Do I need a transmission cooler

[JethroT]

Hi guys,

I've been towing a 1400Kg Goldstream with a 2003 Prado 3Ltd diesel for the last 12 months without any obvious concerns, however with a view to longevity I wonder whether I need a transmission cooler coming into the warmer months.

Does anyone have any experience good or bad with transmission coolers.

[TheOtherLeft]

Do you have an auto or manual transmission?

Does your transmission fluid look or smell burnt? Unburnt fluid is red in colour, burnt or even old is blackish. Plus burnt fluid smells very different to unburnt fluid.

Even if not a cooler is a very good idea if towing a lot.

It also matters where you mount the cooler. I was told by Natrad that mounting a cooler high up in front of the radiator could be detrimental to the engine as the radiator can't cool properly due to the now hotter air (from the cooler) going to the hot part (top section) of the radiator. You could mount the cooler down lower but then you may have clearance problems if you go through mud/sand.

[JethroT]

Thanks,

It's an auto and I haven't noticed any issues with the fluid when I've checked the levels, however I'll go and give it a better inspection now.

Regards

[Bird]

If your running an auto, it is a great idea, and will only do you good provided you buy a good one and its protected well.

[Swogjb]

I recently had an oil cooler fitted to the Hilux.
Before  I fitted the cooler when towing our Jayco  if I pushed her a bit hard the trans light would come on,  as soon as I backed off the light would go out.
When the trans was getting hot it would change back a gear all the time, almost like the trans didn't know what gear to be in.
I recently tested the cooler out, towing into a strong northerly wind for about 550k upto Mildura.
The transmission worked much better than before, not dropping back a gear all the time and no sign of the trans light.
 
Glenn

[sablesoft]

I recently had an oil cooler fitted to the Hilux.
Before  I fitted the cooler when towing our Jayco  if I pushed her a bit hard the trans light would come on,  as soon as I backed off the light would go out.
When the trans was getting hot it would change back a gear all the time, almost like the trans didn't know what gear to be in.
I recently tested the cooler out, towing into a strong northerly wind for about 550k upto Mildura.
The transmission worked much better than before, not dropping back a gear all the time and no sign of the trans light.
 
Glenn

Hi Glenn,

What Oil Cooler did you use ?

Ray

[gadgetman]

I tow a fair bit and haven't had issues with this although if the roads are hilly I tend to keep the gears in 4th - not overdrive, to avoid the gearbox hunting for the right gear.
Rob

[jtraf]

I have a GQ Turbo deisel auto and for the sake of peace of mind I fitted a B&M 70297.  It is a largish cooler with built in temp switch that will turn in the built on thermo when oil temp reaches 80deg celcius.

I also have a oil temp guage onto the auto output line and the worst I have seen while towing has been 80deg at the output but it was never hot enough by the time it got to the auto cooler to turn on the thermo so I know that the auto is always cool.

At around the $350 mark it is not cheap but what would an auto failure cost...

HTH

James

[Swogjb]

Hi Glenn,

What Oil Cooler did you use ?

Ray

Hi Ray,
My cooler is a Hayden Rapid Cool.
http://www.haydenauto.com/Featured%20Products-Transmission%20and%20Engine%20Oil%20Coolers/Content.aspx
 

[Bird]

At around the $350 mark it is not cheap but what would an auto failure cost...

bout 4000.....

[D4D]

I plan to do this one day, the problem with the Prado is working out where to fit one as mounting it in front of the radiator is not really possible.

For an authoritative answer try Rodney http://www.automatictransmission.com.au/

[Bird]

I found the large PWR ones flow really nicely

[WilSurf]

I have added an auto cooler to mine and the temp is definately lower.
The Surf has the transmision fluid running through the radiator to cool down, maybe the Prado has the same.
I have the Craig Davis V8 cooler installed in serie and an additional digital temperature gauge. On our trip towing the KK it showed under 80 degrees while before it was high 90.

[D4D]

The Surf has the transmision fluid running through the radiator to cool down, maybe the Prado has the same.

Yes

[Swogjb]

Yes

Hilux is the same

[Bird]

The Surf has the transmision fluid running through the radiator to cool down, maybe the Prado has the same.

it can be a good idea to bypass the radiator... many do this while they are at it, then you dont heat the water and vice versa when you don't need to..

awill4x4 had some top data on this on outers, patrol, and eoz forums..

[WilSurf]

Some do by-pass and found that it doesn't work properly.
The transmission fluid is also used to heat up the engine to working temp when the ambient temp is cold.

[dazzler]

The Surf has the transmision fluid running through the radiator to cool down, maybe the Prado has the same.

Which is one of the main reasons that the surfs often overheated.  The trans cooler actually blocks the lower radiator outlet on the surf but doesn't on the 4Runner.  You can see the cooler if you pull the radiator.

[dazzler]

Hi guys,

I've been towing a 1400Kg Goldstream with a 2003 Prado 3Ltd diesel for the last 12 months without any obvious concerns, however with a view to longevity I wonder whether I need a transmission cooler coming into the warmer months.

Does anyone have any experience good or bad with transmission coolers.

There is an old off road racers saying (probably stolen from someone else) that goes "parts left out cost nothing and create no service problems"

Sure fitting a transmission cooler will cool the trans oil.  But is cool oil what you want?  Its designed to operate at a certain temperature and given the fact that most mechanical wear on components is when cold you may actually be doing more harm than good in the long run.  The trans will take a long time (if ever) to reach the correct operating temperature and would probably only ever get there when you are really flogging it.

The prado has an AT overheat light so I would go off that.  If it comes on then back off.  I am aware the D4D models do this a fair bit when pushing hard in sand but they dont crap themselves.

So my 2c is leave it stock.

cheers

[D4D]

The prado has an AT overheat light so I would go off that.  If it comes on then back off.  I am aware the D4D models do this a fair bit when pushing hard in sand but they dont crap themselves.

The 150s are known for this

[Swogjb]

I was talking to a transmission specialist and in his opinion all vehicles that are towing on a regular basis should have a cooler fitted.
The difference that it has made to the Hilux in really noticeable.
Before the cooler was fitted you could tell when the oil was starting to get hot before the light would come on. Trans would keep dropping back a gear all the time.
Toyota dealer reckons they fixed the problem by reflashing the computer , but that made bugger all difference.
IMO transmission oil coolers are worth the money.
 

[RebsWA]

I had an 06 Hilux D4D auto and have towed my Jayco Eagle from Albany WA to Darwin and a few places in between over the last few years. Had some pretty hot weather in all this and had to hot foot it from Kununurra to Perth once for a family emergency. Never had an issue with the auto trans and never seen the temp light on.
Last year I traded it on another new Hilux which I intend to keep longer than the usual 4 years, so I thought I would fit a cooler. After some research I decided to fit an oil thermostat with the cooler so the vehicle operates as Mr Toyota intended, but should the fluid get above the NOT (normal operating temperature) when towing, the fluid is directed thru the cooler. Seemed like reasonable logic to me.
Well after 8,000 kms (but with little towing) I have yet to feel the cooler get hot. It gets tepid as a small volume of fluid is recirculated thru it constantly but it is obvious the thermostat has yet to open.
So that tells a story.
I had also installed a transmission digital temperature gauge prior to fitting the cooler so I could record the before and after effect the cooler had. Needless to say I have noticed no change. One thing I would conclude is that without the thermostat the transmission would probably never get to NOT in cold weather. If that is good or bad I am not sure as I am not a auto trans mechanic but when I first floated the intention to fit a cooler to my Toyota service manager he baulked at the transmission running below NOT.
Anyway that's my 2 bob's worth on the subject and I am satisfied the trans is operating normally but has the provision of an extra cooler should the need arise.

[Black Diamond]

Heat is the biggest killer and an aftermarket trans cooler is money well spent in any application especially towing. Don't think DO as a famous coach once said!

[Bird]

Heat is the biggest killer and an aftermarket trans cooler is money well spent

x eleventy

[albany_nomads]

Which is one of the main reasons that the surfs often overheated.  The trans cooler actually blocks the lower radiator outlet on the surf but doesn't on the 4Runner.  You can see the cooler if you pull the radiator.

Correct on the Surfs,.... the transmission cooler  is a very large tube in the bottom tank of the radiator that also restricts flow of engine coolant..this is great as Will pointed out if you are in JAPAN wheres its cold and the transmission can be used to heat the engine coolant but in Australia you don't want to heat the motor up with the tranny fluid as such the 4 Runners have a more appropriate designed transmission cooler in the Radiator without restricting flow of the engine coolant.
If you are going to bypass the radiator all together and purely depend on a external transmission cooler that's fine but make it large and remember that it needs to be positioned to get air flow when the vehicle isn't moving as well
As such if its not in-line with your engine fan think about an axillary fan..or keep moving  ..Whilst I'm a great fan of Autos, and think in some ways make better 4x4's also keep in mind as some one pointed out Temperature is the biggest killers of Auto Trannys..kind regards John