When is a Transmission cooler required?

[losh1971]

It needs to be run through the rad first. The rad warms the oil which is also required.

 

[Ginger Beer]

Read a few threads on here where people have said they failed. The odds are probably fairly slim TBH and you can probably negate it by changing the radiator say every 100,000kms.

Still the pedantic me doesn’t like built in points of failure. I removed (bypassed) the stupid throttle body coolant hoses on the missus Subaru Tribeca as it’s completely superfluous here in Australia. I would have removed the massive thick steel plates they put over the fuel injectors too but they were integral to the manifold setup. If I see a stupid piece of engineering I’ll always remove it or improve it where possible.

It was engineered in for reason, 100% of cars with slush boxes run this way, not because it is stupid, it is because the system was designed that way

Trans fluid optimal temp is somewhere around 80 - 100°c, over is bad, under isnt as bad but it not optimal

Trans fluid, like engine oil, is designed to run at a certain range, normal "unloaded" running with the fluid running through the cooler kerps the trans temps roughly around the optimal range

Leaning harder on the car and stalls heat up the trans more, adding a air to oil cooler inline will drop those temps to oprimal range

Speak to your local performance transmission specialist about, when I had my transmission built by Craigs Automatics I asked all about trans temps, their reply was to run a cooler in series with the radiator, log trans temps and see what happens

My stalled 4l60e gets ragged on with 900nm of torque and 380kwatw quite regularly and is loving life, the fluid is still nice and clean with no burnt fluid smell at all when it gets changed, typically trans temps are around 85-90°c, after a big hit they pop up to around 100-105°c, but stabilise pretty quickly

My trans fluid is changed in January every year

Opinions may vary

 

[J_D 2.0]

It was engineered in for reason, 100% of cars with slush boxes run this way, not because it is stupid, it is because the system was designed that way

Trans fluid optimal temp is somewhere around 80 - 100°c, over is bad, under isnt as bad but it not optimal

Trans fluid, like engine oil, is designed to run at a certain range, normal "unloaded" running with the fluid running through the cooler kerps the trans temps roughly around the optimal range

Leaning harder on the car and stalls heat up the trans more, adding a air to oil cooler inline will drop those temps to oprimal range

Speak to your local performance transmission specialist about, when I had my transmission built by Craigs Automatics I asked all about trans temps, their reply was to run a cooler in series with the radiator, log trans temps and see what happens

My stalled 4l60e gets ragged on with 900nm of torque and 380kwatw quite regularly and is loving life, the fluid is still nice and clean with no burnt fluid smell at all when it gets changed, typically trans temps are around 85-90°c, after a big hit they pop up to around 100-105°c, but stabilise pretty quickly

My trans fluid is changed in January every year

Opinions may vary

Well I wasn’t implying that it was stupid to run the trans cooler through the radiator, just that it’s a point of failure. The missus Tribeca on the other hand is stupid because they were all bought here to Australia without any of the “winterising“ for North American minus 30 degree winters removed from them.

It’s like bringing a polar bear here to live in the 40 degree outback and wondering why it dies from heat exhaustion. Had no end of problems on that car with brittle plugs on sensors, radiator end tank splitting from being brittle etc because the whole engine bay was covered in metal heat shielding and full plastic tray covering the whole underneath of the engine bay.

Basically it’s hermetically sealed to stop the heat escaping unless the car is physically moving because there’s no natural air movement (heat rising) through the engine bay. Needless to say I got rid of the plastic shield underneath the engine, got rid of the stupid beauty cover on the engine because we don’t need those things here in Oz.

 

[Fu Manchu]

 

[J_D 2.0]

So you’d actually be better off fitting a bigger radiator (more cores for overall cooling capacity) than fitting any automatic transmission cooler. Even just fitting a lower temp thermostat would be more desirable (probably not recommended though).

The extra transmission cooler in the airstream won’t cool as effectively as just lowering the radiator coolant temp by a few degrees and letting the trans cooler in the radiator do it’s thing.

 

[Ginger Beer]

So you’d actually be better off fitting a bigger radiator (more cores for overall cooling capacity) than fitting any automatic transmission cooler. Even just fitting a lower temp thermostat would be more desirable (probably not recommended though).

The extra transmission cooler in the airstream won’t cool as effectively as just lowering the radiator coolant temp by a few degrees and letting the trans cooler in the radiator do it’s thing.

Yeap, sort of, nope, I don't think it's that easy

The problem then would be engineering, design and cost

Air to oil cooler in line with the radiator is fairly cheap to help lower trans fluid temps to their happy place, yoy don't need to block the radiator for a air to oil cooler to work

I have no idea of the engineering involved to do the same by re-engineering the cars radiator, or the cost, I imagine it would be bespoke for each model, like nearly every other radiator out there

I'm a big fan of old John, but he is pretty much not a fan of modifying cars

Opinions may vary

 

[Immortality]

Holden fitted an external transmission cooler as part of the tow package, from VT onward some models had a internal transmission cooler in each radiator tank and still fitted the external cooler as part of the tow package where they could have just fitted a larger radiator? One has to wonder why.

 

[Immortality]

He makes some salient points but this video seems to be about larger 4x4/double cab ute type vehicles.

The original BT50 was having engine overheating issues before the transmission overheated so he's correct, fix the engine cooling... He makes a very good point about all the **** you see on the front of the double cab utes with all the crap bolted in front of the radiator (big winch and flood lights).

He's correct, trans fluid does have an optimal operating temp, so much so that most late model cars now have thermostat fittings fitted into the trans cooler circuit to ensure they don't run too cold.

He is correct, water is a better medium for heat transfer, his big failure in his example is ignoring surface area which is quiet critical to cooling (how does your radiator cool the water?). If you look at a external trans cooler it has a lot of surface area to allow heat convection to occur and compare this to the surface area of the internal trans cooler inside the radiator tank.

We will completely ignore that your radiator is a water to air cooler....

It makes me laugh when you see people fitting fancy coolers under cars in places with little to no natural airflow and then fit a thermofan to said cooler. Put the cooler where it's going to get natural airflow.

 

[Fu Manchu]

I watched all of that. I’ve read heaps of threads on them. Then I’m going to do what I want and install a good size external cooler.

 

[Immortality]

Agreed, I stand by my original post in this thread.

My recommendation would change if you lived in Antarctica....