Thread: D2 towing and fuel advice AdrianS

The important thing to do with towing a heavy trailer/caravan is to ensure that the transmission torque converter is locked as much as possible. You can tell it is locked if you put your foot down and the revs do not rise more than the speed rises.

The TC locks at 80Kmh in D and stays locked down to 70. In 3 it locks at 70Kmh and stays locked down to 50Kmh. ( in my TD5 anyway.)

So its up to you. If you can maintain a little more than 80kmh with the TC locked then it's OK. When you come to a hill an early change down to 3 will ensure that the trans locks into 3. The technique I use is to wait for the upchange to 3 if accelerating , take it gently to 70Kmh , wait for lockup then accelerate harder. when the car reaches 80 plus I change to D then ease off until I see the tacho drop then accelerate normally.
Others with temp gauges on their trans point out a large difference in temperature when the TC is locked vs unlocked.

I also use full synthetic Castrol Transmax Z which is promoted as reducing Trans temperature by 20C and is fully approved by ZF for 4HP22E.

Some heavy towers also fit an additional cooler.

Personally I don't like using Sports mode as I don't think it locks up as much.
However I do not tow over 1 tonne.
Regards Philip A

Originally Posted by PhilipA

The important thing to do with towing a heavy trailer/caravan is to ensure that the transmission torque converter is locked as much as possible. You can tell it is locked if you put your foot down and the revs do not rise more than the speed rises.

The TC locks at 80Kmh in D and stays locked down to 70. In 3 it locks at 70Kmh and stays locked down to 50Kmh. ( in my TD5 anyway.)

So its up to you. If you can maintain a little more than 80kmh with the TC locked then it's OK. When you come to a hill an early change down to 3 will ensure that the trans locks into 3. The technique I use is to wait for the upchange to 3 if accelerating , take it gently to 70Kmh , wait for lockup then accelerate harder. when the car reaches 80 plus I change to D then ease off until I see the tacho drop then accelerate normally.
Others with temp gauges on their trans point out a large difference in temperature when the TC is locked vs unlocked.

I also use full synthetic Castrol Transmax Z which is promoted as reducing Trans temperature by 20C and is fully approved by ZF for 4HP22E.

Some heavy towers also fit an additional cooler.

Personally I don't like using Sports mode as I don't think it locks up as much.
However I do not tow over 1 tonne.
Regards Philip A

Thanks for that PhilipA I wasn't aware of that it makes some sense, I did a full fluids change (engine, trans, brakes, diffs and trasfer box) using the fluids recomended for the vehicle in the manual before we left Perth. The incline I mentioned is a continuous low barely perceptible gradient for several hundred km's comming into Halls Creek with occasional flat sections and steeper gradients, on the flats I was driving at 85 - 95kmh and when on the incline I tried to maintain a steady 80kmh in drive but the climb generally wasn't so steep that it kicked back into 3rd. However when we encountered the steeper sections and the tranny kicked down to 3rd is when the tranny overheated so we immediately stopped when it was safe to do so and let the tranny cool down. The red tranny overheated light turned off almost immediately as we stopped and if we were pulled over in a safe area we waited for 15 - 30 min then continued, if stopped on the road verge in a dangerous position continued after the light extinguished till we could pull over safely and wated to cool down. So should I have tackled this entire inclined section in 3rd or drive?
I find it strange that a vehicle with such a large engine should find towing a load at half it's rated capability such a task and use up so much fuel in doing it. Anything else I should be looking at or doing diferently that comes to mind? Is this fuel economy reasonable or expected?
Thanks AdrianS

Originally Posted by applesauce

I did a full fluids change (engine, trans, brakes, diffs and trasfer box) using the fluids recomended for the vehicle in the manual before we left Perth. T

Trouble with the auto is that you really only change half the fluid doing it in the normal way. Not saying that this was the cause, but it's worth bearing in mind.

I've been considering getting someone to weld 'wings' onto the sump on mine. More oil the better, I reckon.

phillipA is on the right track

When i tow cars etc with my td5 the most important thing i find is to drive to keep it with the converter locked up and have had no issue with it at 110/115km/h on the freeway's in drive out of sports mode.
however if i see a hill that i know i cant hold 4th locked up ill down shift to 3rd before the bottom of the hill let the converter lock up then pull up the hill in 3rd.
basically you gotta drive it to keep the converter locked up doing so will keep the temp's down
so that may mean to drive in 4th you have to drive at around 100 if you dont want to go that fast you might have to use 3rd but only do 75 to keep the revs down, but at the end of the day you cant just set and forget you have to drive it and anticipate what your going to need.
if the temp overheat light comes on immediately pull over and let it cool off as the warning light sender is back a fair way where the oil is cooler.

if your going to do a lot of towing then fit an extra cooler for the trans

what speed have you mainly be traveling at?
if you have been doing 80-90km/h with the van you have probably had too much load for the converter to want to lock up.

as for fuel i would expect it to be using somewhere between 15L to 20L if its not windy, if you have been getting head winds expect 30L+

sports mode in the td5 i find to just be worse as it hangs onto gears longer and gets it off the torque band too much and well it dont have horsepower lol

Originally Posted by lyonsy

phillipA is on the right track

When i tow cars etc with my td5 the most important thing i find is to drive to keep it with the converter locked up and have had no issue with it at 110/115km/h on the freeway's in drive out of sports mode.
however if i see a hill that i know i cant hold 4th locked up ill down shift to 3rd before the bottom of the hill let the converter lock up then pull up the hill in 3rd.
basically you gotta drive it to keep the converter locked up doing so will keep the temp's down
so that may mean to drive in 4th you have to drive at around 100 if you dont want to go that fast you might have to use 3rd but only do 75 to keep the revs down, but at the end of the day you cant just set and forget you have to drive it and anticipate what your going to need.
if the temp overheat light comes on immediately pull over and let it cool off as the warning light sender is back a fair way where the oil is cooler.

if your going to do a lot of towing then fit an extra cooler for the trans

what speed have you mainly be traveling at?
if you have been doing 80-90km/h with the van you have probably had too much load for the converter to want to lock up.

as for fuel i would expect it to be using somewhere between 15L to 20L if its not windy, if you have been getting head winds expect 30L+

sports mode in the td5 i find to just be worse as it hangs onto gears longer and gets it off the torque band too much and well it dont have horsepower lol

Thanks lyonsy I've been traveling at 80 - 95kmh with no headwinds the reason being this van tends to be susceptable to swaying above this range and the roads up here ain't the best which dosn't help at all. Also it's an old van with a rated ATM of 2000kg but its sitting at arround 1800kg at present as well as it's not as aerodynamic as newer ones and may be getting some wind resistance but I'll try to keep to 95 on the flats and see how that fares. I haven't been aware of the tc lockup so I'll pay attention to it from now on I'm assuming this will aid my fuel consumption as well and I'll be traveling in 3rd and 75kmh on steeper inclines from now on. But as I said the road from Dreby to Fitzroy crossing and onto Halls Creek here has a barely perceptible gradient but it's consistant pretty much the whole way what should I have done these sections in 3rd and 75kmh or sped up to try and get TC lock? Thanks AdrianS

Originally Posted by johntins

Trouble with the auto is that you really only change half the fluid doing it in the normal way. Not saying that this was the cause, but it's worth bearing in mind.

I've been considering getting someone to weld 'wings' onto the sump on mine. More oil the better, I reckon.

Hi johntins what do you mean by "wings"

Thanks lyonsy I've been traveling at 80 - 95kmh with no headwinds the reason being this van tends to be susceptable to swaying above this range and the roads up here ain't the best which dosn't help at all. Also it's an old van with a rated ATM of 2000kg but its sitting at arround 1800kg at present as well as it's not as aerodynamic as newer ones and may be getting some wind resistance but I'll try to keep to 95 on the flats and see how that fares. I haven't been aware of the tc lockup so I'll pay attention to it from now on I'm assuming this will aid my fuel consumption as well and I'll be traveling in 3rd and 75kmh on steeper inclines from now on. But as I said the road from Dreby to Fitzroy crossing and onto Halls Creek here has a barely perceptible gradient but it's consistant pretty much the whole way what should I have done these sections in 3rd and 75kmh or sped up to try and get TC lock? Thanks AdrianS

Thanks for that PhilipA I wasn't aware of that it makes some sense, I did a full fluids change (engine, trans, brakes, diffs and trasfer box) using the fluids recomended for the vehicle in the manual before we left Perth. The incline I mentioned is a continuous low barely perceptible gradient for several hundred km's comming into Halls Creek with occasional flat sections and steeper gradients, on the flats I was driving at 85 - 95kmh and when on the incline I tried to maintain a steady 80kmh in drive but the climb generally wasn't so steep that it kicked back into 3rd. However when we encountered the steeper sections and the tranny kicked down to 3rd is when the tranny overheated so we immediately stopped when it was safe to do so and let the tranny cool down. The red tranny overheated light turned off almost immediately as we stopped and if we were pulled over in a safe area we waited for 15 - 30 min then continued, if stopped on the road verge in a dangerous position continued after the light extinguished till we could pull over safely and wated to cool down. So should I have tackled this entire inclined section in 3rd or drive?
I find it strange that a vehicle with such a large engine should find towing a load at half it's rated capability such a task and use up so much fuel in doing it. Anything else I should be looking at or doing diferently that comes to mind? Is this fuel economy reasonable or expected?
Thanks AdrianS

Hey Adrain when it comes to hills its not so much about keeping to a set speed but holding onto the converter how i do it is i select it at my current road speed revs will jump a lot then it will drop around 200-300 this is the converter locking up,
I then give it too it till i start to gain some speed and then hold those revs if its real step and the engine starts to labour down in the revs ill slowly back the throttle so the trans doesent come out of lock up if you do this you should be able to keep the converter locked up down to around 70km/h once ya start getting below that it will become more difficult and 2nd wont lock up for you (it can but rarely)

wings are basically a metal box out the side of the sump to increase the oil capacity

and yeah at 80km/h you would of been out of lock up and even when you where doing 85-95 on a slight grade there is a good chance you dident have it lock up ether, thats what has happened is you have been driving for long periods of time with the converter unlocked which when its like that it relies on the fluid to transfer drive (basicly think of 2 fans you turn one of and face the other one at it off the one that is on will drive the one that is off) which even at its best has a 7% loss rate but also generates a lot of heat,
the heat has then broken the oil down which then allows damage to happen and becomes a viscous cycle until something breaks

so because you have been out of converter lock up you would of also been using more fuel as well

also with the oil if your able to change it your self just get the cheapest dex3 oil you can find as all dex3 comes from the same plant for australia (or did this was a couple of years ago) and just change the oil every service if your doing a lot of towing or every 2nd service as its prob the easiest auto to change the oil on i have come across.

as for the repair shop saying drive it in 3rd thats a safe way to tell someone how to keep their auto alive with out having to go into the detail i and phillip have gone into as its the select and forget mode

Originally Posted by applesauce

Hi johntins what do you mean by "wings"

Sorry. What lyonsy said. Haven't looked yet to see if there is room. I have never felt that the 4HP22 holds enough oil. A bigger cooler is one answer, a bigger sump is another. I wouldn't want my sump to be any lower, so 'wings' might be an answer.