Transmission cooler for automatic

Submitted: Thursday, Aug 03, 2023 at 12:27
ThreadID: 146059 Views:2869 Replies:7 FollowUps:13
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I've purchased a new Dmax ute and I'm going to be towing a Van that weighs approximately 2.7 tonnes has anyone else had issues with the transmission getting to hot or failing
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Reply By: RMD - Thursday, Aug 03, 2023 at 12:54

Thursday, Aug 03, 2023 at 12:54
G'day Craig.
Although the theoretical capacity is 3.5t, that is the max and probably 75% of that is the realistic value. It will move that weight along a road but isn't practical for all situations.
Any weight increase creates more temp within the torque converter and many times, except extremely favourable conditions, the auto will often be operating NOT in LOCKUP mode and so the TC is developing additional heat into the fluid. That will of course elevate the auto fluid temperature. IUA will probably not endorse the fitting of a trans cooler, even though on a hot day, up hill, with a tail wind and towing 2.7T the auto trans will heat up significantly.
Any additional fluid heat is delivered straight to the radiator water heat exchanger, so any additional heat stresses the radiators ability to cool not only the engine but the trans as well.
I would definitely fit one and even have a temp sensor controlled OR manual switched fan assisted cooling airflow for the trans cooler. A great addition is a scan gauge or similar device plugged into the OBD port to read and display auto fluid temp. That way you can monitor the auto temp, sort of. Keep in mind, the temp indicated is ONLY the fluid inside the auto trans and NOT the hotter exit temp of the fluid which is sent to the radiator heat exchanger. Any heat dissipated by a trans cooler is heat which is NOT added to the water cooling system, ONLY IF the trans cooler is placed in the exit HOTTEST line from the auto to the radiator. Cooler in the coolest line still ADDS auto fluid heat to the radiator first. Which is Not my idea of cooling if ever in hot climates or harsh conditions are experienced.
If your vehicle ever gets to warning you or goes into limp mode, the auto has been very hot.
Aisin autos are usually very good, so you should not have problems if not abused by negative usage or heat. Heat will kill any auto.
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Follow Up By: Craig S20 - Thursday, Aug 03, 2023 at 13:21

Thursday, Aug 03, 2023 at 13:21
Thank you RMD now to find one of suitable choice
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Reply By: Athol W1 - Thursday, Aug 03, 2023 at 14:01

Thursday, Aug 03, 2023 at 14:01
craig.

The current Dmax and BT50 are essentially the same vehicle, and I have the BT50 version.

These vehicles are NOT fitted with a heat exchanger within the engine radiator, but WITH a heat exchanger that is located beside the Bell Housing, and is cooled/heated by controlled temp engine coolant (ie coolant circulating from the top of the engine (hot coolant) and returning to water pump). This system ensures that the transmission WILL warm up regardless of ambient temperature, whereas the old in radiator system could keep transmission temps very low in freezing ambient temps.

I operated my vehicle for several weeks paying close attention of both engine and transmission temps under a variety of operating conditions, but not towing, and the normal operating temp for the engine is 87 deg. with the transmission always just a few degrees either side of that (measured using Scangauge 11)

I then fitted a cooler before any towing duties and still find those temps are maintained, even when put to the test towing 3t up Cunninghams Gap between Aratula and Warwick SE Qld in February, a 9km climb speed restricted to 60 and 80kph.

It has been fitted to the hot line out of the transmission (which just happens to be the easiest line to access at the heat exchanger) and returns via the heat exchanger to the transmission. This system has NOT seen any appreciable drop in transmission temp, BUT it sees little to no increase in either engine or transmission temps when towing and working hard.

I mentioned this to my Dealer's Service Manager and his reply was "that it is a good thing and can have no adverse effect on the transmission".

It would appear to me that the trend by vehicle manufacturers is to now control the 'warm up' of their transmissions, whilst also preventing them getting too hot. The addition of a cooler as I have it fitted still causes the transmission to attain the manufacturer's desired operating temperature within a few degrees, whilst at the same time dissipating, or taking care of, the additional heat load from the entire cooling system when being asked to work hard.

Manufacturers have gone to low viscosity oils so that it 'squeezes out' from the clutch packs, and they are also now ensuring that the transmission warms sufficiently to also assist that oil to escape the clutch packs to reduce slippage at the gear change points, but it is also good to ensure that the transmission (or any machinery) does not overheat.

Hope this is of assistance.
Athol
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Follow Up By: Craig S20 - Thursday, Aug 03, 2023 at 14:09

Thursday, Aug 03, 2023 at 14:09
Thanks Athol may I ask what system you installed
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Follow Up By: Athol W1 - Thursday, Aug 03, 2023 at 14:21

Thursday, Aug 03, 2023 at 14:21
Craig

I went to Repco and got the largest cooler that they had in stock (which happened to be made in Yatala by the mob that are making radiators for the Supercars), made my own brackets and purchased sufficient Auto Cooler Hose (6 metre, but had some left over, would rather have too much than be 100mm short) to reach the heat exchanger.

Regards
Athol
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Reply By: Kazza055 - Thursday, Aug 03, 2023 at 14:30

Thursday, Aug 03, 2023 at 14:30
Craig, I have been towing our 2,500kg van since 2014 and have towed about 50,000km.

I fitted a Scangauge11 back in 2015 and have seen the ATF climb to 115c on a few occasions, the last time was towing between Kalbarri and Carnarvon with an outside temperature of 44c and a strong tail wind so not much air flowing through the radiator. It got hot enough for the ECU to shut down the air-conditioning. Within weeks of getting home I finally had another cooler fitted by my dealer, Major Motors in Bibra Lake WA.

Pre install I was seeing the ATF temp about 10c higher than the coolant, it now is normally sitting about 10c below the coolant so has dropped the temperature by 20c.

We recently did a 10,000k trip and never had the ATF reach as high as the coolant at all.

I have been lucky with Major Motors as they have never faultered with warranty, they suggested I do a GVM upgrade pre purchase and when I asked for the cooler, they just did it without any questions or claims of it voiding my warranty.

If you are having problems with your dealer, it's time to find one that will support you.
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Follow Up By: Craig S20 - Thursday, Aug 03, 2023 at 14:58

Thursday, Aug 03, 2023 at 14:58
Thanks Kazza055 what brand if you don't mind me asking..
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Follow Up By: Kazza055 - Thursday, Aug 03, 2023 at 15:04

Thursday, Aug 03, 2023 at 15:04
Sorry but don't know as Major Motors supplied and fitted it. If you ask me, any reputable brand should do the job.

All I know is it works very well.
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Reply By: tonysmc - Friday, Aug 04, 2023 at 09:04

Friday, Aug 04, 2023 at 09:04
Hello Craig, because I tow, a transmission cooler is the very first accessory I purchase for my car. That and a scangauge. I wouldn’t be without one as they make a huge difference. My car, Hilux, transmission normally runs about 20 degrees cooler than car and with heavy towing only gets to about 90. In your case, being a new car, you would have to make double sure fitting one does not void any warranties?
As for fitting, (while others won’t agree) it should be on the return line after the car radiator and the best and most efficient and effective orientation to mount a cooler, is flow into the cooler at the bottom and out at the top. Some kits you buy are orientated different and I highly recommend rotating them to get the best performance.
I could give you a number of links that explain the reasoning of all this, however at the moment I can’t get links to work, but I’m sure I be adding some long links later to justify myself. lol. Tony
AnswerID: 644222

Follow Up By: Craig S20 - Friday, Aug 04, 2023 at 09:11

Friday, Aug 04, 2023 at 09:11
Thank you Tony look forward to reading your links
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Follow Up By: RMD - Friday, Aug 04, 2023 at 15:47

Friday, Aug 04, 2023 at 15:47
G'day Tonysmc,
I am interested why the cooler should be in the return line to the auto. As you are aware I regard fitting in the hottest line gets rid of the most heat possible and vastly lessens heat loading into the engine water for thermal safety, ie, before vehicle system is encountered. But, interested in why the coldest line may be preferable . Providing a reason why, helps an owner to decide.

Because the hot fluid going into a cooler isn't there long, how does it matter top or bottom for entry, if the cooler is in airflow from a fan or frontal forced airflow? Is there a quantifiable difference?
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Follow Up By: tonysmc - Friday, Aug 04, 2023 at 20:17

Friday, Aug 04, 2023 at 20:17
Hi RMD, yes I have found the before or after the radiator something discussed in many forums. If you look at most installation instructions, they advocate installing it on the return line. The Davies Craig website states “provides maximum cooling by returning the coolest fluid to the automatic transmission.”. Google “transmission cooler installation diagram” or images or “transmission cooler installation instructions” and they’ll be saying to put the cooler on the return line. My thinking (whether right or wrong) is a cooler is only going to cool, whereas the radiator may cool or heat the trans oil depending on what temp each is at. So, by going through the radiator after the cooler you can lose a little of the cooling affect. I hope that makes some sense, I’m trying to keep this short.
Now as for me being a strong advocate of entry at the bottom and exit at the top, this is all about preventing airlocks. Basically, getting air pockets trapped inside. Many coolers are installed with entry and exit on the bottom and I can guarantee that although they will still work they aren’t working as efficiently as they could because there will be air trapped up top. Look at any radiator system and they will always have an outlet or somewhere to bleed off air at the top. By coming in at the bottom and out the top, all the air will be pushed to the top evenly across the radiator as it fills, leaving no air pockets. I’ll try and link a couple of videos which may explain or show it better. First one is in reference to transmission coolers and the second video is just about airlocks/air restriction in general plumbing. (probably best starting at the 5min mark on the second vid) Apologies if the short “link” doesn’t work, I think my new virus protection may block it somehow?

https://www.youtube.com/watch?v=-0sit67SwYc

https://www.youtube.com/watch?v=zdkp9N3qfkI



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Follow Up By: RMD - Saturday, Aug 05, 2023 at 09:14

Saturday, Aug 05, 2023 at 09:14
G'day Tony.
Why dump hotter than boiling fluid into a radiator system which is already near boiling and has practically no reserve of cooling capacity left. Disaster approaching?
Fitting in the coldest line means; when the engine is near it's max output, ie, towing and the day is hot, the thermostat will most likely be fully OPEN but all is operating near to absolute MAX. If at or near that situation you are ALSO adding auto fluid heat at 120c + (auto working hard) to the heat exchanger/bottom of radiator, the system can suddenly have a thermal runaway and cause damage. The idea of fitting a cooler is because the water system is going to get near to or over it's ability to cool the engine AND auto. Heat dissipation is best when there is maximum difference between the ambient and the heat source, ie, air 35C to 40C day, and water near boiling point. Auto fluid is already more than 100C. So if you want to get rid of the most heat quantity then hottest line is best. That is after all, what we fit a cooler to achieve.
Yes it may over cool a little on freezing days if auto not working much. How many of those do we need to cater for? If in cold freeezing areas, cover the cooler in that situation or have a fancy temp regulated system.

Any degradation in cooling system performance ability instantly makes things worse. ie, blocked radiator fins/tubes and therefore system less than OE capable after a while. That exacerbates the original situation.

If a trans line suddenly came off, the auto would be empty in about 15 to 20 seconds maybe less at higher revs. The rate of flow with HOT fluid is high and is a positive pressure., Coolers are generally tube/fin designs, Flow rate will expel any air in seconds, once expelled how does more get in there? Air locks won' t happen. While your engine is running, even at idle speed, suddenly cut an auto hose and see the rate of flow. Solid hose flow, self flushing! How much air is retained in your garden hose when the tap is ON? Spit spit full flow with mine!
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Follow Up By: Member - LeighW - Saturday, Aug 05, 2023 at 10:30

Saturday, Aug 05, 2023 at 10:30
One would hope that a well designed cooling system would under normal operating conditions would always have some reserve cooling capacity left! I remember many moons ago when the thermostate on my Celica jammed opened one hot summer night while travelling from Geelong to Melbourne. I pulled over for some reason and when I started to move off the car started miss firing and carry on, it was then I looked at the temperature gauge and seen it was on cold. Didn't matter what speed I did I couldn't get the motor to warm to the point where the gauge would move off cold or get the automatic coke would turn off!

Under normal operating coditions the bottom of the radiator where the trans cooler usually lives should be relatively cool which is why the car manufactures place the trans cooler there, if its border line to boiling then one would have to say it is a poorly designed cooling system.

On my KIA sportage the factory designed trans cooling system runs through the bottom of the radiator and then through an air oil cooler back to the transmissiom. When I fitted the cooler to my Prados transmission Craig Davis indicated to fit cooler afer the factory transmission cooler, for curiuosity I did a search of the net and all the transmission cooler manufactures I could find either indicated to fit their units after the factory cooler or that it could be fitted either before or after but all recommend fitting after. One woud also have to wonder looking at the size of the transmission cooler compared to the radiator for example who much cooling aid it would be in lowering radiator temperatures.

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Follow Up By: tonysmc - Saturday, Aug 05, 2023 at 10:49

Saturday, Aug 05, 2023 at 10:49
"Hotter than boiling"? My transmission runs around 20 degrees lower than the car in normal driving. When towing it runs about the same temp (sometimes a few degrees over) but it NEVER gets over 100 degrees since fitting a cooler. If a car is running at about 84-90 it will have very little cooling effect anyhow. The larger companies are all saying cooler AFTER the radiator as it cools the transmission better which is what we are trying to do. If your transmission is getting to 120+ something is not right. To me, if you are going to fit one, there is no extra work in fitting it for the side orientation of the outlets, so why wouldn't you do it that way to eliminate any chance of trapped air whether you believe air gets trapped or not. I've put it out there what I think works the best, the great thing about forums is people can read differing opinions and come to there own conclusions. I'm not going to say anymore on this subject, but I might start another post about how to get my "links" to work! Here's one more from people who make and sell transmission coolers.
https://static.summitracing.com/global/images/instructions/bmm-bm_cooler_techdoc.pdf
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Follow Up By: Kazza055 - Saturday, Aug 05, 2023 at 16:09

Saturday, Aug 05, 2023 at 16:09
Not an expert on this but my thinking is if it goes into the radiator first and then through the cooler, it is going to always be cooler that the radiator.

Running it the other way around will the the temperature being the same as the radiator.

I have not looked at how mine is plumber but all I know is the ATF is usually 10c lower than the coolant so to me that is good.

Before fitting mine I would see the ATF at 10-20c hotter than the coolant so it definitely helps keep it cooler.
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Reply By: qldcamper - Tuesday, Aug 08, 2023 at 06:47

Tuesday, Aug 08, 2023 at 06:47
Craig,
Just a slight variation of topic.
Out of curiosity, What is the suggested service life of the tranny fluid by Isuzu?
AnswerID: 644248

Reply By: Member - Warren H - Tuesday, Aug 08, 2023 at 09:16

Tuesday, Aug 08, 2023 at 09:16
Another possible solution is to fit a transmission lock-up kit if they are available for the vehicle. A Google search does find one. Perhaps you can get more info on a Iszu dedicated forum. There are some pretty sophisticated kits available for Aisin transmissions but for others?
NT Pajero
2007 Goldstream Crown

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Follow Up By: RMD - Sunday, Aug 13, 2023 at 19:37

Sunday, Aug 13, 2023 at 19:37
Warren
It is a Torque Converter Lock Up system, not a transmission lock up! Also, the reason an auto excessively heats fluid is because it is in a mode which requires torque multiplication to some degree. If that is bypassed by causing a TC to lock up it's drive WILL often overload the small clutch in question and drastically shortens it's life expectancy. No one ever admits they had a TC replaced because of the clutch failed. It isn't made to carry much torque at all, only light duty device at best.
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Reply By: Geoff (Newcastle, NSW) - Monday, Aug 28, 2023 at 10:47

Monday, Aug 28, 2023 at 10:47
These people have an excellent reputation for their cooler kits, I have one in my Amarok.
I didn't drill any deeper as I don't which model DMax you have.

See: DMax auto kits
Geoff,
Landcruiser HDJ78,
Grey hair is hereditary, you get it from children. Baldness is caused by watching the Wallabies.

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