Max D4 SDV6 safe transmission and coolant temperatures while towing

[shadzta]

Hi guys, owner of a beautiful 2015 D4 SDV6 coming from a 200 series Sahara and have learned so much from this forum.

I have a question regarding maximum safe transmission and coolant temperatures while towing.

My SDV6 has 85k kms on the clock, had transmission serviced with life guard, towed from Sydney to Vic HC and back. On the way back on the Hume HWY in 40-45 degree heat towing about 3.2 tonnes I notice coolant temp needle reached just under the hot mark on a slight incline. I connected the Gap Iid tool to monitor the transmission and coolant temps.

Transmission was between 106-110 degrees celcius and Coolant was between 110-112, I was barely touching accelerator to keep it at those levels, any increase in load and it would climb to 115, i noticed the needle reached just under hot mark when at 115 so would slow to keep it around the 110-112 mark.

Speed was between 90-100kms.

I then received a low coolant level warning and pulled over to the nearest service station after a minute. (luckily)

Found out the top radiator hose had been slit from rubbing on the engine cover. Apparently a common problem. Rang LR dealerships who advised no dealership in Australia has one! Luckily managed to source one from an independent in Burwood and got an Uber driver to deliver it. Yes, long story, but Uber was able to deliver my part 2 hours into country from Melbourne.

Anyways, after installing it needed about 3 litres combined coolant and water poured while engine running and heater on max.

Temps remained generally the same as above after driving. Towing in D or S made generally no difference.


When the weather temp dropped to 30 degrees I was averaging 105 on both tranny and coolant temps.

Question is a: what is the max safe temps to run,
b: what is everyone else getting while towing in similar heat and
c: is this considered normal levels or should I be getting something checked out? The reaching just under hot mark has got me worried to do any outback touring.

Thanks in advance!

[BradC]

In mid to high 30s ambient I get coolant just over 100 and oil ~102 on the flat, and up to 115 screaming up a big hill going as hard as it'll go. I've never seen the temperature gauge budge from 50%. My van weighs less than the car though, although it has the aerodynamics of a small block of flats (not unlike the car).

At the coolant cap pressure of 16psi, water boils at ~122C, so regardless of glycol content I'd want to be keeping it fairly well under that.

Cant help with the transmission though.

[DiscoJeffster]

The coolant gauge on the dash will never move under normal use, including towing even in hot climates. It’s designed to maintain the same position under normal operating temps which includes towing. The fact it moved for you was a clear indicator of a problem which became apparent not too much later. Honestly, you don’t need to worry, just drive it and take note of the errors. The gearbox temp is aligned to the coolant as it uses the engine coolant as a cooler - so it will be similar temps.

[shadzta]

Appreciate the quick responses gents. The thing is it reached just under high again when temps hit 115-116 degrees AFTER I did the repair. And that was up a long slight incline but only just pressing on the accelerator, maybe 20% accelerator. What I'm afraid of is if I were to climb Mt Ousley near Wollongong for those familiar with that road and Ill need to give it 75% to 100% accelerator it will definitely over heat as it's a punishing long incline over a few kms.

Will definitely be doing a full radiator flush. When I removed the top radiator hose the water appeared brownish green and not pink as per the coolant colour. Not sure if that means anything to those more mechanically minded than myself.

[BradC]

When I removed the top radiator hose the water appeared brownish green and not pink as per the coolant colour. Not sure if that means anything to those more mechanically minded than myself.

I had a pinhole leak in one of the EGR cooler hoses and the coolant coming out of that looked for all intents and purposes a dirty brown/green, yet the freshly flushed and filled coolant in the bottle was the as-supplied orange colour. I dunno what is in that coolant, but I had to collect a bit in a test tube from the leak to convince myself it was actually the same stuff I put in. It only looked the right colour in sufficient quantity, in the right light and with transmitted light rather than reflected. Odd stuff.

[DiscoJeffster]

Appreciate the quick responses gents. The thing is it reached just under high again when temps hit 115-116 degrees AFTER I did the repair. And that was up a long slight incline but only just pressing on the accelerator, maybe 20% accelerator. What I'm afraid of is if I were to climb Mt Ousley near Wollongong for those familiar with that road and Ill need to give it 75% to 100% accelerator it will definitely over heat as it's a punishing long incline over a few kms.

Will definitely be doing a full radiator flush. When I removed the top radiator hose the water appeared brownish green and not pink as per the coolant colour. Not sure if that means anything to those more mechanically minded than myself.

If you didn’t have the IID tool you’d be none the wiser. Turn off the tool and just drive it. Presumably after fixing it the temp gauge was stable? You’re fixating on numbers you have no idea on to be frank. If you see the temp gauge move then you have a problem to be concerned about. If that’s the case I’d presume it’s not repaired correctly eg has a leak still or has an air pocket etc. trust the temp gauge. The factory knew what temps it can handle before indicating a problem.

[gavinwibrow]

If you didn’t have the IID tool you’d be none the wiser. Turn off the tool and just drive it. Presumably after fixing it the temp gauge was stable? You’re fixating on numbers you have no idea on to be frank. If you see the temp gauge move then you have a problem to be concerned about. If that’s the case I’d presume it’s not repaired correctly eg has a leak still or has an air pocket etc. trust the temp gauge. The factory knew what temps it can handle before indicating a problem.


The hopefully attached extracts from the Ashcroft site may help with part b of your questions. Visit their site for fuller information.

I know that the TD5 can operate up to 120C, but can't help with the V6 versions I'm afraid.

I too like to keep an eye on these things, especially when heavy towing, and don't subscribe to the "she'll be right mate" approach recommended by some.
Happy travelling

[DiscoJeffster]

The vehicle will tell you when the transmission is operating beyond it’s designed temperature with a warning on the screen, something akin to “transmission overheated/over temp”.

[Eric SDV6SE]

Hi
Appreciate the quick responses gents. The thing is it reached just under high again when temps hit 115-116 degrees AFTER I did the repair. And that was up a long slight incline but only just pressing on the accelerator, maybe 20% accelerator. What I'm afraid of is if I were to climb Mt Ousley near Wollongong for those familiar with that road and Ill need to give it 75% to 100% accelerator it will definitely over heat as it's a punishing long incline over a few kms.

Will definitely be doing a full radiator flush. When I removed the top radiator hose the water appeared brownish green and not pink as per the coolant colour. Not sure if that means anything to those more mechanically minded than myself.

As per DiscoJeffster, the gauge will only move if you have a temperature issue, and the engine management system told you low coolant and you did the correct thing.

Well done on getting the top hose replaced, hope you’ve modified the engine cover to give it extra room, otherwise the same will happen again.

High temp after your roadside repair would indicate either trapped air or incorrect coolant concentration, but the engine should still be in the “safe zone”, otherwise the low coolant or other over temperature messages would have appeared.

I would also do a complete flush with the correct coolant concentrate mix and ensure all trapped air is removed via both air bleed valves, one at the engine end, coming off the coolant outlet, the other at the coolant overflow bottle.

Coolant should be bright red / pink, any other colour indicates overheated coolant, so it’s done it’s job.

I’d also disconnect the hoses from the transmission cooler and drain, then reconnect and flush the entire system with demineralised water, then refill and bleed all air from the system.

I’ve towed our van through 38-40 deg temps at 100-110 kms with no coolant issues in the 5 years of ownership, my temp gauge has never moved past halfway in 100,000kms.

Hope this helps,

Eric

[101RRS]

I too like to keep an eye on these things, especially when heavy towing, and don't subscribe to the "she'll be right mate" approach recommended by some.


It is a not a "she'll be right mate approach" as the driver does not need to keep tabs on what is happening - the ECU does that and if the engine gets too hot, in addition to the visual indication on the gauge the ECU will flash up a message, the red engine light will and most likely the ECU will shut the engine down to protect it. Same with the gearbox.

So in these vehicles doing all this individual monitoring is pointless - as mentioned you would be never have know there was a problem because there wasnt - if there was the car would let you know as it did when there was low coolant.

[DiscoJeffster]

It is a not a "she'll be right mate approach" as the driver does not need to keep tabs on what is happening - the ECU does that and if the engine gets too hot, in addition to the visual indication on the gauge the ECU will flash up a message, the red engine light will and most likely the ECU will shut the engine down to protect it. Same with the gearbox.

So in these vehicles doing all this individual monitoring is pointless - as mentioned you would be never have know there was a problem because there wasnt - if there was the car would let you know as it did when there was low coolant.

Thank the lord for someone else with commonsense. For a moment I thought the sixties were calling and they want their carby, sensor-less engines back. I was beginning to question my attendance here if we’re all going to start driving our cars with ballet slippers, stopping every 2km to let the engine “cool down”. Trust the car. It knows what it can handle.

[Milton477]

Good question & one to which I have often wondered what the answer is.
These are the kind of temperatures I occasionally see & I always back off the power when they occur. I always watch the Viscous Fan to see when the system is running out of cooling option.
My vehicle is a MY15 TDV6 & has done 81K with a gearbox service at 60K.
My van weighs close to 3 tons & I tow in Sport mode with Cruise Control 90% of the time.
To better maintain speed, I use the gearbox paddles to help select the correct gear before my speed slows.

147246

[shadzta]

Appreciate all the responses gents and I accept some people like to know specific temps and others are more than happy to wait until a warning appears. Each to their own.

Note I didnt connect the Gap tool until I noticed the temp guage reach just under hot.

The benefit of monitoring is that I knew that at exactly 115 degrees is when the needle would move to just under hot. If I wasn't monitoring I would have no idea and would not have been able to adjust my throttle accordingly to keep it in the safe zone. Id much rather that and be able to drive 8 hrs home than wait for an overheating message and possibly do irreversible damage.

So there you have it. 115 degrees is when the ecu picks up the start of overheating range.

After blowing my turbo while towing full pedal up a hill in my 200series I like to keep an eye on things these days. At least until Ive reflushed this system and retest.

[PerthDisco]

Note I didnt connect the Gap tool until I noticed the temp guage reach just under hot.


Just to fully understand I assume the red light did not come on when the needle went up?

This would indicate that the needle could raise another step with the red light to indicate a catastrophic temp rise?

[101RRS]

Note I didnt connect the Gap tool until I noticed the temp guage reach just under hot.

While I certainly stand by my post above - it is important to know your car and respond to indications presented to you - and I agree with you if I saw the temp gauge rising, even though there are no other indications, I would be wondering why and starting to check - I know that in an car with a basically good cooling system the gauge will sit around normal through the acceptable operating heat range and will only rise if something is up even if the temps are still within acceptable sensor temps. I would go looking why - in my experience it is normally a slow leak as with a catastrophic failure the gauge will stay on normal as there is not hot coolant around the gauge sensor.

You used you Gap tool and got temps - I dont have a Gap tool but have some experience in this and know that the coolant on hot parts has a particular smell - so for me it would have been up with the bonnet and off with the engine cover and started "sniffing" and looking. This would probably detected your cut hose. You Gap tool gave you temps but to me 115 is a little highg but given the outside temp and what you were doing didn't help - it was not until coolant had dropped enough to trip to coolant level sensor that highlighted the actual issue.

Now if you had not used the Gap tool and I did not lift the bonnet we both would have continued on suspicious that something was up based on the temp gauge - the first indication would be the low coolant message, if we ignored that all the other systems would have kicked in.

You did the right thing and checked and you still have a good engine, how many times do we read on this and other forums that the dash board lit up with overheat information but I continued on to the next service center - and a dead engine.

I have a low coolant/hot engine alarm on my 101, the equivalent for my air cooled Haflinger and I am seriously considering a Engine Watchdog for my RRS because irrespective of what we have discussed here, none of the car's systems are likely to protect you if you have a catastrophic loss of coolant at freeway speeds - the first you will know is when the dash lights up with an associated death rattle from the engine with the temp gauge still sitting on normal - with no coolant in the engine the systems will pick it all up too late.

Garry

[shadzta]

Just to fully understand I assume the red light did not come on when the needle went up?

This would indicate that the needle could raise another step with the red light to indicate a catastrophic temp rise?

No the red light did not come on so yes may have a few more degrees until overheat but didnt want to push it to that. The gap tool allowed me to ensure i didnt push it to 115 with accuracy.

[Meccles]

Not a D4 I know my mates BT 50 Mazda 2016 model has just had auto replaced under warranty at 60000km it failed he fitted a scan gauge as he tow’s he found his gearbox temps were rising very quickly on any hill Mazda don’t recommend separate tranny cooler but the advice from independent shops is to fit one as soon as it’s out of warranty the Ford gearbox apparently has issues. Whereas in all the threads on this forum not once has anyone needed to fit a separate tranny cooler so assuming cooling system is not faulty looks like LR/ZF got this right

[vbrab]

I thought my D3 trans was getting some level of cooling through the radiator, and seems to have survived quite well thus far (and my D3 runs much cooler than most as have had EGR's removed), but figure a separate cooler might help trans run even cooler.
Always happy to make it easier on the trans, as I work and drive in central Australia.
Has anybody fitted a separate trans cooler to a D3-4, and any suggestions on what brand/type if fitted?

[SeanC]

I thought my D3 trans was getting some level of cooling through the radiator, and seems to have survived quite well thus far (and my D3 runs much cooler than most as have had EGR's removed), but figure a separate cooler might help trans run even cooler.
Always happy to make it easier on the trans, as I work and drive in central Australia.
Has anybody fitted a separate trans cooler to a D3-4, and any suggestions on what brand/type if fitted?

When I was waiting to pick up my vehicle, another D3 owner who towed a large caravan was talking to one of the mechanics about fitting a second transmission cooler.

While over at Moreton Island along the western beach, I was surprised that the transmission temp got to 98C. Sand was damp and a bit soft, maybe sinking in 4cm and doing 50 km/hr. Highway driving in summer not towing, it gets to about 80C.

[DiscoJeffster]

When I was waiting to pick up my vehicle, another D3 owner who towed a large caravan was talking to one of the mechanics about fitting a second transmission cooler.

While over at Moreton Island along the western beach, I was surprised that the transmission temp got to 98C. Sand was damp and a bit soft, maybe sinking in 4cm and doing 50 km/hr. Highway driving in summer not towing, it gets to about 80C.

Given in “cools” itself with the same coolant as the engine, it’s reasonable to expect similar temperatures as the engine. Again, they designed it like this in conjunction with the gearbox manufacturer so we are in a reasonable position to trust their judgement surely?

You actually run the risk by using a separate cooler of not getting the oil up to it’s designed operating temp and doing more harm. Cold oil isn’t good necessarily good oil.

[vbrab]

First thing I noticed on having the EGR's removed was that engine takes long while to heat up (took car back as I was worried, and service guy said that was what everybody without EGR's came back and queried), and temp gauge NEVER goes about halfway marker (and I drive in hottest of conditions with aircon running, towing 7 meter trailer, and at speed usually).
What I also notice is that if I park up in very hot conditions on a long trip and leave engine running, that the temperature drops markedly on the gauge.
can leave it parked and running in 50C with aircon running and the temp drops to about a quarter on gauge.
SO I figure that the EGR;s add considerable heat to the cooling system, and removal is probably the best way to keep engine (and trans) cool.
I did notice that when temp was about 2C (at night), that it took about 10 k's before car hit operating temperature (once I was up and cruising temp went up to mid range marker), so perhaps not a positive in very cold areas.




Given in “cools” itself with the same coolant as the engine, it’s reasonable to expect similar temperatures as the engine. Again, they designed it like this in conjunction with the gearbox manufacturer so we are in a reasonable position to trust their judgement surely?

You actually run the risk by using a separate cooler of not getting the oil up to it’s designed operating temp and doing more harm. Cold oil isn’t good necessarily good oil.

[TDV6]

I have fitted an additional tranny cooler and have an "Engine Watchdog" gauge as well as a "Scanguage" fitted to monitor what's going on. I have a 3.3ton van that I have towed to Adelaide through 43 degree heat at Broken Hill several weeks ago, I constantly monitor what is going on with my car and adjust my driving style to suit the conditions prevailing. This last trip I had a strong headwind on the SA border down to Adelaide so I dropped from my normal 93-4kph down to 84-5kph to keep engine temp around 100-105 and tranny below 100.

I have removed anything in front of the radiator that can divert the airflow (lights and winch control) as I found this to have the greatest affect on temp of engine or transmission. I once tried towing the van up the Toowoomba range in low range, it was a disaster, I pulled over and let it idle for 15-20min to get it to a reasonable temp, then set off in high range up to the legal 60kph and after that the maximum temp was 107-8 from memory.

My 2005 D3 has 313k and has towed the van 150 to 200k.

Ryall

[DiscoJeffster]

Ryall, have you ever risked it and run at 110 degrees? Felt the thrill of it? I went to 120 once and my god, it was like being on crack. You should try it - you haven’t lived until you do.

[Hugh Jars]

I owned (I’ll admit it) an MY14 Grand Cherokee, which has the 8 speed ZF box. Jeep had installed a separate trans cooler standard to this model.

When I owned it, it ran at 93 (normal) and 96-98 (towing).
I don’t know what the D4 runs at. I reckon into the low hundreds wouldn’t be a problem.

[BradC]

You actually run the risk by using a separate cooler of not getting the oil up to it’s designed operating temp and doing more harm. Cold oil isn’t good necessarily good oil.

I used to believe this also until I read an excellent writeup by a Ford transmission engineer that categorically debunked this complete with comprehensive thermocouple data. Once I read it, it made complete sense. I'll have a look and see if I can find a copy.

The in-radiator transmission cooler sits in the cool side of the radiator, or the transmission cooling flow (for an in-transmission water cooler) always comes from the cool side of the radiator.

This is *always* cooler than the fluid coming from the transmission, even just after startup. Think about it. The radiator gets heated by the engine via the thermostat. So the fluid in there is at ambient up until the engine is warm enough to even open the thermostat. Then it's bleeding coolant into the hot side of the rad. By the time it gets to the cool side of the rad, its considerably cooler. The radiator cooler *never* heats the transmission fluid under any circumstances. Remember the fluid entering the cooler is the hot fluid straight out of the torque converter, not the cooler bulk oil in the sump.

The fluid/fluid heat exchangers are also considerably more efficient from a surface area perspective, so they are sized as required (relatively small). It takes a considerably larger air/oil cooler to effect the same cooling as the in-rad unit. Best effect for an add-on is to fit a smaller air/oil transmission cooler in series with the in-radiator cooler depending on your specific deficiency to either pre-cool the fluid entering the radiator or supercool the liquid leaving the radiator. As any heat exchange is based on the log mean temperature difference over the two sides, you'll always get best bang for your cooler area by using the air cooler to take the hot fluid straight from the transmission. On the cool side you'll need a much bigger HX to remove the same amount of heat.

[DiscoJeffster]

Hey Brad. Thanks. You know I started to think along these lines myself as to what temperature the bottom of that rad is - Eg how much temp reduction happens from top to bottom. Also was going to review if there’s any thermostat control.

[Lukeis]

Until two weeks ago ive never heard of a transmission cooler as an after market necessity.

Later this year year I will be travelling for six months around the eastern half of Aus towing a 3.2ton off road (ie high) caravan. We’ll be spending three months of that in the top end and up the middle from Adelaide to Darwin so I’m expecting hot temperatures.

I see above Riley has fitted this to his D3 but has anyone fitted one to a D4? Or felt the need?

trying to avoid the above - she’ll be right approach but also keen to avoid unnecessary costs and changes to the car. If anyone can lay it out for me straight

its a 2011 d4 - 2.7L

[BradC]

trying to avoid the above - she’ll be right approach but also keen to avoid unnecessary costs and changes to the car. If anyone can lay it out for me straight

Back before the invention of lockup converters an auto towing generated a *lot* of heat. Provided you can keep the trans locked up they just don't generate the heat they used to as the converter is really not doing much other than sloshing some oil around. Put the boot in going up a hill and drop it out of lockup though and you might need to get rid of some extra heat.

Heck, if I tow the van in my 4 cylinder auto Volvo (which only locks up in 4th) and don't go fast enough to get it to lock up, even *with* an aux cooler I can see trans fluid temps > 130C going up any sort of grade. If I can get it to lock up that drops to about 105C.

I'm led to believe the ZF boxes are pretty impressive about how little energy they burn as heat, but if I had an auto Disco (which I don't) and towed a 3T+ van (which I don't), I'd probably be either looking for an aux cooler *or* changing fluid more frequently (or at the cost of ZF fluid probably getting it tested). Heck, my D3 which was specced for "Tropical countries" has a factory fitted aux cooler on the post-radiator coolant going to the *fuel* cooler. None of the landrover places I spoke to had ever seen one, let alone knew where to get one. Yay for LR-Direct.

[DiscoJeffster]

Towing is so intense for the box, it’s unsurprising that so many fail before the standard 230,000km claimed interval, but to be fair, LR does state that towing is arduous use and means additional changes. Unfortunately the dealer doesn’t know what you do with it between services so doesn’t prompt.

[gavinwibrow]

Back before the invention of lockup converters an auto towing generated a *lot* of heat. Provided you can keep the trans locked up they just don't generate the heat they used to as the converter is really not doing much other than sloshing some oil around. Put the boot in going up a hill and drop it out of lockup though and you might need to get rid of some extra heat.

Heck, if I tow the van in my 4 cylinder auto Volvo (which only locks up in 4th) and don't go fast enough to get it to lock up, even *with* an aux cooler I can see trans fluid temps > 130C going up any sort of grade. If I can get it to lock up that drops to about 105C.

I'm led to believe the ZF boxes are pretty impressive about how little energy they burn as heat, but if I had an auto Disco (which I don't) and towed a 3T+ van (which I don't), I'd probably be either looking for an aux cooler *or* changing fluid more frequently (or at the cost of ZF fluid probably getting it tested). Heck, my D3 which was specced for "Tropical countries" has a factory fitted aux cooler on the post-radiator coolant going to the *fuel* cooler. None of the landrover places I spoke to had ever seen one, let alone knew where to get one. Yay for LR-Direct.


At the risk of remaining off topic, I have a D2 auto and tow 3.5T. I have an Auto Trans R Us (Balcatta) ATF front mounted cooler, and to date have done 275K km without any apparent extra wear (touch much wood) or high operating temps. In fact my non towing urban operating temps are generally well under the 60-65C I occasionally get to under heavy towing, and which according to Ashcroft's is actually lower than preferred, so I was pleased to hear about the Ford experiment/research. I did purchase a Derale ATF thermostat to facilitate extra oil warming, but have not fitted it and becoming less likely to each day.

[BradC]

well under the 60-65C I occasionally get to under heavy towing, and which according to Ashcroft's is actually lower than preferred

Wow. Ok, so I fitted an external thermostat to the Volvo because the old AW box doesn't have one and with an Aux cooler in winter driving around town unloaded the oil never warmed up. I was under the impression that most boxes made in the last 20 years had cooler thermostats built in.

If those are your bulk trans fluid temperatures then yes, I'd fit the thermostat. While I said the radiator *never* imparts heat into the fluid under running conditions it's never going to pull the fluid temperature as low as your cooler can as once the thermostat is open even the cold side of the radiator will be considerably above ambient. It sounds like your cooler is quite impressive and is quite capable of over-cooling the fluid, so a thermostat sounds like a good idea.

There's 2 reasons. First, the obvious one is cold oil is thicker and some of the anti-wear additives work better with a bit of heat.
The other isn't as obvious until you think about it. While the transmission is effectively a "sealed" hydraulic circuit (unlike a crank case for example), the fluid still expands and contracts (a lot). This draws moisture in, and getting the fluid up to temperature speeds the process of the fluid rejecting the moisture.