2012 Mazda BT 50 Transmission

G'day Ian
Most vehicles are made with enough reserve cooling capacity to cover most of the normal situations, however it seems, like many people, it is easy to begin to go past the ability of the vehicles cooling performance.
A 30-40 degree day, we have them in OZ, and also uphill will quickly raise the temp of the auto past what you have experienced. I agree, not good.

When a hot day & the engine is working towing the weight behind it must be bearing the normal running ability of the cooling system. With the auto dumping more than normal heat quantity into the bottom of the radiator it is heating the radiator water.
If the engine has already brought the heat at the bottom of the radiator to a critical level then there isn't any insurance room to cater for the load/auto heat factor and a sudden overheat can happen. That means a means an additional cooler is essential.

The hot fluid leaving the auto is best cooled before it gets to the radiator so the volume of heat isn't going to try and overheat the already "working hard" engine cooling system.
Because the auto fluid is hottest as it leaves the auto, it has the highest differential to the ambient and so the cooler placed there will dissipate the most heat if it is in a suitable airflow.

I think the oil subjected to high temps does need to be changed more often than makers say.
On another forum, Recently one Mazda dealer happliy sold fluid to a customer in 1 litre bottles at $46 a bottle. Another member had changed his fluid and he paid $21/L for the same stuff, so beware and do homework before paying for auto fluid for these.

Cheers
Ross M

This has been previously discussed. 107 deg C (225 deg F) is approaching the temperature where potential transmission damage is likely if that temperature is sustained or exceeded.

http://www.exploroz.com/Forum/Topic/104667/3ltr_BT50_Transmission_Hot.aspx?ky=&sn=&p=%2FForum%2FDefault.aspx%3Fpn%3D2

The problem with these new transmissions is high temperatures will melt the plastics in the insulation on the transmission solenoids and wiring, resulting in transmission failure.

Manufacturers use the minimal amount of oil in their designs, that they believe can satisfactorily perform the job. Too often, that amount of oil is inadequate, particularly when extended periods of towing or high temperatures (or both) are encountered.

Anything you can do that increases the oil capacity of the transmission, as well as increasing the heat dissipation from the oil, will help enormously with transmission life.

Many auto transmissions specify no oil changes for the life of the transmission. I personally believe 100,000km transmission oil changes are a good way to extend auto transmission life.

Hi iijmartin,
I have been monitoring trans temp with a Scangauge 2 on my 2012 DMax. The cooler I had fitted is large, approx 300mm x 300mm and has a thermostat controlled fan with an override switch in the cab. I can't give you temps before fitting the trans cooler as I did not have the Scangauge. My observations towing a one tonne camper trailer at speeds up to 105 kl/hr to Darwin and back via the Gibb River Rd are as follows. At a steady 100 k/hr on flat roads air temp around 30 degrees the trans temp is 55 to 60 degrees C. If I am doing slow work the temp starts sneaking up, I hit the fan switch at about 65 degrees and the temp starts to fall almost immediately. Time will tell how the trans life is effected, maybe it is running too cool?
Regards
Scooby

Hi Ian and Kathleen,

We have a 2012 Ford Ranger (3.2 litre auto), so same engine/transmission as the BT50.

We have just returned from a 5-month "big lap of Oz", where we travelled 22,000kms towing a 2.7 tonne caravan. Overall fuel consumption was 16 litres/100kms.

We fitted a ScanguageII before the trip, and used it to constantly monitor the engine water temperature, the auto transmission temperature and turbo boost. We tow in 4th gear sports mode, unless going downhill (5th sports mode), or going uphill (sports auto mode). Below are our observations of temperatures:

- not towing: water temperature in range 89 - 92, auto temperature in range 96 - 99
- towing: water temperature in range 89 - 94, auto temperature in range 99 - 104
- turbo boost towing never exceeded 20.

We have observed that if we tow in 5th sports mode, the auto temperature will rise to 104, and want to keep going upwards, while the water temperature will typically be at the lower end of the above temperature range. Changing back to 4th sports will result in the temperature dropping back into the above range. We will slow down as required (eg uphill) to keep the auto temperature at or below 104.

We have tried unsuccessfully with 4 Ford dealers and the Ford Customer Service to find out the safe upper temperature for the auto transmission temperature. The best we could get (from one dealer) was - "keep it below 110, and you should be right". Not very reassuring!!!

We have not been able to keep a definitive quotation to have an after-market transmission cooler fitted. The "ballpark estimates" have ranged from $900 to $1350. One auto transmission specialist said he would not be prepared to fit an aftermarket cooler, due to the way Ford has designed/fitted the standard heat exchanger (note - it is not a transmission cooler in the traditional sense).

So, where are we at? We will keep driving the way we have been until:

- we can get a definitive answer to the question of safe maximum auto temperature
- we can get information from a number of Ranger/BT50 owners who have successfully fitted an after-market cooler, and used it without problems for a goodly period of time
- we can get a more reasonable, definitive quotation to have an after-market cooler fitted.

By the way, we choose to tow in 4th sports mode, as the "general wisdom" is that it is not wise to tow (and particularly tow heavy loads) in an overdrive gear. 5th and 6th in the Ranger/BT50 are overdrive gears.

Cheers,

I'm guessing its the same as the 6speed Landcruiser - the TFT's drop once the torque converter locks. In the Landcruiser it locks more quickly in S5 or quicker again in S4. Maybe towing in S4 is what you need to do.
Also I think 107 degrees is nothing dramatic - mine gets to that just by driving the south east freeway out of Adelaide and not towing.

I stuffed my ZF gearbox at 120k after sand driving and towing with the stock cooler. The trouble is once you overheat the fluid the lifespan of the fluid is greatly reduced due to oxidisation. I would never buy a vehicle that had a 'sealed for life' gearbox for this reason.
Have a look at this chart that shows how quickly you can oxidise the fluid if you overheat the gearbox.
http://www.digi-panel.com/trannyoil.htm

I've since fitted a larger cooler and full synthetic fluid, so far so good!

Cheers
Mark

Sounds like you are all very worried about the tow capacity of your vehicles (autos) if the manufacturer say that the vehicle has a 3500Kg towing cspacity then if the trans has a problem it would be a warranty job. If you do not have trust in your vehicle then get reed of it and get a D.Max. Our has now done 43K in 13 months towing the camper (1400Kg) and around 6Ks towing the 2500K van and not one problem.