hey all. done a search but cant find the info i need.

is there much benefit fitting a external trans cooler and completely bypassing the factory one?
if so what sized one would be the best to go for?

the car in question is my te exec 3.0 v6 4spd auto. which i'm fitting a th auto to it (3.5 litre 4spd auto).
a mate suggested that i do. but i'd have no idea on what size would be appropriate.


the te has a towbar. but i use it infrequently as i dont like towing with a fwd when its aheavy load. hence why i have the falcon
however i do alot of stop start driving\city driving

In my opinion, auto trans coolers are a must have in any magna. Most of the members here serious about their Magnas/Veradas & 380s with an auto trans will have an inline cooler fitted. You'll gain slightly better shift quality, longer tranny service life with the fluid in better condition between changes etc..

Regardless of the type of transmission cooler you get, I strongly recommend you to fit the cooler in-line as opposed to a bypass configuration. Something to do with temperature regulation of the transmission fluid which is critical for longiveity & minimal wear & tear.
Also, Magnas have an 8mm diameter (or 5/16" imperial equivalent) for transmission hoses & fittings.

I have fitted a derale 7000 series fin type cooler which is quite large, fitted in-line, passenger side off centre behind the front grille, arranged verticaly with the hose outlets facing down.
Web link: http://www.autobarn.com.au/derale-7000-series-tube-and-fin-transmission-coolers-13103

the car in question is my te exec 3.0 v6 4spd auto. which i'm fitting a th auto to it (3.5 litre 4spd auto).
a mate suggested that i do. but i'd have no idea on what size would be appropriate.


Won't the final drive and gearing be too high for a 3.0L as it has less torque?

In my opinion, auto trans coolers are a must have in any magna. Most of the members here serious about their Magnas/Veradas & 380s with an auto trans will have an inline cooler fitted. You'll gain slightly better shift quality, longer tranny service life with the fluid in better condition between changes etc..

Regardless of the type of transmission cooler you get, I strongly recommend you to fit the cooler in-line as opposed to a bypass configuration. Something to do with temperature regulation of the transmission fluid which is critical for longiveity & minimal wear & tear.
Also, Magnas have an 8mm diameter (or 5/16" imperial equivalent) for transmission hoses & fittings.

I have fitted a derale 7000 series fin type cooler which is quite large, fitted in-line, passenger side off centre behind the front grille, arranged verticaly with the hose outlets facing down.
Web link: http://www.autobarn.com.au/derale-7000-series-tube-and-fin-transmission-coolers-13103

Couple of dumb questions...

1) Here in Tas, it has been known to get quite cold (about minus 5 at my place and the places i drive). Do you believe a thermostat is a good idea, or will the oil temp whilst driving be too high for it to suffer a major temp loss across the cooler?(probably a Mal question!)
2) If a thermostat was installed (in line) wouldnt it cause a huge pressure increase behind it, and give you split lines or busted joints (or do you have swaged fittings rather than good old clamp and flex lines)
3) Can you pls upload (or pm) me some pics of the install
4) Does anyone know (Mal again ??) the "normal" range of tranny fluid operating temp?
5) The big one....does anyone know the temperature drop across an oil cooler under "normal" driving conditions? (Probably another Mal question)
6) Which is easier....installing a genuine mitsi cooler, or aftermarket? (I would reckon aftermarket, as you can put it wherever you want, rather than where mitsi tells you) (Makita drill, here i come!)
7) Anyone know what the working pressure of the cooler lines would be?...As Im thinking swaged fittings from Pirtek or somewhere like that would be the easiest option, as you could have them made to length and the correct screw in fittings at each end and simply screw into old cooler lines...any comments
8) Thanks to all..:bowdown:


(Sorry, its the engineer in me)

FWIW, I made my own auxilliary cooling system using two 2nd Gen transmission oil coolers. Together, those cost $50 from a wrecker. I added a bypass thermostat for another $50 or so. Total cost, including bracket fabrication, hoses & clamps was around $125. The bypass thermostat shuts off all external cooling until the fluid heats up to at least normal operating temperature - they're designed for use in cold regions (e.g. Canada). For details, see: http://www.4shared.com/office/Bsu_uonN/TW_VR-X_AWD_Transmission_Oil_C.html. So far, I've done about 85,000km with the coolers, including 27,000km towing a caravan all around Australia. But I also live in Canberra, where winters are typically rather colder than where most people live in Tasmania.

My auxilliary coolers are configured so that the fluid goes through them before going through the factory one that's built into the radiator. That way, if the fluid gets over-cooled by the external coolers, the radiator one will warm it up again and, conversely, if it's still not cool enough, will get a little more cooling. Having taken careful note of how long it takes the transmission to warm up (by watching how long it takes for the tacho:road speed relationship to match normal conditions) it appears the fluid now warms up more quickly this way - especially useful in Canberra's winters where the car might be starting in sub-zero temperatures.

The fluid pressures aren't very high, and ordinary hose clamps will do just fine. That's what Mitsubishi uses, after all. Thermostats don't impact the pressure - they have a bypass valve that returns the fluid direct to the transmission until the fluid warms up. Without the bypass valve, there'd never be any fluid flow through them, so they'd never get hot enough to open and you'd cook the transmission real quick.

Thanks Macropod for answering jisniow's questions.

In my opinion, auto trans coolers are a must have in any magna. Most of the members here serious about their Magnas/Veradas & 380s with an auto trans will have an inline cooler fitted. You'll gain slightly better shift quality, longer tranny service life with the fluid in better condition between changes etc..

Regardless of the type of transmission cooler you get, I strongly recommend you to fit the cooler in-line as opposed to a bypass configuration. Something to do with temperature regulation of the transmission fluid which is critical for longiveity & minimal wear & tear.
Also, Magnas have an 8mm diameter (or 5/16" imperial equivalent) for transmission hoses & fittings.

I have fitted a derale 7000 series fin type cooler which is quite large, fitted in-line, passenger side off centre behind the front grille, arranged verticaly with the hose outlets facing down.
Web link: http://www.autobarn.com.au/derale-7000-series-tube-and-fin-transmission-coolers-13103
yeah i was surprised to find it didnt have a external one already. as with the falcons i've had with factory towbars have had one.

true. running bypass may upset the warm up of the oil etc.

ah cool i'd replaced 2 of my hoses when i replaced the radiator. but couldnt remember the size.

what did that set you back if you remember and how'd you route the hoses to the cooler? as i'm guessing you went under the radiator between the rad support rad\condensor?

Won't the final drive and gearing be too high for a 3.0L as it has less torque?
i don't think it will be as both sat at simular rev's on the freeway etc.
yes the 3.5 was quicker off the mark. but if i pulled the mixer ring off the 3.0 it wouldn't be much difference in it in my opinion.
also the 3.5 needs work done to it where the 3.0 doesn't

only one way to find out i suppose and see how i go.
the th i got for parts was too good a deal to pass up. and i couldnt find a te for parts with a good gearbox at the time.

Got my mechanic to do the install he said it took around 2 hours. Derale 7000 series kit cost me about $120 from autobarn. You could probably buy them cheaper on line, but be aware that there are sellers that sell the coolers only, where no additional hoses or fitting accesories are provided, so don't be duped by cheap price.
I also bought another 1 metre of additional hose & an external in line transmission filter which cost me an additional $ 35 or so. I'll see if I can take some pics later and post them up.

Since the Derale 7000 series doesn't include a bypass thermostat, you may need one of those too (even in Qld) - especially if the cooler either bypasses or follows the stock one.

If you set it up so the fluid flows to the aux cooler first, then through the radiator and back to the transmission you won't have any problems with the fluid being too cold. I live in Melbourne and even in the middle of winter there are no problems. Then in the 40C heat it is still fine, esp. with the air-con running with the fans on.

The bypass thermostat is a good idea. If I were to use one I would set it up so that the fluid goes to the radiator first then the aux cooler since you don't have to worry about it being too cold. This would keep the fluid that little bit cooler and give it a longer life.

Got my mechanic to do the install he said it took around 2 hours. Derale 7000 series kit cost me about $120 from autobarn. You could probably buy them cheaper on line, but be aware that there are sellers that sell the coolers only, where no additional hoses or fitting accesories are provided, so don't be duped by cheap price.
I also bought another 1 metre of additional hose & an external in line transmission filter which cost me an additional $ 35 or so. I'll see if I can take some pics later and post them up.
ah ok..
sweet. thats a fair price considering.
true. i typically make sure on what kits include anyways. thanks for the heads up though

some pictures would be great. even if they sorta show how the hoses run i'd be stoaked

Since the Derale 7000 series doesn't include a bypass thermostat, you may need one of those too (even in Qld) - especially if the cooler either bypasses or follows the stock one.

i'll see how i go first.. as i may not have problems with warmup in werribee (vic)

I really dont think under heating of the fluid will ever be a real issue, fluid comes under large pressure from the pump, pressure = heat, especially that much pressure, correct me if im wrong working pressure out of the pump equals to 100-300psi or so, it heats it up instantly and gets very hot. Unfortunately its impossible to cool fluid as it comes out of the pump (imagine the stress on rubber hoses and clamps) so external cooler is not actually cooling the hottest portion of the fluid in the transmission. That said its still a must have imo.

I think you'll find the cooling side of things doesn't run at anything like 300psi, or even 100psi. There's no need for high pressure there; what's required is high flow. And yes, it's quite possible to overcool a transmission (including cooling it before it's reached normal operating temperature) - that's why bypass thermostats exist!

I think you'll find the cooling side of things doesn't run at anything like 300psi, or even 100psi. There's no need for high pressure there; what's required is high flow. And yes, it's quite possible to overcool a transmission (including cooling it before it's reached normal operating temperature) - that's why bypass thermostats exist!

Yes of course thats why i said that you cant cool straight from pump due to high pressures, pressure is greatly reduced when it runs through cooler. My point is that the the thermostat you have only reads temperature right next to the cooler when is not the actually the hottest portion of the fluid (which is right after the pump).

My point is that the the thermostat you have only reads temperature right next to the cooler.
You are completely wrong about that. Check out the doco in the link I posted. The bypass thermostat measures the fluid temp immediately it leaves the transmission and that's nowhere near the coolers. It would be difficult to position it any closer to the transmission than where I have it.

Geez, regardless, its not measuring it after the pump, where it is the hottest. or i am completely wrong about that too?

Doesn't the thermostat just route the fluid back to the transmission if it is too cold? Then when it warms up it starts to circulate it through the cooling circuit. Seeing as it has a constant flow through it, it can meassure the temperature.

Would be wise to run the fluid through the radiator first so it will warm up quicker. Otherwise the fluid will take longer to heat up as it has to rely only on the heat generated by the transmission alone. Doing this will add extra complexity to the system when it would be best kept simple.

Another thought. The transmission computer will not lock the torque converter untill the fluid is warm. This should ensure it will get up to temp by creating extra heat, at the expense of fuel economy.

Geez, regardless, its not measuring it after the pump, where it is the hottest.
Of course it's after the pump. How else do you suppose the fluid gets from the transmission to the cooling system? And what do you suppose the temperature difference is between it and the pump??

or i am completely wrong about that too?
In a word, yes. The fluid gets hottest going through the torque converter.

Would be wise to run the fluid through the radiator first so it will warm up quicker. Otherwise the fluid will take longer to heat up as it has to rely only on the heat generated by the transmission alone.
We've been through this before - a cold radiator with no bypass slows down the rate at which the fluid reaches the correct operating temperature. The heat generated within the transmission is much greater than anything it gets back from the radiator. With the bypass, it heats up faster than without it. That's why they're used in places with severe winters, like Nth US & Canada. Indeed, once the trans fluid has reached its correct operating temperature and the bypass opens, it helps warm up the radiator under such extreme conditions.

Of course it's after the pump. How else do you suppose the fluid gets from the transmission to the cooling system? And what do you suppose the temperature difference is between it and the pump??

In a word, yes. The fluid gets hottest going through the torque converter.

i actually replied to this nonsense. But then got rid of it, you know what you are right everybody should have thermostats, they save transmissions from overcooling.