Confirming some towing questions

[Bow_Tied]

Hi there, new to GMTs, new to 5.3L engines, but not new to towing.

My towing plan always involves a loaded trailer that is ~75% of towing capacity or less to allow for some safety factor. My plan includes also adding a plate style trans cooler.

Reading items on the net and also reading the Owners Manual I have a couple of questions:

The manual indicates that with the 5.3L 5 passenger 4x4 w/3.42 gears the towing capacity is 6,000lbs - which conflicts with some other on-line things I have read. Can I trust the manual?

The manual indicates that towing in OD is ok unless the trans is shifting a lot. Can I trust the manual? Some on-line sources say yes, some say tow in 3rd gear only.

If I tow in OD will the DOD be kicking on and off or does it "know" to stay off?

If I tow in 3rd the DOD is automatically disabled, correct? I don't care too much about fuel economy while towing, but don't want to throw away economy needlessly. Trans health is of course more important.

Has anyone had an electric brake controller installed by the dealer? Recommended or overpriced? I want a quality unit with the built in gyros for load sensing/proportional braking.

Adding an electric brake controller - I scanned a number of posts here but what I am looking for is the wiring connection points under the dash- diagram and pictures. Perhaps I missed this post, so a link is appreciated.

How does the auto leveling suspension work with load distribution hitches? Do they play well together? What do I need to know? Again, apologies if I missed this post - link appreciated.

Sorry for the long list. Any/all answers appreciated.

 

[djthumper]

Add the cooler, you won't regret it.

What are you seeing online for capacity? 6000 LBS is fairly safe and have hauled it behind my 4.2 with 3.42.

I have towed in OD unless it is constantly hunting or if I am up near the load limit.

I can't comment on the AFM switching as I only have the 4.2 in my Trailblazer and haven't hauled much with my new Silverado.

I would not have a dealer install the brake controller... Maybe an RV dealer.

I thought there was a posting on ow to do it on this site, I just installed mine about 18 months ago. I will look for a link, it may be to the old site or on ORTB, BartonMD did the original article.

I can't answer on the auto level as I don't have it.

 

[Bow_Tied]

Thanks for the reply, dj. That helps give a perspective on things.

 

[Mooseman]

The wiring for the brake controller is under the left side of the dash. 4 blunt cut wires taped up. Not that difficult to install.

How to install an electronic trailer brake controller

This is my first article submission and is only a draft so ........here goes.. This is a pretty easy DIY compared to many things. Time: 2 hours ( tops ) Difficulty: Easy to medium easy Tools: Philips screw driver, wire strippers, solder gun, drill, lighter Supplies: EBrake Controller unit...

gmtnation.com

When hauling heavy, I always tow in 3rd. Found that OD just created more heat and shifting for the little economy you would get. Mind you, this was with my previous ride, a 2002 TB EXT with the 4.2. Haven't towed with the 5.3 yet so I don't know how AFM (or DOD) will react. It should know that you're pushing the gas more to keep the speed up. Lots of guys get it permanently disabled via a tune since it has been a problematic system (oil consumption and failures).

I also can't answer on the auto level since neither of my trucks have it. Anything in the manual about it?

 

[Bow_Tied]

Thanks for the link, Moose. I will have to hunt for those wires when I get some time.

I am leaning toward using 3rd for towing, especially since I have the 3.42s so the revs won't be too bad on the freeway if I am going slow.

I did not find anything in the manual in the towing section about the air suspension. Might be in a different section....

As to the DOD being problematic - there are thousands and thousands of 5.3Ls on the road - is this an issue for all of them or only in our models? Does running synthetic help? I was thinking of switching to Mobil 1.

 

[Mooseman]

I have limited experience with it myself but one guy here reported lifters collapsing on him. Another had high oil consumption, which was a problem with the early models with this system. You could ask a dealer to check their system if it was fixed under warranty. Mine has 155k and I find the oil use pretty high. I don't like the feeling when it kicks on and off. It's supposed to be seamless but I can feel it.

 

[Bow_Tied]

Good to know thx.

 

[Instrumental]

I will chime in on the oil consumption. My 5.3 is an oil hog, and more so when towing and on the highway. I keep a close idea on the oil level pretty regularly, and double check when doing a long tow. It's not unusual to add a quart after a few hundred miles of highway towing.

I go back and forth on D v 3. If I've got a lighter load and it's fairly level, I'll go with D and keep an eye on the shifts and the temp (love Torque). A heavier load I just go straight to 3.

I have read that it's advisable to set the leveling bars with the key off, so it can't adjust until you've got them set. Not sure about details on that, haven't done it myself.

I have thoroughly enjoyed towing with my 9-7x, granted my previous experience was a Villager and an Aztek, so the upgrade was significant.

 

[Denali n DOO]

I have 3:73's and don't tow lots of weight but always tow in 3rd. I have the rear bags and believe the max tongue weight is 400 lbs, not sure how w/d hitch affects that as I've never used one. When my oem bags crap out I will convert to coil springs and install an Air Lift 1000 pkg if more tongue weight is needed.

I don't have much to say about the stupid DOD system and ridiculous random oil usage, If I ever get the pcm of nc tune the DOD will be turned off. I currently drive in 3rd most of the time to keep DOD turned off.

My first motor let go at 89,000 km while pulling a trailer with 2 Ski Doo's in it. I had done a few 1000 km trips north pulling the trailer and it only had 1 liter of oil left in it when it blew. Of course I get the "turn engine off now" display just as the motor starts breaking apart, no warning at all. No low oil level light on these. As mentioned above keep an eye on the oil level especially when towing.

 

[Chickenhawk]

Here is my view on towing with OD. When towing, one needs to keep the RPMs in the best power band regardless of gear and just live with the mileage that results. Saving a few cents per mile is false economy if one overheats the transmission. Because of the design of transmissions, a slight increase in temperatures significantly shortens the life of the transmission, and I wouldn't want to take any chances.

Basically, if I am pulling anything over about 1500 pounds, I always tow in 3.

But there is always one way to find out for sure. If you are on level ground with an easy tow and are tempted to try OD, just slip it into OD, wait for the shift and the lockup converter to engage and feel the physical position of the gas pedal. Then slip it into 3, and note if the pedal is now higher or lower to maintain the same speed. You will find out that in most cases (over about 1500 pounds) the pedal is less depressed. This indicates it is pulling easier in 3 than in OD.

Just remember that higher RPMs are not bad, especially when they put the engine more into its power band. While it is tempting to want the best mileage (and lower oil consumption on the 5.3) while towing, it may shorten the life of the transmission.

Note that this trick to see which gear gives you less gas pedal to maintain the same speed has been a common trick of tow-ers for many years. It does not always work quite so well with some of the newer electronic throttle position sensors, but try it and see if it works.

This is how I determined that 1500 pounds is about my upper limit for towing in OD with my 4.1. (Even under that arbitrary number, any slight uphill or crosswind, and I would almost always tow in 3 anyways.)

 

[IllogicTC]

I have 3:73's and don't tow lots of weight but always tow in 3rd. I have the rear bags and believe the max tongue weight is 400 lbs, not sure how w/d hitch affects that as I've never used one. When my oem bags crap out I will convert to coil springs and install an Air Lift 1000 pkg if more tongue weight is needed.

I don't have much to say about the stupid DOD system and ridiculous random oil usage, If I ever get the pcm of nc tune the DOD will be turned off. I currently drive in 3rd most of the time to keep DOD turned off.

My first motor let go at 89,000 km while pulling a trailer with 2 Ski Doo's in it. I had done a few 1000 km trips north pulling the trailer and it only had 1 liter of oil left in it when it blew. Of course I get the "turn engine off now" display just as the motor starts breaking apart, no warning at all. No low oil level light on these. As mentioned above keep an eye on the oil level especially when towing.

On the subject of DOD and oil issues, it should be noted that the DOD engines have a second oil filter, built-in. I believe it's at the back (and inside) of the block where the oil comes up to go to the valve trains; it's something more along the lines of a screen or mesh that can be cleaned and popped back into place, and we've had a member or two here before fighting oil pressure issues where the clogging of this secondary filter turned out to be the problem. Just something to keep in mind when monitoring the oil pressure. As for oil loss.... not sure, I'm a 4.2 owner!

 

[Bow_Tied]

Good feedback, thanks all!

 

[RedEnvoyDenali]

Add the cooler, you won't regret it.

What are you seeing online for capacity? 6000 LBS is fairly safe and have hauled it behind my 4.2 with 3.42.

I have towed in OD unless it is constantly hunting or if I am up near the load limit.

I can't comment on the AFM switching as I only have the 4.2 in my Trailblazer and haven't hauled much with my new Silverado.

I would not have a dealer install the brake controller... Maybe an RV dealer.

I thought there was a posting on ow to do it on this site, I just installed mine about 18 months ago. I will look for a link, it may be to the old site or on ORTB, BartonMD did the original article.

I can't answer on the auto level as I don't have it.



with a couple of exceptions and additions:

I have a 5.3 like you, I tow 4500 to 5000 lbs for about 1000km a year for my heaviest tow.

i don't use electric brakes for the trailer since it has surge disc brakes. i also tow in OD but the terrain is fairly flat if the tranny went searching i would downshift to 3rd. I would think the RV dealer would be a good choice for the brake controller.

I use a Tru-Cool 4589 in my Denali, love it. I changed the tranny fluid to Amsoil synthetic and then changed that along with filter around 50K. I did all this when i installed the cooler. Notice i said change not FLUSH, won't do that. To make it easier I installed a drain in the pan so that saves time and mess.

I have never felt my DOD kick in or out so no comment on when it works, a light would be the only way of telling but no GM didn't put that in.

I have air bags on my Denali. Some choose to replace with springs, i choose to replace they bags when they weathered and cracked. Love the way it works, as soon as I put weight on the hitch the bags adjust the rear end higher and of course drop it down when the trailer is gone. All in all i am happy with the bags.

good luck on the tow, since you have experience just let that work for you and you should not have any trouble.

 

[Bow_Tied]

Thanks RedEnvoyDenali - I have seen that specific cooler recommended a couple of times now, so it will be on my list to investigate. I also need to determine best mounting position. Any suggestions?



The manual indicates 400# tongue weight, 900# with load distribution. Normally I would I set the load distribution bars so the ride height was the same with/without the tongue load. The manual even states this. However would the airbag system not defeat me on this? Unless I put the tongue on just after shutting the truck off?

 

[Mooseman]

From the OS, this is how I mounted mine.
http://forums.trailvoy.com/showpost.php?p=773038&postcount=42

 

[Bow_Tied]

Looks like a nice clean install, Moose. I did a similar install on my Jimmy ZR2 on the passenger side. Good to know there is room in there.

 

[Bluto4x]

When towing my camper, I let the bags level out but then turn the key off until everything is hooked up. There shouldn't be too much readjusting if your load bars are set right. And I run in 3rd gear unless I'm cruising on a flat spot on the highway. Since I live in NE PA, that's less frequent. I installed a B&M 70264 cooler with a Hayden trans line adapter (397) and a Tekonsha P3 brake controller. And had a helluva lot of fun last year. My Rainier has the 4.2 and 3.73 gears so I can help you on that front.

 

[Bluto4x]

Also while I'm thinking of it, be sure to check your tranny lines for corrosion. Tranny lines are a lot cheaper fix than a tranny rebuild.

 

[RedEnvoyDenali]

Thanks RedEnvoyDenali - I have seen that specific cooler recommended a couple of times now, so it will be on my list to investigate. I also need to determine best mounting position. Any suggestions?



The manual indicates 400# tongue weight, 900# with load distribution. Normally I would I set the load distribution bars so the ride height was the same with/without the tongue load. The manual even states this. However would the airbag system not defeat me on this? Unless I put the tongue on just after shutting the truck off?

From the OS, this is how I mounted mine.
http://forums.trailvoy.com/showpost.php?p=773038&postcount=42

Thanks Mooseman for posting my install. i couldn't pick that pic up and post here. That install worked really well it only needed very minor amount of trimming in the upper left hand corner and put the plumbing right near the pipes on the left hand side of the radiator.

 

[Mark20]

I'm towing my ~5000 lb camper with my 2011 Silverado. I usually run the transmission in 5th until the temperature gauge reaches its normal just to the right of straight up and down and then go to D. I do know DOD will not kick in until the engine reaches a certain minimum temperature.

I have had DOD occasionally kick down to four cylinders while towing in D. Usually a down grade where gravity is giving me an assist but sometimes on flat ground. The Silverado can get some decent mileage on the highway but not when towing.

Its good to know about that secondary oil filter.

 

[Mooseman]

Thanks Mooseman for posting my install. i couldn't pick that pic up and post here. That install worked really well it only needed very minor amount of trimming in the upper left hand corner and put the plumbing right near the pipes on the left hand side of the radiator.

I hope you didn't think I posted that as saying it was mine . I meant to say " here's the method I followed...". I didn't make the connection between the old and new you here. As the owner of the original pic, you could post it here.

 

[RedEnvoyDenali]

I hope you didn't think I posted that as saying it was mine . I meant to say " here's the method I followed...". I didn't make the connection between the old and new you here. As the owner of the original pic, you could post it here.

Nope i took it exactly the way you said, saw the pic and liked the install. thanks for posting it, tried once before and it wouldn't go for me, not sure why but it didn't.

 

[Mooseman]

Here you go. As the owner of the pic, I assume you permit me to post it here and it is identified as such.

 

[jfkmk]

Here you go. As the owner of the pic, I assume you permit me to post it here and it is identified as such.

Tranny Cooler.jpg

I installed my trans cooler in the same place. In fact, I think I saw this original post and used it as a guide. It was an easy install with just a little cutting with a dremmel. The only other thing I did was move the temperature sensor because I was tired of being told it was 100 degrees out in the middle of winter.

As an aside, I tow a 3500# camper with my i6 and get a steady 12 mpg at 60-65 mph in 3rd gear. I actually increased my mileage by using 3rd instead of D.

 

[RedEnvoyDenali]

Here you go. As the owner of the pic, I assume you permit me to post it here and it is identified as such.

Tranny Cooler.jpg

You most certainly have my permission, and thanks for adding the tag, I would not know how to do that with this damn computer. LOL

 

[{tpc}]

Been awhile for me on here, but saw this and thought maybe my experience might help? Anyways, after the first tow of our camper with my wifes 4.2 envoy, I upgraded my car to 07 tahoe with the 5.3. The 4.2 could do it, but it was so much more comfortable in the tahoe...and I probably should have listened more to folks here about that, but I digress. I will note that I love my tahoe much more than my previous car especially with winter here, and even if the gas mileage is worse.

So my experience with the afm/dod stuff is that it will go into v4 mode mode if towing in O/D even with the tow/haul button enabled. Also, depending on the grade, the trans will hunt some, and I towed enough this past summer that I got tired of that pretty quickly, so now I do tow in 3 all the time. I don't quite remember if the afm/dod stuff engaged in 3rd, but I don't think that it did.

As for oil consumption, the only time I've had a problem is as I am trying to approach 6k miles between oil changes. Typically I try to do somewhere in the 3-5k range if I am towing a lot. The longer I let it go, the worse it can get, but I've never seen it more than 1/2 to 3/4 of a quart low. For a truck that has 190k miles on it now, I can deal with that.

I have had an issue with the oil pressure sending unit, and had to replace it. I believe this is where that second "filter" or screen is located, directly below that unit in a small little tube type area. I've watched the videos online, and for the life of me, I have no idea how one can remove that, unless you have the whole top of the engine off or something, due to its location. It was enough work getting the old oil pressure unit out and the new one in, while having to do it blind, that I gave it one small attempt and then decided the screen would not get cleaned this time.

As for the trans cooler, it is a must. I went with a direct oem cooler, and it dropped the temp considerably. To the point where I just check it every so often. Its pretty nice, just bolted right on, came with trans lines etc, and was fairly inexpensive. The first one I received came with a improperly bent line so they just sent me a whole kit to replace it, and ups never asked for the bad one back so they must have just ate the claim...so now I have spare parts lol.

For the brake controller, I went with the teknosha p3 because I found a good deal on one on craigslist. Install is easy, but I would be very careful to make sure you mount it squarely and securely, as mine seems a bit more sensitive if knocked out of alignment by my leg or something. Its easy for me to tell, because I can see on the screen the change in voltage going to the brakes, as well as the feel of the trailer grabbing harder or softer. But I wouldn't spend extra money to have it installed, there should be a pigtail under the dash, and the unit should come with instructions on how to wire it up.

When towing I get a pretty constant 9-10mpg, 16 mpg when not towing. That may be a little low than some other v8's but it seems to jive with what I've heard from others I've talked with.

 

[Bow_Tied]

Moose / RedEnvoy - thanks for the pics!!!! Truly worth a thousand words.

tpc - that's some good real world experience, thank-you. You mentioned that you got an OEM trans cooler for your Tahoe. Do you (or anyone) know if a OEM external trans cooler was available for the TB/Envoy?

 

[Mark20]

Probably not since GM very prominently said there was a trans cooler but it is in the radiator. Its pretty beefy but an external one will help.