Towed uphill new truck not sure if truck response is normal

[Tedmonster]

Hi I recently bought a gas 2013 Sierra 2500hd. Low miles has towing package. Just today I bought a 4500lb dump trailer and was taking it home. I turned off tow/haul on the main flat roads but then came to a hill a few hundred yards long. I never put it back into tow mode and started climbing the hill and got to about 25mph but I wanted to see how the truck handled some more effort so I started accelerating but no response. Alittle more no response. At this point I have it a little more and the rpms suddenly jumped way up to about 5k at which point I let off. My question is this normal for the 6.0? Also should I be concerned at all about damage or wear to the transmission or engine from the sudden excessive jump in RPM uphill with trailer. Thanks 

[Jsdirt]

Without being there and seeing exactly what is happening, I can't really tell if it just downshifted (doubtful at 25 mph), or you lost 1st gear for a second there. Coincidentally, my tranny just failed in my  Silverado 1500 after just 103k miles. Only the 3rd transmission failure I've ever experienced in 30 years, and at the lowest mileage ever. They don't build stuff like they used to.

 

But back on topic -  when it jumped to 5k, was it still pulling, or did it act as if it was thrown in neutral for a second? If the latter, check your fluid level HOT, and on a reasonably level surface - should be right in the center, or close to the top of the crosshatch pattern after working it for a bit to get things nice and hot. If that checks out, you're going to need a stretch of straight road with no traffic or houses to do a full-throttle run through 3rd gear unloaded, and see how she shifts. If at any time it feels like it shifted into neutral on its own, the tranny is done for. Rebuild or replace time.

Edited September 22, 2020 by Jsdirt

[Tedmonster]

21 minutes ago, Jsdirt said:

Without being there and seeing exactly what is happening, I can't really tell if it just downshifted (doubtful at 25 mph), or you lost 1st gear for a second there. Coincidentally, my tranny just failed in my  Silverado 1500 after just 103k miles. Only the 3rd transmission failure I've ever experienced in 30 years, and at the lowest mileage ever. They don't build stuff like they used to.

 

But back on topic -  when it jumped to 5k, was it still pulling, or did it act as if it was thrown in neutral for a second? If the latter, check your fluid level HOT, and on a reasonably level surface - should be right in the center, or close to the top of the crosshatch pattern after working it for a bit to get things nice and hot. If that checks out, you're going to need a stretch of straight road with no traffic or houses to do a full-throttle run through 3rd gear unloaded, and see how she shifts. If at any time it feels like it shifted into neutral on its own, the tranny is done for. Rebuild or replace time.

It definately didn’t feel like it went into neutral. It kept pulling and picked up a bit I just was concerned with how abrupt and fast the rpms shot threw the roof. Thanks for your reply. Does this change your view? I’m used to pulling with work trucks which are always been diesel so I didn’t know if the gas 2500 just runs like that?

Edited September 23, 2020 by Tedmonster

[CamGTP]

Non issue.

 

What you did is no different than going 25-30mph and just flooring it. It's going to downshift and zing the rpm up way up into peak horsepower and start pulling.

 

If it was an issue they would program it to not allow for it because it would engine damage. But it's not a problem at all and it's working as it should. Diesel engines don't rev like gas engines, they are much heavier in both mass and rotating assembly weight and make way more torque at any given rpm compared to a gas engine.

Edited September 23, 2020 by CamGTP

[Jsdirt]

If it was still pulling, non issue like Cameron said. You must've been in 2nd gear for a while there.

[CamGTP]

I bet it did a 5th to 2nd downshift if it lugged that long without going down a gear(s).

[Jsdirt]

Wow, yeah, these newfangled trannys with 6+ speeds do all kinds of weird things I hear. I've only ridden in an 8-speed FCA product. The shifts were so mushy you couldn't tell they were happening - I had to watch the tach.

 

Those should be a real barrel of fun at rebuild time. I'm betting it will be cheaper to scrap the whole unit and buy another.

[Doug_Scott]

The 4L60E does that too.  Have a friend with a 2004 Sierra with 5.3 and the 4L60E.  If he leaves it in Drive when towing his trailer and comes to a hill on a road with an 80km/h speed limit it will begin slowing down, leaving the convertor locked up, until it gets to about 55-60km/h and it will unlock the convertor and downshift two gears into second.  Rpm will jump to over 4500rpm, and he just goes along with it and holds the gas pedal just short of WOT.  Next hill he remembers to put it into 3 before hitting the hill.  His truck has 3.23 gears.  The 4L60E in my 2010 Sierra with the 4.8 used to do that with no tailor but with the cruise on, at the same 80km/h would do the 2 gear downshift about 2/3 the way up the hill.  I had 3.23 gears as well.  After the change to 4.10 gears, no more issues with cruise on hills.  Not much change in mileage either.

[halld59]

I have a 2008 Silverado Max 6.0 Z-71 4 x 4 with a 4L70E transmission and I can positively tell you that your second gear has gone as my truck is at a local Chevrolet Dealership in Kenner, La waiting for the replacement transmission to come in. My truck has 489,674 miles on it and the current transmission has 212,028 miles.

[Jsdirt]

I think you're the only guy on the planet that got one built after 2006 to last that long. CONGRATULATIONS! You'd better go play the lottery now!