Towing 4th Gear

For the guys that tow a lot!

My prerunner has the 4.0, factory tow package with tranny cooler.

I was towing my boat today and normally use 4th gear at 65mph @ 2750rpms.

Today I bumped it up to 70mph @ 3000rpms. Towing the boat to the lake is generally a 45 min drive.

My question: If I do run 70mph @ 3000rpm, will this increase the transmission fluid temp? I do not have a way to monitor the fluid temps. Was hoping someone who monitors theirs while towing will chime in. Thanks!

Outside temps typically 85-95.

 

Not by enough to worry about. It will be miniscule if any.
You'd be better off in 4th at 70, than in 5th and having the convertor constantly lock/unlock.

Yes. I do, and have, ran 70 mph in 4th for extended periods.
Transmissions are expensive, engine oil is cheap.

 

probably run cooler just with extra airflow. In 4th with the torque converter locked up heat wont be an issue. You are fine.

If you were worried about trans temps, move the stock cooler up ~ 2-3 in so its not behind the grill and up in the airflow. Once I did that, I havent worried about trans fluid temps after seeing temps stay very much inline not to hot even in 100+ deg ambient loaded up big time going up big grades in 3rd gear at 4k rpms.

 

These are the simple kind of fix/mediation that I LOVE

 

Does the boat really need to get towed at 70+ mph in 90ºF heat?

How about 55 mph. It'll add easily +4 to 5 mpg fuel economy as well.

 

You are In California where towing a trailer speed limit is 55 mph. Most other states don’t restrict speed to 55. You go what ever the speed limit is. while towing.If it’s 70 you go 70. If you are towing at 55 mph in a state without the 55 restriction people are going to be up your ass. And you’ll hear honking horns all day long.

 

That’s what I was thinking. Go 55 in an 85 in Montana... That said I dont push my bearings beyond 75.

 

Ok, then 60. Even 60 is going to save lot of gas vs. 70-75mph when towing.

If it's a 1-lane-per-direction road, sure, you need to keep pace and not hold up a line of cars behind you. If it's 2 or more lanes each direction, people can do this sophisticated high-skill action called "passing on the left".

In Montana or other special-case autobahn-enabled states, all bets are off & I agree it's not safe drive more than 10 mph below the prevailing speed of traffic. Burn that gas and heat up that tranny but-good.

 

You've never owned a boat before I see?

There are 2 things you can never do if you own a boat.

You can NEVER get to the lake fast enough.
And you NEVER get home fast enough.

I no longer own a boat. I owned one, ONCE.........

 

Well. I own an inflatable kayak. It weighs about 25 lbs. I tried towing it once but it just flapped in the wind like a Dixie flag on a stick in the back of a beater 1983 Chevy pickup.

Tried to find a "Dixie flag" animated gif on Giphy but nope, shadow-banned. Whatever, I'm from california anyway and haven't ever visited a state below the Mason-Dixon line.

 

In my opinion, you’re better off with the inflatable kayak.
Boats are for people who have extra money to throw away.
I’m not one of those people.

 

Yea, boats -- at least any real boat, anything longer than ~15-17 feet and more than 1000 lbs or so -- are like horses, for the rich only.

I just got the inflatable, seems like its decent quality. If this is my last post ever to TW forums a good guess will be that it spontaneously deflated out on some lake and I didn't make it back.

I kid -- I'm not going out there without a good PFD, AND a wetsuit if the water is cold, and a good set of swimming fins to make it back to shore if needed.

 

The answer to your question is in a monitor

which you should have

 

Guess you haven't been to Texas lol, if you aren't going at least 5 over the speed limit (60-70 on most 2 lane roads) your gona have someone so close to your rear they may as well give you a push. If your near one of the bigger cities on a main highway you better be going 80-90 or get off the road.

 

Chill man. What are you racing for. Take care of your equipment.

 

I'm also in the no-need-to-rush camp. Air resistance/drag increases by the square of the velocity. We drive cinderblocks on wheels to begin with, before hitching anything to be back. My MPG tanks at anything over 60-65. So increasing speed from 65 to 70+ while towing more weight and lots more drag, will only be burning heaps more fuel and putting lots more stress on your drivetrain, just to get to your destination marginally/unnoticeably sooner by a couple of minutes.

Chillax. Take it easy and just enjoy the trip. Towing in general can be exhausting, much more so when pushing your machine to its limits and worrying about grenading a transmission on the way. Other drivers can pass you on the highway. Even 2-lane roads will have passing zones. People rushing while towing is when stupid accidents and/or breakdowns happen.

Take the money you'll save on gas and trans rebuilds, and buy a good set of dash/trailer cams instead.

 

Running more RPM's keeps everything running cooler. That's why you run in 4th gear. In overdrive and lower rpm's your engine is actually working a lot harder, using more fuel and running hotter when towing. In fact in hilly or mountainous terrain its a good idea to run in 4th even when not towing.

 

This is spot on^^^^^^^. Sometimes on steep mountain roads while towing my boat I’ll even run in 3.
I don’t know why some got all hung up on mpg. The OP wasn’t asking about that, only asking about rpm’s and temps. I’m sure he’s aware the faster you go in general the more fuel you burn.

 

I don’t disagree with what y’all are saying. In general, yes, higher rpm is better for cooling than lower for a given load.

But in this case higher rpm means higher speed, which (at this speed) means considerably and disproportionately higher drag for each mph gained. Overcoming this drag means producing more power (by burning more fuel) and generating more heat/strain throughout the power train. So even with a bit of extra airflow/rpm, you’re basically back to square one at best for cooling, but with all the added drag it’s now pulling against as a function of the speed.

Its a balance. Sure, you can put the hammer down in lower gear, and the truck will do it. I’ve done it. But it’s important know that you’re adding all that extra strain (drag plus towed weight) to every gear, clutch, bearing, and u-joint in the drivetrain to save a few minutes.

Orrr you could just accept 60-65mph as a good enough speed, be okay with it being a 48-minute trip vs. 45, get significantly better MPG, and save all the stress of trying not to deep-fry your trans.

To each their own, I’m just some guy on the internet with an opinion lol.

 

I'm not saying 70 is better than 65, when towing I rarely get over 65, never over 70. Just that a consistent 3000 rpm isn't going to hurt anything with these trucks.

Sometimes you have to decide if getting home a little sooner is worth the extra fuel. For a short 45 minute drive probably not. But I've done a few cross country trips driving as much as 950 miles solo and 1700 miles non-stop swapping out drivers to get home. Driving 75 vs 70 got me home 2-3 hours sooner. It probably cost me 5-10 gallons more in fuel. But I made the decision that it was worth it to me.

Another thing to remember is that these trucks need 3600 rpm to get max torque. 3rd gens need 4600 rpm's, they are designed to run fast.