Realistic towing expectations with the 5.3L

9c1fanatic · February 26, 2020

Good evening gals and guys,

I've been reading this site for about a year now and soaked up as much information as I can. I've finally squared away all my other life priorities and looking to buy a used k2XX Silverado 1500 as a back up daily driver but mostly for my plethora of outdoor recreation interests. Lifetime GM car owner but only ever owned one truck which I still have and plan to keep, a GMT400 1500 with a 5.7L 5speed combo. This truck is/has been great but I feel like I'm driving on borrowed time when I use it to pull my travel trailer which seems to be on the heavy side for its 24 foot length. Its 5900 empty and ranges between 6500-7000 pound depending on how long of a trip I'm taking. I've been towing it for a year with the GMT400 but the hilly area I live in Texas makes this less than an enjoyable experience. I knew this would be the case from the beginning as my truck has 3.08 gears and is rated lower because of it.

As I have started to look at 2014-2018 Silverado crew cabs, I am finding the overwhelming majority of these trucks around here are equipped with the 5.3L/6L80E/3.42 combo which rates the max trailer weight in the 9100-9600 lb range depending on truck configuration. The 5.3L NHT optioned trucks (max towing) with the 5.3L/6L80E/3.73 combo pop up every now and then but are difficult to find and sell quickly before I can get to them. I might consider an LTZ with a 6.2L but the price would have to be really good because the LT trim is what I really want in a truck. (Not a huge fan of leather seats, driver assistance technology etc more expensive LED lighting etc)

The payload of my current GMT 400 truck is slightly more than the average K2xx crew cab and I'm doing fine in that department. Mainly just wondering if guys on here that tow, specifically with travel trailers (due to the wind resistance factor) feel their 5.3L six speed/3.42 truck is sufficient for most of their towing experience. I have towed the trailer one time with a 2019 T1 Sierra 5.3L 8L90E 3.23 and it exceeded my expectations however that powertrain really isn't an option for the trucks I'm looking at. I'm really curious how much different a 3.42 6 speed truck would be with the rear gearing advantage but transmission disadvantage.

95 percent of my towing is in Texas with towing in the Rockies once a year (I currently borrow a Ram 2500 cummins for this once a year trip). I'm not looking to win an uphill drag races or hang with diesels, I just want to be able to have the ability to drive the thing at 65-70 MPH on Texas highways without really overworking the truck.

Any of you guys tow a travel trailer with the 5.3L/6L80E/3.42 combo with stock size tires? What are your impressions good or bad?

Edited February 26, 2020 by 9c1fanatic
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CamGTP · February 26, 2020

I don't have a travel trailer but I've towed an open car trailer with car on it. Talking somewhere in the 5,500-6,000lbs total weight.

You feel it back there but it's no issue with my truck. I have the same combo you are looking at, 5.3/6L80e with 3.42 gearing. I wouldn't have any issue towing what you have with this type of truck, it'll handle it no problem.

One suggesting I do have is that with whatever truck you get in the K2XX platform, is that you "remove" the factory transmission cooler line thermostat. It's just a simple mod to do. It will help lower transmission temps by 30-40 degrees.

durandetto · February 26, 2020

I have no personal experience, but I have a cousin and buddy that do and they don't complain about not having enough truck. I do however have a old heavy car hauler and while I haven't towed with a car on it yet. I've had a good amount of weight on it and it still has plenty of power. Easily catch myself going 80 on the highway. My truck does have aftermarket exhaust and a tune and I usually run e85 so there's an extra bump in power. I think your biggest problem will be trans Temps. Might need to make some mods to keep them below 200 down south in the heat. I towed my trailer loaded with quads and other stuff in the 90 degree heat 2.5 hours and my truck managed to stay below 200, but I've heard of others on here pushing well past 200. Running hot consistently will shorten the life of your trans.

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9c1fanatic · February 26, 2020

Good point guys, I read up on the trans deal. The fence seems to be split about reverse the order of the parts in the t stat or removing them altogether and tapping for a threaded plug. Curious, one thing I cant seem to figure out is do all k2xx half tons have an external transmission cooler (not talking about the one integral to the radiator tank) or is that just on certain trucks?

Grumpy Bear · February 26, 2020

58 minutes ago, 9c1fanatic said:

Good point guys, I read up on the trans deal. The fence seems to be split about reverse the order of the parts in the t stat or removing them altogether and tapping for a threaded plug. Curious, one thing I cant seem to figure out is do all k2xx half tons have an external transmission cooler (not talking about the one integral to the radiator tank) or is that just on certain trucks?

No. My 2015 has only the tank cooler.

I flipped the pill in mine and it took over 40 degrees out of the fluid heat on a 100 F day. You can plug it as well. The pill cost is zero.

1 hour ago, 9c1fanatic said:

I just want to be able to have the ability to drive the thing at 65-70 MPH on Texas highways without really overworking the truck.

Give it enough gear and you could tow the weight of a mountain at 70 mph with an old inline 292 I6 and not over work it. Often the motor is more comfortable with the load than the driver.

Question you should be asking is; can you stop it? School buss pulls out in front of your 13,000 pound combine weight rig while your doing 70 mph. Can you stop it in time? It's just a question. Almost everyone I know out drives their brakes.

durandetto · February 26, 2020

Give it enough gear and you could tow the weight of a mountain at 70 mph with an old inline 292 I6 and not over work it. Often the motor is more comfortable with the load than the driver.

Question you should be asking is; can you stop it? School buss pulls out in front of your 13,000 pound combine weight rig while your doing 70 mph. Can you stop it in time? It's just a question. Almost everyone I know out drives their brakes.

Brakes can be upgraded for minimal cost or you could go all out and put brembo or wilwoods on it. The newer trucks are much better at stopping than the old. With a good high performance metallic pad and high quality slotted rotor you can get better braking on a budget. I would imagine his newer camper would have dual axle brakes that could stop both the truck and trailer by itself. My car hauler has no brakes and my truck does a decent job stopping it and I've only upgraded the front brakes so far.

Moral of the story is I think he'll be good pulling his camper with the trucks he's looking buy. Worst case scenario he'll need a couple, affordable mods to make the task more pleasant. He could even re-gear it if he thinks it's not good enough. I've seen older 1500s pulling 5th wheels with boats on the back, not that I would ever recommend that. I have customers that pull 5th wheels with half tons with no issue.

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truckguy82 · February 26, 2020

with modern v8’s, hp isn’t the weak link

literally buying a box truck with 182hp and an 18klb gvrw

Edited February 26, 2020 by truckguy82

ray2005 · February 26, 2020

I don't have the combo you are looking at, I have the nht package (5.3, 8 speed, 3.42). I tow a 32', 8000lb loaded trailer with no issues. The "mountains" in PA are not the rockies however I haven't had any issues. I wasn't doing 65 but 50-55 and I don't think the transmission temp went over 200.

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Nanotech Environmental · February 26, 2020

9 hours ago, 9c1fanatic said:

Good evening gals and guys,

I've been reading this site for about a year now and soaked up as much information as I can. I've finally squared away all my other life priorities and looking to buy a used k2XX Silverado 1500 as a back up daily driver but mostly for my plethora of outdoor recreation interests. Lifetime GM car owner but only ever owned one truck which I still have and plan to keep, a GMT400 1500 with a 5.7L 5speed combo. This truck is/has been great but I feel like I'm driving on borrowed time when I use it to pull my travel trailer which seems to be on the heavy side for its 24 foot length. Its 5900 empty and ranges between 6500-7000 pound depending on how long of a trip I'm taking. I've been towing it for a year with the GMT400 but the hilly area I live in Texas makes this less than an enjoyable experience. I knew this would be the case from the beginning as my truck has 3.08 gears and is rated lower because of it.

As I have started to look at 2014-2018 Silverado crew cabs, I am finding the overwhelming majority of these trucks around here are equipped with the 5.3L/6L80E/3.42 combo which rates the max trailer weight in the 9100-9600 lb range depending on truck configuration. The 5.3L NHT optioned trucks (max towing) with the 5.3L/6L80E/3.73 combo pop up every now and then but are difficult to find and sell quickly before I can get to them. I might consider an LTZ with a 6.2L but the price would have to be really good because the LT trim is what I really want in a truck. (Not a huge fan of leather seats, driver assistance technology etc more expensive LED lighting etc)

The payload of my current GMT 400 truck is slightly more than the average K2xx crew cab and I'm doing fine in that department. Mainly just wondering if guys on here that tow, specifically with travel trailers (due to the wind resistance factor) feel their 5.3L six speed/3.42 truck is sufficient for most of their towing experience. I have towed the trailer one time with a 2019 T1 Sierra 5.3L 8L90E 3.23 and it exceeded my expectations however that powertrain really isn't an option for the trucks I'm looking at. I'm really curious how much different a 3.42 6 speed truck would be with the rear gearing advantage but transmission disadvantage.

95 percent of my towing is in Texas with towing in the Rockies once a year (I currently borrow a Ram 2500 cummins for this once a year trip). I'm not looking to win an uphill drag races or hang with diesels, I just want to be able to have the ability to drive the thing at 65-70 MPH on Texas highways without really overworking the truck.

Any of you guys tow a travel trailer with the 5.3L/6L80E/3.42 combo with stock size tires? What are your impressions good or bad?

My personal rule of thumb when towing is don't exceed about 75% of rated tow weight. That's just me. It gives more margin of safety, especially on bumper pull trailers. That trailer seems pretty heavy for a 24'. Have you dragged it across a scale to verify?

The k2xx's are 10x the truck the old GMT400s were, IMO. Better in every aspect by far.

Edited February 26, 2020 by Nanotech Environmental

9c1fanatic · February 26, 2020

Yeah I understand the point being made but I just threw the speed out there for max scenario for the common use I would see. I dont plan on driving that speed with the trailer in any situation where it was possible for a school bus, or any vehicle for that matter to pull out in front of me. The trailer does have dual axle brakes and surprisingly my GMT400 stops it pretty well considering how poor the brakes are on that generation of trucks. K2XX brakes will be a massive improvement.

That is a combo, I've never seen on the K2XX. Im guessing your truck is an LTZ or Highcountry to have the 8speed and 5.3L?

9c1fanatic · February 26, 2020

11 minutes ago, Nanotech Environmental said:

My personal rule of thumb when towing is don't exceed about 75% of rated tow weight. That's just me. It gives more margin of safety, especially on bumper pull trailers. That trailer seems pretty heavy for a 24'. Have you dragged it across a scale to verify?

The k2xx's are 10x the truck the old GMT400s were, IMO. Better in every aspect by far.

Yeah that's why I was asking. I would be getting close with a loaded trailer to that 75-80% rule. I have weighed the trailer. Total emptry weight (with residual water in the lines) was 5884 which was really close to the UVW rating listed on the trailer. When hooked up to the truck, hitch weight was just over 600 lbs. Its a Grand Design and when I was shopping around I noticed their trailers typically weigh more than similar size trailers from the competition. I think it has to do with the way they are built, materials etc. I will tell you that the weight to size ratio of this trailer makes it pull really well. No issues with wind so far or even passing semi trucks even with the old GMT 400 which is a much lighter truck than a K2XX 1500. My truck weighs 4450 lbs with me in it!

ray2005 · February 26, 2020

Yeah I understand the point being made but I just threw the speed out there for max scenario for the common use I would see. I dont plan on driving that speed with the trailer in any situation where it was possible for a school bus, or any vehicle for that matter to pull out in front of me. The trailer does have dual axle brakes and surprisingly my GMT400 stops it pretty well considering how poor the brakes are on that generation of trucks. K2XX brakes will be a massive improvement.

That is a combo, I've never seen on the K2XX. Im guessing your truck is an LTZ or Highcountry to have the 8speed and 5.3L?

Yeah it's an LTZ. I guess the LTs come with 6 speed and 3.73.

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9c1fanatic · February 26, 2020

3 minutes ago, ray2005 said:

Yeah it's an LTZ. I guess the LTs come with 6 speed and 3.73.

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Yeah if its an LT with NHT its the 6 speed and 3.73

Nanotech Environmental · February 26, 2020

5 minutes ago, 9c1fanatic said:

Yeah that's why I was asking. I would be getting close with a loaded trailer to that 75-80% rule. I have weighed the trailer. Total emptry weight (with residual water in the lines) was 5884 which was really close to the UVW rating listed on the trailer. When hooked up to the truck, hitch weight was just over 600 lbs. Its a Grand Design and when I was shopping around I noticed their trailers typically weigh more than similar size trailers from the competition. I think it has to do with the way they are built, materials etc. I will tell you that the weight to size ratio of this trailer makes it pull really well. No issues with wind so far or even passing semi trucks even with the old GMT 400 which is a much lighter truck than a K2XX 1500. My truck weighs 4450 lbs with me in it!

What is the tow cap on that GMT400? IIRC they were only about 6000-7000 or so, but I could be wrong.... The K2xx with a 5.3 will really pull that trailer nicely and has easily 2x the braking power, plus the trailer brakes.

9c1fanatic · February 26, 2020

1 minute ago, Nanotech Environmental said:

What is the tow cap on that GMT400? IIRC they were only about 6000-7000 or so, but I could be wrong.... The K2xx with a 5.3 will really pull that trailer nicely and has easily 2x the braking power, plus the trailer brakes.

I know Im about to get blasted here but in total transparency here it is:

My 91 with its cab configuration and engine option is 5500 with 3.08s, 6500 with 3.42s and 7500 with 3.73s. I'm way under my weights in payload, axle weight ratings and GCWR. I have upgraded the engine to a more powerful L31 vortec motor compared to the old 210hp LO5 and have exhaust mods. I know I'm over max trailer weight but my logic (however flawed it may be) is that from a safety standpoint, my truck is no different than a 3.73 geared truck (same suspension, weight, brakes etc). I have upgraded the tires and shocks and have a really good WDH. That being said, I only use the truck to pull within about 100 miles or less and even then, I have to carefully plan. I keep the trailer as close to empty as I can and have to make sure I avoid situations where I might have to reverse up hill. Its not ideal, but the forward gearing of the NV3500, it does fairly well and I borrow other trucks when I have to go farther than 100 miles.

From the beginning this was temporary. I bought my trailer first knowing I would match a truck to it one day. I've been wanting a K2xx truck for a while now but needed to get some things in order first. Now im ready and on the hunt.