I own a 2009 Fortuner V6(1GR-FE) with an A750f 5speed gearbox. (Out of interest A750f – Auto Seventh generation, Five Speed, (f)Four wheel drive) Where the D4D’s make use of A340f gearboxes.
Now seeing as it is a ‘sealed’ unit, which is bull. I read up on replacing my Oil. The manual stated that Oil must be drained off and checked at 42Degrees if memory serves. That done and dusted with new oil/strainer and gasket. I soon realized that if the vehicle indeed measures the oil using its OBD2 port, I should be able to measure Oil temps myself. Two sensors, one in the pan, one after the torque converter.
Purchased myself a VieCar4.0 Bluetooth scanning tool (R400), after the BlueDriver(R1200) could not input PID inputs. Now this is specifically for the A750f inputs, many others are available on the internet. I downloaded Paid software (iOS) named ‘Car scanner’ – Android (Torque Pro) and used the following parameters:
For the transmission pan temp:
Pid: 21d9
Min: 0
Max:100
Symbol: °C
Equation: (((((E*256)+F) * (7/100) – 400)/10)-32)÷1.8
For the transmission converter temp:
Pid: 21d9
Min: 0
Max:100
Symbol: °C
Equation: (((((G*256)+H) * (7/100) – 400)/10)-32)÷1.8
Bringing me to a point where I can now measure my own Transmission temps using my phone. After playing with the App, you can set various parameters and upper and lower limits to warn you in time.
So with all this info in hand I soon realize that my Transmission Oils Runs at higher temps than what I am comfortable with. More reading on the internet I realize that WS(World standard) Transmission Oil sits comfortably at 85 Degrees, Preferably at 65 Degrees, not trying to exceed 95 Degrees for long periods of time… Toyota being idiots in this regard, only have the A/T warning light come on at 149 Degrees, whereby your clutch plates are definitely already glazed up, Oil burnt, an possible damage done. Those interested in oil temps and degrading - there is a lot of info on the internet...
So next Rivertrip,2021, (now with ONCA bumper fitted) I start to look for temperature issues. Only to realize that temperatures seem fine in the beginning, but about 2 hours into the drive and sun coming up, temperatures quickly escalate into figure above 100-110Degrees constantly. Cooling down on the rocky sections to 90 Degrees and going up to 115 Degrees in sand. Even saw 120Degrees sometimes. And yes I did make a point of it to lock up the torque converter where possible. Not only does the A/T oil temps rise, but the water temps also start rising to close to 100Degrees, where they should be sitting at 88Degrees ranging to 92 Degrees when working hard.
Back to google and learning more… The Fortuner, and most ‘newer’ vehicles make use of a Shell and Tube heat exchanger, which is basically a tube that is situated at the bottom(or side) of your existing radiator(submerged in water) that serves two purposes, firstly heating up the transmission oil to a good operating temperature(which is not really a problem in south Africa), and then when it has reached the temperature, the idea is that the water in the radiator will absorb the heat again and cool it down (radiators are very efficient in most cases for cooling). So getting back to the problem, everything started making sense. The A/T has 12l of oil in the system. Once I set off driving under more strain than what is usually used, the transmission oil starts heating up, as it should, then starts to heat up to an extent where the radiator should start cooling it, but does not have enough convection to absorb all the heat and the oil temps start rising, secondary to that after 2 hours or so driving hard, or towing the water temps start rising as the radiator is also now heating up to an extent where it can no longer cool everything down. Intake temperatures are rising, Oils temps are rising and then lastly water temps are rising, bad cycle repeating itself.
Now addressing the issue, I know the Prado’s and Mitsubishi Have external coolers fitted to them. So I decided to give these a go. I ordered myself a Hayden 679 Oil cooler from ‘All-O-Matic Transmission’ in Jo'burg – Great service, next day delivery with card facilities – wow!
Thus there are a few choices:
1. Leave current systems as they are – More than enough when doing normal city driving, towing smaller loads etc…
2. Make use of the external cooler only, thus losing any heating element in winter
3. Use both system(My Chioce) where the oils runs from the gearbox to the original Shell and Tube, then in series runs to the external Oil cooler, then back to the gearbox.
In many parts of the world this system is known as a towing upgrade, actually offered by dealers – but why do this in SA??? The faster something breaks the faster you can bullshit them into buying a replacement one, and blaming them for not looking after their vehicles…
Installed and ready before Rivertrip 2022 – Now also with larger tires. Conclusions are found that this has OVERALL decreased my temperatures with about 25 Degrees, putting me right back into the sweet spot I want to be! A/T oil temps never exceeding 100 Degrees (even in overdrive). And finally coming to a point where my A/T oil stay constant and my Water temps rise –DUE to engine working itself to death and not the oil rising the water temps! As soon as I back down the water jumps back to a beautiful 90Degrees almost instantly! All and all a win in my books and can now go back to playing as hard as the motor will allow me without having to worry about A/T oil temps…
Overall: R400 OBD scanner, R 2000 oil cooler, R500 Oil topup, Piece of mind - Priceless
Some photos below…
Some might argue the fact that why not just buy a manual... So many people doing upgrades on vehicles - Manual. worry about diff ratios, transfer case reduction gears, etc etc... Al things which I can control with a torque converter. Also makes my daily commuting much nicer... I have full control over obstacles, and the only thing to 'worry' about is the auto-box. This has now been partially solved in my opinion...
Scroll past if this is of no use to you...
