Hello, I have owned my 2003 F350 7.3 for a couple years now. It's all stock with 130,000 miles on it. It runs well. I just purchased a Toy Hauler. It will be close to 10k lbs loaded, and 7.5K unloaded and dry.I have no previous experience towing anything this heavy with my truck. What advice can you give me? When to use overdrive or not? Leave it in drive all the time or when or drop down to 1st or 2nd? I have only the stock gauges.

just this last weekend I replaced both front 4x4 hubs, dropped transmission pan and replaced filter. Installed mishimoto oil cooler. Replaced transfer case fluid. And today I'm doing the front and rear diff fluid. And if I have time before I head out this weekend the coolant as well.

What are your thoughts on a tuner for towing? I prefer to keep truck as stock as possible and dont want to sacrifice longevity or reliability. I will be pulling over mountain passes any direction I go pretty much.

 

gauges of some fashion are extremely useful if not mandatory IMO.
In stock configuration the biggest being trans temp. Heat kills these trannys.
the mishimoto one you mentioned is a great one.

These can be had the cheaper options are Hooking directly to a laptop or Bluetooth to phone and run super low cost apps. FORScan lite.

Have the up pipes been updated to bellowed design? If not make sure to check them as almost certainly will be leaking. Big losses of power and high egts.
I will let others describe how to tow in mountains. I suspect most would be in OD off...
make sure your brakes And controller are good to go . Try some hillier terrain locally to work out bugs.

tuners (hydra) sure turn it into a new truck but you will absolutely have to address gauges (including EGT), update the turbo wheel, and ensure those uppipes are updated to get the benefits.

 

If it stays in overdrive without frequent downshifts you can use overdrive. If it frequently shifts out of overdrive, turn it off.

Drop it down to 2 to control your speed downhill. Going uphill your right foot will make it shift to the appropriate gear. Just press the go pedal as much as you need to so that it maintains the speed that you want. You will probably meet some grades that with your foot on the floor you can't maintain the speed. Just go with it. The trans will go to the right gear and take care of itself.

My thoughts are that any tuner reduces longevity and reliability. If you want more go power and are willing to sacrifice reliability it's the way to go.

 

I will check into the UP pipes. But I'm guessing they are what came from the factory.

 

I just got back from a trip where I towed my 10k car hauler over a 7% 5000' mountain pass, I have the 6.0 Trans cooler and I don't think I ever saw my trans temp over 150. Engine Oil temp was up to 225.
Mine usually only gets hot if I have to do extended slow speed driving... I had to do a 10 mile detour once towing 15k at 5-10 mph, trans got over 210 that time. That was also before the 6.0 cooler.
I have a tuner and a Modified Trans Valve body, but I wouldn't recommend doing a tuner unless you also do an EGT guage, 4" Turbo back Exhaust and intake. Along with Brians suggestions about the uppipes.

I dislike the throttle response of my 2000 stock, so I really like the tuner. I'm usually in a 40 hp tow tune, so I don't think it's adding alot of fuel but the pedal is much less lazy. I think they are a bit more responsive on the later trucks.

In the mountains I like to keep my truck between 2000-2500 rpm and I'll manually shift it to do so.

Have you heard your fan kick into 'hot' mode?
If not I'd say put a new one on it, and a belt tensioner.

 

The transmission cooler will be the single, most important upgrade you can do for towing. Other than that get a good weight distribution hitch (anti-sway recommended) and make sure you are within axle ratings, hitch rating and payload rating and take it nice and easy in the slow lane. If you have 4X4, crew cab and SRW you might be surprised at how little payload you actually have.

 

Thank you for the great info guys. Took a drive with the new trans cooler and the stock analog guage showed a difference in temp. I do plan to get a proper aftermarket guage set. I will attempt to post a picture of my up pipes.

 

The previous owner of the trailer gave me the hitch setup with load bars and sway bar. I do have a 4x4 supercab. I was surprised to see how low the total weight rating was for our trucks.

 

The fan does kick on and off as it should. The belt looks decent but the mileage and age on it are unknown to me. I will replace the belt soon.

 

The stock gauge will be in the middle of the range when the trans is warmer than 50°F and cooler than 230°F. It won't move at all if the temps are between those two limits.

 

I tow tons through treacherous terrain.

• The stock transmission cooler has a reputation for letting people down, and the 6.0 transmission cooler for NOT letting people down.
• OBDII gauges are essential in today's world, particularly with a vehicle that has a lot of calendar flips behind it. FORScan, Torque Pro, and a few others are viable - but do your homework and ask questions (like a reliable OBDII Bluetooth adapter).
• With the OBDII gauges, many of the recommended gauges are covered, so all that's left are Exhaust Gas Temperatures and Fuel Pressure.
  • Our era of truck has flaws in the fuel delivery system, and this gauge might find power that you didn't know you were lacking - or not. Best to have it when pushing the demands on your engine.
  • EGT gauge, EGT gauge, EGT gauge. This could easily slide to the top of the list, but stock power puts a weak leash on this beast. One gauge covers one side of the engine - two gauges cover both. I've run into situations where a simple (and common) failure of the UVCH caused one side to run overly hot while barely moving - and the other side was almost ambient temperature. If the gauge is on the wrong side of a small failure - you can get lulled right into a big one. I run two EGT gauges - but some will say I'm OCD... which I can confirm.
• Tuning is fantastic for towing... if done right. Unfortunately, most tuners are there to feed the coal burners's itch and to make a fast buck... rather than pamper the transmission and crankshaft. Some hard-core homework will yield suggestions on this one, but for the love of Gawd - don't open a thread titled "Who's the best tuner?". Use that line as a search string, grab a beverage, and wait for the search results to max out the RAM in your computer.

 

Seeing as we are jumping into the deep end...

As others mention, first is to make sure the truck is tight. Meaning no leaks in the intake or exhaust plumbing. Another aspect is to harden the transmission.

As this is looking like a travel trailer deal, before going out on any journey consider taking the rig to a CAT scale to make sure the hitch is set up correctly. There are plenty of discussions on proper weight across all the axles. A crude measurement is the eyeball test where the truck and trailer should look relatively parallel to the ground (on a flat surface anyway). If the truck is squatting or the trailer is nose high / low, not so fun things can happen.

Will break a bit from Mark's awesome advice with a nuance and admission that I have not towed a 7.3 with an automatic, but have with other automatics. If you are using cruise control, watch speed when climbing hills. Sure the transmission will kick-down as Mark mentions, and at the same time I do not like losing a mile per hour or three before the truck does this as it means the system will work even harder to get back up to the set speed. To avoid any noticeable speed loss I manually kick the transmission down when I know that the hill will cause a downshift. Over time you will learn how the truck behaves and know when to predicatively downshift (if at all).

Given that the truck is completely stock (except for the trans cooler), might want to swap out the air filter housing for something that breathes a lot better. This is easy enough to DIY and no other supporting mods are necessary.

 

I have been for 13 years. My tunes and my Valve body do modify my shift points, and even the revision of your factory ECU flash will afffect your shift and Torque converter engagement points.

If I'm in hills I disengage cruise control and preemptively disengage OD to keep the r's above 2k. If I do not, the cruise will add to much fuel at too low RPM and cause black smoke, which I hate.
A more modern tune would likely lessen this, mine is over 10 years old.

 

Thank you for the replies. Keep them coming. I will take all the advice I can get. I called and looked around locally for a pyrometer guage or two but could not locate one. I will have to order something. So this first trip out with the trailer will be with just stock gauges.

I am trying to decide on all analog guages. Or a edge insight, or a mix of both. What are your opinions?

Also if I was to go in and do a 4" turbo back exhaust and replace the up pipes. What else should I do while I have acess back there?

And just FYI, the pass I will be going over is 3k feet elevation and up to a 5% grade.

 

The valve body can't affect when the trans shifts, it can only affect how firm or soft it shifts. When it shifts is 100% from the tunes.