it and should freely coast.

[351fifty]

If you shift into neutral while coasting and same result then it should not be the trans

[WorkDog]

Good suggestions guys! Sorry should have specified that its a auto tranny. But I will try shifting it into neutral down a hill. Should have thought of that myself... thanks dudes.

[Diesel_brad]

Check the brakes anyway

[alberta 7.3]

Check the wheel alignment to make sure the front isn't toe-in and scrubbing the tires.

[clatterindiesel]

Does it feel sluggish on acceleration? Possibly EXhaust back pressure valve stuck. Is that 10mpg hand calculated? Or a guesstimate?


Sent from AutoGuide.com Free App

[gabegoforth]

My Ts Chip makes mine feel like its got a exhaust brake some times. I never have stuck a camera underneath the hood to monitor that valve to see if it closes all the time when I let of the accelerator. They could easily be programed to be used as a Jake.

[JD3020]

My truck is the same way, most hills i come to it'll hold speed or slow down, when everybody else is on the their brakes. Steep hills it will gain speed. I think my brakes are dragging a bit, and im not running my tires at full pressure.

But i think its also to do with rotating mass and areodynamics. My moms 05 Suburban will coast all day long, and i'm honestly surprised i haven't gotten a speeding ticket yet cause my truck will slow its self down, whereas the Suburban just keeps going at the same speed. I've came into town(25mph) doing 50 when i'm used to my truck being slowed down to 30 in the same distance driving the same ways.