Vehicle ratings

same happened with the 80 series, 1995 could tow 2500kg, 1996-7 were able to tow 3500, and the landrover discovery started it all with a 3500 rating.
I dont know the answer to the question, other to say vehicles entering Australia are pre tested and a blanket rating given to all that model varient. Personally i see alot more utes with 3500 rating come to grief than cruisers and patrols with thesame rating. It usually occurs with adverse whether, especially wind, but rain too.
I put it down to the tail wagging the dog.

"same happened with the 80 series, 1995 could tow 2500kg, 1996-7 were able to tow 3500,"

The towing up-rating followed an upgrade of the front brakes.

However in relation to the Discovery 4, the towing weight or speed reduces when doing dirt road and $wd tracks. I cannot remember which and my car is with a friend so I cannot check

4x4 and AWD have a higher tow rating due to better traction

I had a constant 4wd disco and they do feel better at towing more in contact with the road would be the way I describe it but that should not be the determining factor that enables an increase in towing capacity. Probably more to do with the tare weight, the construction of the chassis, drive train and that manufacturers are willing to increase towing capacity just for the sake of selling more vehicles.
I've had a couple of GQ patrols over the yrs amongst a lot of other vehicles they have one of the strongest drive trains, chassis in their class, 4 wheel disc brakes but are only rated to tow 2.5t which is 300kg under the gvm of the vehicle. But when you think about it it's a lot safer to tow something that is less than the weight of the tow vehicle especially with so many people these days having no idea what there doing and buying the biggest van they can and towing for the first time without any guidance.
You want to be in control of what you're towing and not the other way around especially if the unexpected happens like a brake failure on whatever item your towing. But I expect lots of people believe that will never happen.
Also I don't believe in towing aids that are just there to cover up the truth that your vehicle is actually towing beyond it's actually capabilities or poorly loaded but manufacturers love them because money first safety 2nd. They convince so many nieve people every year that they need these devices and wow some people you meet when traveling are so brainwashed into believing you cannot tow safety without towing aids. If just some of them tried towing without these aids they would soon discover how poor their set up is then they may actually learn something instead of blindly driving down the road holding up traffic.

So true RMD
And add to that the situation where some tow hitches move the pivot position even further aft. It seems to me that those hitches should have a corresponding reduction in tow ball down load rating. That does not seem to be the case though.
Roy

Because of this overhang you see a lot of Tritons with broken backs especially in place like Cape York with many dips and corrugations.

It is not so much the design of the Tritons that are the problem, it is how they are loaded and driven. Even the Landcruiser Troopies are subject to it. Ron Moon interviewed three outback mechanics that have done a lot of repairs to vehicle chassis to get them home. Read his report - What causes a ute chassis to bend?

Nomadic Navara
It IS the design of the Tritons. More have bent chassis or broken backs than ANY OTHER BRAND by a long chalk. I have a pic somewhere of 5 Tritons with broken chassis which were overloaded for sure by carrying slide ONS, but they failed as could be predicted.
You watch ANY Triton from behind and see how much the tail flicks up and down compare to any other ute. Hardly good to have happening
Tritons don't have good shocks to cater for trailed loads either. Most utes don't.

I had to recover a Triton once, and on the trailer it danced uncontrollably with wheels tied down at 40kmh. We had to tie the whole body t the trailer to be anywhere near safe. Low KMs but shocks were totally stuffed/not working.

RMD, you are contradicting yourself here. You said "I have a pic somewhere of 5 Tritons with broken chassis which were overloaded for sure." Please show me a picture of a Triton (or any other ute) that has a broken back that was not overloaded?

The design of the Triton may make them less tolerant to damage due to a little overloading than other models. However, that does not mean they are liable to break their backs when they are not overloaded, unless they are driven by people who drive them outside the bounds of reasonable drivers. Any ute can have their backs broken by overloading or extremely rough handling.

99% of the time a chassis snaps or cracks is operator error, neglect or ignorance as to how to sensibly load a vehicle. Just have a real good look at some of the pics on the net and see how much weight they have over and beyond the rear axle then some add a boat to the tow hitch and blame the vehicle for their neglect. Lots of the picks you see blame air bags as well because they don't know how to correctly use them.
If you want or need to carry a lot of weight on a dual cab a chassis ext will quite often help centre the weight and save you money and time spent broken down in the middle of nowhere. It also gives you extra room under the tray to fit tool boxes etc to help keep center of gravity down.
Also never hang spare wheels off the back they and a lot of stress to the chassis just in front of the leaf springs on any vehicle and makes the steering lighter which should be an indication that you are incorrectly loaded. Put them under the tray or near the headboard.

Have you got a scangauge or similar installed ? If not why not ?
What you are implying is the Prado shouldn’t be towing anything !
But you did say YOU killed the motor !
Did it overheat ? If you didn’t have a scangauge or similar, how did you monitor engine temps ?

Happy Ex
I don't think you did anything wrong but earlier Prados and Hilux have a reputation for cracking pistons. especially if they have done a few KMs and injectors are not spraying properly, cleanly and same as other cylinders.
It is far better to have the transmission in a lower gear in any arduous work so the engine revs a little more and eases the instantaneous heat load being produced in the cylinders. Many want them to pull and use torque but that as means more heat and pressure values in the combustion chambers. More revs allows the heat to be exiting the engine and it is under less load then too.
Most of these vehicle and dual cab utes are made for on road comfort and not for handling and load carrying ability with a trailer attached. Improvement can be made as you know.
Heavy vehicles often have to drop a gear or two and rev faster so the engine doesn't overheat. Fans turning faster get rid of more heat at slower speeds.

In reply to Gronk
Yes I have an UltraGauge. I would not tow without one. I pointed this out strongly in another thread on this forum recently. What I like about the UltraGauge is that one can set alarms to avoid the need to visually monitor these readings constantly while driving. Changes happen quickly as you would know and it would be easy to miss the change in numbers on a small screen. I have the engine temp warning alarm set at 100 deg C and it did not activate and there were no signs of engine overheat when I stopped.
I guess I did kill the motor as it is my car and I was driving it at the time. When towing I am always the driver so I take the responsibility.
No I am not at all implying that Prados should not be towing anything but they do have limitations once getting close to their rated limits.

In reply to RMD
You are right, the earlier Prados do have a reputation for same. Mine is a 2013 3l with almost 200k on the clock. I also believe it would be one of the ones they produced with piston oil flow issues that did not allow for efficient oil cooling to the back of the pistons. Problem is I have not been able to clarify what pistons are in the new motor Toyota sold me. I expect the injectors were also contributing as they were original. New injectors now. Interesting that it is always #3 piston that fails. Mine had #2 and #3 cracked and a hole then blew out in #3.
I only ever tow in 4th. for the reasons you outline. It is also important to be monitoring the transmission temp as well, as mine at least, can reach fantastic TC temperatures if slipping on long up hills. That was covered in depth in the other recent thread also so will not get dragged into that again here other than to say transmissions also factor into the towing limitations. I also have alarms set on both transmission pan temp and TC temp and none were triggered. I can only assume that in this instance the TC was locked and I was in an appropriate gear to have all temperatures within their safe limits. Experience tells me that if the TC is locked while holding too high a gear then the motor over load will quickly cause the engine to overheat. This does not appear to be the problem in this case. I feel you are right about getting that heat away from the cylinders quickly and that is one reason why I am looking at exhaust upgrades now. A free flowing system must surely help draw that hot exhaust gas away more quickly. Can't hurt anyway I am guessing.
Yes the Prado at least is lovely to drive when empty or even moderately loaded but once getting close to its upper limits it falls short in many areas. Can't speak about other makes and models but I expect most would be similar.
I have driven enough trucks and semi-trailers to know you are absolutely right with your last statement about gear selection and engine revs. This applies equally to tractors which I also have a lifetime of experience with.
While at it I will comment on the buildup of soot in the intake chamber. Previously I had removed the intake manifold and cleaned it. There was buildup but not detrimental so stopped at the rear elbow that is almost impossible to get off without removing the engine. I was relying on a can of cleaner inserted at each service to do the rest. It was like black toothpaste so thought the cleaner would dissolve it ok. On removing the motor now, I was told that there was only a finger size hole in the manifold and I was surprised to see the huge buildup of soot actually in the inlet ports. Clearly the spray cleaner is a waste of money. This build up I expect would have been messing with the air flow in and probably caused a richer fuel/air mix in the chamber which would not have helped the situation either. This too is about to be looked at with the new motor.
Vehicle stats:
199,000 km on clock
46,000 km towing 2.2t van
The rest general city/country driving with a bit of light off road adventuring.
Roy

Think carefully about the exhaust upgrade as it can lead to over boost, theoretically contributing to piston failures.
Interesting what you say about it always being cylinder 3 that fails, that alone rules injector faults out.
It is a very controversial topic with a lot of misinformation circulating about it but my belief is if there was an injector failing it would show up in the correction values would it not? There is a lot of fear mongering about regular injector replacement even if the values are in spec.

If you search PradoPoint for "cracked pistons" you will quicky discover how often this occurs with 1KD engines use for towing. My reading of the discussion is that injectors are no longer regarded as the cause. There were faulty pistons. In support of this, a number of people have had support or compensation from Toyota.

Actually blowing a hole in a piston sort of indicates there was a degree of uncontrolled burn and heat being developed by poor injection and the already soft and pliable piston crowns were simply blasted through. Cracks are one thing, Holes are another.

Peter.
Nice to see someone who knows what a Septic Tank is!

Thanks 3 ways,
That's exactly the sort of thing I was thinking.

3ways - Which reply were you referring to? If you are going to comment on someone else's reply, use the Follow-Up button. If you start a new reply, we do not know which of the above replies you are commenting upon.

Pretty sure he was replying to the original post seeing he is the only person to actually answer the question in it.
However it is a very informative thread never the less.

G/Day Batts

Wasn't Mobil Gear oil by any chance was it?

Cheers Axle

Castrol oil

Another example of where an Ultragauge or Scangauge is necessary when towing.

Ok thanks good idea I'll do some research on them. I'll definitely look into getting something to monitor the gearbox oil temp but when I get closer to retiring and get another pop top van.

Perhaps, BigFish could explain to people how the Ultragauge can rear manual gearbox temperature when there is no sensor on the manual boxes for temp. So , does the owner try and source a temp sensor and somehow have it reading on the Ultra/Scan gauge via OBD port. Come on, fess up>

Candace, I would expect more problems here with bent chassis on utitliies as they mostly occur on outback tracks. Do the Yanks have the same amount of long, rough bush roads as we do?