Caravan Towing 150 Series

[smithie Lurker Find all posts View Profile Close smithie]

I tow a 2 tonne caravan with 2012 Prado 150 Diesel auto. The manual recommends towing in Sports Mode 4th gear to optimise electrical generation and brake assist. I have spoken with some 150 Series people who tow in D, which reduces engine revs and improves fuel efficiency. Does anyone know if this approach would affect the engine and/or transmission

[RanJ Avid PP Poster! Find all posts View Profile Close RanJ]

For me (don't own a 150) I keep mine out of overdrive everywhere but the highway and the first sign of an incline... back out of overdrive. I do it for fuel efficiency

[D4D Addicted PP Member Find all posts View Profile Close D4D]

If you want to keep your auto trans healthy then drop it out of top gear when towing that sort of weight.

[A10 Member Find all posts View Profile Close A10]

First of all, get a Scangauge or similar so you can measure transmission temperature. You will soon work out the correct gear to use.

I mostly use S4 although on freeways with long downhill or flat sections, I might put it into D at times. Any sign of a hill and put it back into S4.

[wooley Avid PP Poster! Find all posts View Profile Close wooley]

S4... towing even an empty trailer in D will burn out your trans quicker than you would think

[yowie Advanced Member Find all posts View Profile Close yowie]

Smithie,

The manual recommends towing in S4, and that's what I do with a similar weight van with a petrol 150. I only use S5 on a long gentle downwards slope. Preferable to keep engine revs around 2,000 or a bit higher.

As Wooley stated, using D, or continual S5, will cook the trans eventually.

S5 is an overdrive gear, and while it may save you some fuel costs, the long term costs may not be worth the fuel saving.

[krypto Avid PP Poster! Find all posts View Profile Close krypto]

The problem with running in D is that as soon as there is any load on the transmission the lock-up drops out (you'll see a small rise in revs) and you are running on the torque converter. The torque converter is really just a fluid coupling, this generates a lot of additional heat in a gearbox that already runs pretty hot. (Google it if you want to see what a torque converter does). I also suspect that 5th gear or overdrive is not designed to handle the torque generated when towing a load

End result is that you run the oil at and above its limits resulting in additional wear on the transmission. I've done a lot of testing moving between D and S4 when towing and there is marginal difference in fuel consumption, I just don't like the sound of the engine revving. I do the same as A10, which is use D on flat stretches where there is not much load on the transmission.

[Gav&Jo Lurker Find all posts View Profile Close Gav&Jo]

Hi Smithie. We tow a 2000kg Coromal full sized van with our Auto Turbo Diesel 150 Prado. The issue re which gear to tow in has always baffled me. I note that if I tow in D, then unless the road is flat, or we have a tail wind, the gearbox does a fair amount of hunting, or wants to sit in that talk converter rpm between 4th and 5th. So, I use sports shift S4 unless the road is flat, or I can sit in the 100kph to 110 kph range. It's happy to sit in 5th at, or over 100kms, but unless I can maintain such speed, then it doesn't take much of a hill, or traffic to make it want to pop back to 4th anyways. What I must say is that unlike others who happily report fuel figures of 12ltr/100km towing 2500kg vans..... I can't get anywhere near such economy. Our Prado is averaging between 16-17ltrs/100kms towing with a mixture of S4 and S5, depending on conditions, speed, wind etc. (I don't know why, but adding 45mm lift, LT tyres and maintain 100kms/hr where possible net a 2-3 ltr/100km fuel gain when towing...go figure?!). If it's tough going with lots of S4 work, then the car is up around the 18 - 19ltrs/100kms at 95-100kms/hr- it's reving quit high, hence the fuel usage I guess. And if we are pushing big headwinds, then I've seen 20lts plus/100kms figures at just 90-95kph! I sure chipping and larger exhausts may be the way to go for towing big vans, but I'm not sure if more power would fix the issue with towing in D or S5.....not that I've got the courage to add such modifications just yet!

[Bushbasher Out of control poster! Find all posts View Profile Close Bushbasher]

What I must say is that unlike others who happily report fuel figures of 12ltr/100km towing 2500kg vans..... I can't get anywhere near such economy.

Oh yeah, sure. In their dreams.

[krypto Avid PP Poster! Find all posts View Profile Close krypto]

I regularly tow a loaded up Prado with stuff on the roof and a big coromal camper that with water etc probably pushes +1600kg and get 13-14l/100km. Tyre pressure and speed over 100km/h have a huge impact on fuel use.

[gspy4u Senior Member Find all posts View Profile Close gspy4u]

just short of 2.5t tandem axle caravan, full tank of fuel with family and gear in ours and average 15's, worst was 17ltrs against a head wind up and down hills. And sit on the speed limit whatever it may be, as well as overtaking cars and such when needed.

[The Alberto Member Find all posts View Profile Close The Alberto]

Hi Smithie. We tow a 2000kg Coromal full sized van with our Auto Turbo Diesel 150 Prado. The issue re which gear to tow in has always baffled me. I note that if I tow in D, then unless the road is flat, or we have a tail wind, the gearbox does a fair amount of hunting, or wants to sit in that talk converter rpm between 4th and 5th. So, I use sports shift S4 unless the road is flat, or I can sit in the 100kph to 110 kph range. It's happy to sit in 5th at, or over 100kms, but unless I can maintain such speed, then it doesn't take much of a hill, or traffic to make it want to pop back to 4th anyways. What I must say is that unlike others who happily report fuel figures of 12ltr/100km towing 2500kg vans..... I can't get anywhere near such economy. Our Prado is averaging between 16-17ltrs/100kms towing with a mixture of S4 and S5, depending on conditions, speed, wind etc.

I tow a 2.2 tonne Full van (not poptop). I am with Gav, never seen fuel useage under 17 and generally up around 18. Prado and van tyres all on 40psi. I tow in S4 for the most part, but drop into D for flatter roads and I sit on 98kph according to the Sat Nav. I have no idea if this is right or wrong, just what I do. I know plenty of old timers that tow regularly and they are in Prados with 2T + on the back who always tow in D with no problems. They justify it by saying "the gearbox knows better than me what gear it needs, when it loads up it changes down etc".

Interesting issue and also the number of different opinions on the subject, especially given the manual recommends towing in "S".

We are heading to Cairns in 2 weeks with the van on so I've got 2200k+ of towing in front of me. Hopefully I am doing it right

[krypto Avid PP Poster! Find all posts View Profile Close krypto]

I tow a 2.2 tonne Full van (not poptop). I am with Gav, never seen fuel useage under 17 and generally up around 18. Prado and van tyres all on 40psi.

I strongly suggest that you check your tyre temps/pressure on the road. I bought a cheap thermal scanner from Supercheap to check both the tyres and my transmission temps, which is why I fitted an oil cooler. You will find that the tyres are running quite hot and getting up around 60psi (hot). After a lot of experimenting I run the back tyres on the Prado at around 50-52 (cold) when towing and this gives me a rise to 56-58 when hot.

I also run the camper tyres at 50-52 (cold) and they get an even bigger rise in temperature/pressure. This is understandable when you work out the load on the tyres.

My mate runs the same pressures with the same results. Bottom line 40psi when towing, particularly open road and hot weather is way to low. You'll get extra tyre wear, greater fuel consumption and a greater chance of tyre failure.

[Bassett Member Find all posts View Profile Close Bassett]

I have a 3 door SX and tow a 2500kg caravan and run the tyres (BFG A/T’s) on the Prado at 40psi front and rear. I have a TPMS fitted and it shows that pressures generally only increase about 4 or 5 psi and the temp has only got up between 50 and 60 degrees C on a couple of occasions on hotter days on undulating western Qld roads. I run the van tyres at 50psi.
Fuel consumption when towing is around the 17ltrs per 100klms traveling at between 90 and 95kph. This has been my experience over the last 3 months of towing the van for about 3000klms.

[The Alberto Member Find all posts View Profile Close The Alberto]

I strongly suggest that you check your tyre temps/pressure on the road. I bought a cheap thermal scanner from Supercheap to check both the tyres and my transmission temps, which is why I fitted an oil cooler. You will find that the tyres are running quite hot and getting up around 60psi (hot). After a lot of experimenting I run the back tyres on the Prado at around 50-52 (cold) when towing and this gives me a rise to 56-58 when hot.

I also run the camper tyres at 50-52 (cold) and they get an even bigger rise in temperature/pressure. This is understandable when you work out the load on the tyres.

My mate runs the same pressures with the same results. Bottom line 40psi when towing, particularly open road and hot weather is way to low. You'll get extra tyre wear, greater fuel consumption and a greater chance of tyre failure.

Thanks for the advice Krypto. I will have another look at everything before we head off - I got a real flash new tyre pressure gague for Father's day so any excuse to whip it out! I must admit though, I have never even thought of running the tyre pressures that high. I will go up to 50 on the van and I think I will start the car at 40 (cold). I am planning a stop at about 100k up the road for coffee so I will check all the tyre pressures then once they are hot. I will apply the 4psi rule and see how far out I am and maybe adjust the pressures then.