rxhermo: i own a 2001 5.9 24v 2500 with one ton everything underneath, my
situation is when I tow my 5th wheel (12800lbs.) it cycles between gears.when climbing long hills. The vehicle is well mainained, but this is bothersom to me. any suggestions as to how to solve the issue? The truck is great and if I can believe the onboard computer I get around 32-34 mpg on the freeway. It is an auto tranny.

 

First post - - hey, welcome to the forum. Mostly a good bunch around here - - you do have to watch out for a couple of wierd ones.

My first comment is you either transposed the numbers on your mileage or your computer is drastically wrong. If you truly get those kinds of numbers on mileage, I will sell my 3rd gen and buy one just like yours. Fill the tank, take the odometer mileage down, drive the tank down, refill and manually compute. Try about 21 if you are careful.

Now to the cycling issue on the tranny. Any time you are climbing and find the tranny cycling, you need to drop it out of fourth down into third. Do not let it sit there and cycle - - not good at all for the tranny. All of us, manual and auto, have to help the tranny once in a while and drop down a gear or two when towing lots of weight.

Bob

 

You're killing your transmission by letting it hunt for gears. If its hunting back and forth its making heat,heat it probably the biggest killer of a tranny.

Alot of guys have a misconception that a diesel doesn't need to downshift. I swear they think its a hit to their manhood if they can't pull 15,000lbs up an 8% grade and have their truck stay in O/D. Transmissions have more than 1 gear for a reason.

Like was mentioned,drop down into 3rd and let the rpm come up. I guarantee it will pull better. Don't be afraid of rpm with the Cummins. It will run at 3000 rpm forever.

 

rxhermo:ILLED THE TANK IN MY HOME TOWN OF TEMPLE CITY CA. CAN MAKE IT TO TULARE ON LESS THAN A QUARTER TANK INCLUDING DRIVING ROUND THE TOWN. CUMMINGS REPLACED THE ORIGINAL ENGINE CHIP WITH THEIR OWN BACK IN 2001. BEEN GETTING GREAT MILEAGE SINCE I BROKE THE TRUCK IN. I CAN ONLY GO BY THE FILL AND DRIVE AND FILL METHOD OF VERIFICATION. THANKS FOR THE INFO ON THE CYCLING .

 

Your calculator is broke no way you get 32-34MPG