Towing an Escape 21: 4Runner or Tacoma?

[Brian B-P]

Originally Posted by soultrek

I am towing a 17B with a 98 4runner. The V6 produces horsepower and torque under 200. It has no apparent transmission cooler or transmission temp gauge.

It's normal to not have a transmission temperature gauge in a car or light truck. On the other hand, there normally is a cooler for the automatic transmission, but it can be hard to identify, because it is normally built into the radiator... the only evidence is a pair of small hoses connecting the transmission to the cold-side tank of the radiator.

Originally Posted by soultrek

The owner's manual recommends towing uphill in Drive; cautions against doing it in 2nd or 1st. On steeper grades, to avoid continuous automatic shifting back and forth between 3rd and 2nd, I manually go to 2nd.

The frequent shifting is usually called "hunting", and manually selecting the lower of the two gears is the normal way to address this.

Originally Posted by soultrek

This produces a steady climb at 40mph and mid-range RPM, with no apparent change in engine temp and never any warning lights.

Sounds very reasonable to me, assuming that 40 mph is adequate for traffic and road conditions.

Unfortunately, a hot transmission will not likely be seen as an increased engine temperature; however, it is at least likely that the transmission fluid is going through a cooler in the engine's radiator, and getting good cooling since the engine coolant is at the right temperature.

Originally Posted by soultrek

My transmission fluid looks good. My question: is this possibly doing harm that is not otherwise apparent, and would I really be better off letting it continuously shift back and forth in Drive?

I can't believe that allowing excessive shifting would be a good idea. If it were mine, I would continue to use 2nd as required in this situation.

[gbaglo]

Now that I'm an old fart I don't really give a what people think.
I've heard RAV4 described as being for soccer moms.
Not sure where you would put the balls.

[Brian B-P]

Originally Posted by gbaglo

It says to tow in 4, not in Drive ( which I believe is overdrive ).

If the only thing higher on the selector than "4" is "D", then "D" is 5th... it really doesn't matter if it is an overdrive ratio or not. Modern transmissions can have one, two, or even three overdrive ratios.

[gbaglo]

Whatever. I'm just following the instructions in the manual. Don't want to see the transmission warning light again.

[floorpanel]

I have driven 3/4 tons and 1 tons for years and used to sneer at the 1/2 tons so I can take any remarks that come my way. I just laugh when I don't have to back up twice to get in a parking space and have no problem getting in the garage.

[paulw]

Originally Posted by TAfraser

Paul, I may not make the spring NOG in April. My daughter is due with her first on April 25. Very rude of her isn't it?
Tom

Can't think of a better reason to cancel a trip then to be there for your daughter - I know I did. + grand kids are cool! Ours is coming to spend the day tomorrow.
If you do end up canceling, try and coordinate with Donna D.... I think she knows of a few folks who are looking for a spot.

[TAfraser]

floorpanel, one of the guys who made fun of the Ridgeline also called my Casita a tow-able port-a-potty. He of course drove a 3/4 ton diesel towing a 32' 2 slide-out trailer. I get no respect!!

[dave macrae]

Thats ok ...you get the last laugh, we all know that 32fter with slides is leaking somewhere

[paulw]

I wonder how often he makes a trip like this:

"We’re going from Washington State, to San Francisco, up the coast to the Redwoods, inland to the Bend area, back out to the coast to the Tillamook area, up to Mt. Rainier, and over to Sequim."

with his big rig .

[floorpanel]

I have had a 32ft Airstream and a 28ft stickbuilt and I wouldn't trade either one for a fiberglass trailer. I have never enjoyed working on a vehicle or a trailer.

[floorpanel]

I think I said that wrong, I would not trade a fiberglass trailer for either one.

[Rossue]

Hi Jerry....are you sure? Maybe you should let me scratch my 2'-itis twice and lemme take your 21(-;

[TAfraser]

You guys make me laugh, TANKS.

By the way, that guy with the 32fter; probably does have a leak because when he's on the flats, and his wife is asleep, he'll travel at 90mph. I think he has way too much "T".

[Gr8Escape]

A late reply, sorry Brian! I was out of the forum for a while.....
In the Tacoma I tried to have the rpm in the range of maximum torque band on the 4l V6, that is between 3000 and 4500 rpm. Once below 3000 rpm the torque rapidly drops of for the most part.
In the Jeep GC with MB diesel 3 l V6 with the MB auto tranny the rpms were much lower, as I recall between 2000 and 3000 rpm. The max torque is available at a low 1800 rpm. I would have set cruise at 95 or 100 kph, the auto transmission did an excellent job of just in time downshifting and staying in the ideal torque band, but even going up the steepest section of the Coquahalla it would shift down at the most 2 gears. The same trip without trailer it would drop just one gear.
In my experience the 2006 Jeep Liberty with a 4 cylinder 2.8L diesel was a great tow vhicle with the 17 ft Escape - albeit less capable, but more noisy and less comfy than the Grand Cherokee.

[Brian B-P]

Originally Posted by Gr8Escape

I have been towing a 19' with a 2012 Tacoma with 6 speed manual transmissionfor the last 2 years. I find that the combination is very stable, but I find power and torque to be disappointing. It is fine on the flat lands but for hills and inclines I find it is not able to maintain speed with the traffic flow, in fact I find that myself having to tuck in behind the 18 wheelers for anything over 5% climbs.

Originally Posted by Brian B-P

What engine speed do you use in the Tacoma to climb hills, when you need as much power as you can get to keep up? What engine speed did the Grand Cherokee run (I'm guessing it's an automatic left in Drive)? I'm curious about whether or not the potential of these engines is used.

Originally Posted by Gr8Escape

A late reply, sorry Brian! I was out of the forum for a while.....
In the Tacoma I tried to have the rpm in the range of maximum torque band on the 4l V6, that is between 3000 and 4500 rpm. Once below 3000 rpm the torque rapidly drops of for the most part.
In the Jeep GC with MB diesel 3 l V6 with the MB auto tranny the rpms were much lower, as I recall between 2000 and 3000 rpm. The max torque is available at a low 1800 rpm.

Thanks for the reply

I don't have the full power/torque curves of the Tacoma engine available, but we do know that at full throttle and 4000 rpm it is putting out (at sea level) 202 hp. 4500 will be something under 227 hp. At only 3000 rpm, it will be producing significantly less torque, at lower speed, for something much less than 150 hp. This is a reasonable speed range in which to run the engine continuously, and it's probably quite efficient in that range, but at the lower end it is putting out less than half its peak power. If you're willing to keep it at the top of that range - or higher - there is a lot more power available.

This is certainly not a case of "screaming a engine at high rpm to get that last bit of power", since it is running at one-half to two-thirds of peak power output, at speeds well below that required to produce peak power, let alone the engine's operating limit.

The broader torque curve of the Grand Cherokee's engine is due to the turbocharger. Even it must rev faster to get more power, but in general it is using more torque at lower speeds to get the same required power.

[Gr8Escape]

I found a description somewhere on the web : ............Here's a better representation of Toyota's 4.0L torque curve : Below 3000 rpm, there's not much there. From 3000 to 5500 rpm, it's stout......[end quote]
Unfortunately I did not manage to copy the graph, however it confirmed what I stated previously: the torque curve plunges almost straight down below 3000. From 3000 to 5500 it produces from 200 to 275 ft lbs.
As is the case with most gasoline naturally aspirated engines the increase in horsepower is pretty much close to linear with the increase in rpm. By the same token turbocharged and supercharged engines provide much more torque at lower rpm. This holds true for both gasoline as well as diesel engines.
Due to the higher rpm required for the Toyota 4l V6 to produce sufficient torque AND horsepower, it will burn significantly more fuel and I would imagine it would wear faster than the diesel running at a more leisurely rpm range.

[Brian B-P]

Originally Posted by Gr8Escape

I found a description somewhere on the web : ............Here's a better representation of Toyota's 4.0L torque curve : Below 3000 rpm, there's not much there. From 3000 to 5500 rpm, it's stout......[end quote]
Unfortunately I did not manage to copy the graph, however it confirmed what I stated previously: the torque curve plunges almost straight down below 3000. From 3000 to 5500 it produces from 200 to 275 ft lbs.

Good info. I can refine my earlier comment:

Originally Posted by Brian B-P

At only 3000 rpm, it will be producing significantly less torque, at lower speed, for something much less than 150 hp.

200 lb-ft at 3000 rpm is only 114 horsepower.

This part remains even more valid:

Originally Posted by Brian B-P

If you're willing to keep it at the top of that range <of 3000 to 4500 rpm> - or higher - there is a lot more power available.

[Mike Lewis]

Regarding RAV4 vs. Tacoma's towing capacity: could a longer wheelbase play a part in the Tacoma's higher rating (assuming the Tacoma is longer than a RAV4)? I know that the Wrangler-type Jeeps are usually rated with a low towing capacity even though sometimes they have the same engines as larger Jeep models. I've always assumed that was because their short wheelbase made them less stable when towing.

If this has already been mentioned, well, I just skimmed this thread; sorry.

Mike L.

[Mike Lewis]

I meant 4Runner, not RAV4. Dang.

[Brian B-P]

Originally Posted by Mike Lewis

... could a longer wheelbase play a part in the Tacoma's higher rating (assuming the Tacoma is longer than a [4Runner])? I know that the Wrangler-type Jeeps are usually rated with a low towing capacity even though sometimes they have the same engines as larger Jeep models. I've always assumed that was because their short wheelbase made them less stable when towing.

The wheelbase is a factor in stability and occasionally drives a difference in ratings - the Wranglers are an excellent (and rare) example. I don't think any pickup truck is short enough for this to be a factor (they are usually just drivetrain, rear suspension, and frame limited). The shortest Tacoma is shorter in wheelbase than the longest Wrangler (which is not a short vehicle at all), although most are somewhat longer; any Tacoma has a longer wheelbase than the shorter Wrangler (a couple feet longer in most cases). The shortest (2WD regular cab) current Tacoma has the same wheelbase as a 4Runner, but most are significantly longer.

Although limiting tow rating due to wheelbase is rare, my guess is that we might see more of it as the SAE J2807 rating standard is used, since it includes a stability testing component. Just a guess...