Automatic Gearbox Separate Inter-Cooler, do they really work?!

[sae70]

Automatic Gearbox Separate Oil Cooler - Do they really work?!

When I bought Swampy I inherited an after market separate oil cooler installation that one of her previous owners had a well known 4x4 specialist company fit for them. After some consideration I re-installed the oil cooler basically in the same location but a little lower. I did this so I could re-fit the drivers side turbo inter-cooler scoop that had been removed by the original installer to fit the after market automatic gearbox oil cooler and so that I could also run the pipework in a more sympathetic route with some protection where it pass's through the front panel, again something not done by the previous installer!

So, following a trip to Wales back in Feb/March all went very well with no running troubles and a great weekend was had

Now, following a trip up to Wales this weekend just gone with very much warmer weather conditions, temperatures in the mid twenties I had to pull over three times to allow the automatic gearbox to cool down as the 'Auto O/T' warning light had come on!!! This does not take very long and just requires the bonnet to be opened and the engine left on tick over for 5/10min, but not convenient or what one would like, to say the least!!!

I've also been struggling with getting her to pull away this weekend and leading up to it with an almost embarrassing pause and slow start to getting off the mark from throttle down! Not every time, but in the majority of occasions! I started to think this was down to throttle response as the revs do nothing for about one or two seconds before climbing after sticking your foot down! Then when the rev's do climb, the auto-box oil blender picks up enough speed and she's off Usable, but not great performance in my mind

I lost no oil when I moved the auto-box inter-cooler, all that came out went back in and the pipes remained pretty much the same length. When I've checked the gearbox oil level it has always appeared to me to be high, but not knowing the correct procedure for checking it I've assumed my method to be incorrect rather than the level. For example on my Volvo you have to check the auto-box oil level with the oil at 86°C and the engine running and there is only one 'Low' & 'High' level mark. On Swampy there is two levels that you can check the the oil at and they are 'Cool' odd wording I thought, not 'Cold' and 'Hot'?! When I check the level I've always done it 'Hot' with the engine turned off and it's always been over the 'Hot' high level mark by at least an inch or more! Putting this down to poor method I've ignored it as I've not had any trouble till this weekend just gone.

Is there a manufacturers preferred method for checking the Automatic Gearbox oil level?

I've started to wonder this weekend if the oil level appears high in the gearbox because the retro fitted oil cooler is higher than the gearbox and maybe the extra oil that is now in the circuit is running back to the box?! Maybe I should check the oil level with the engine running?!

I'm half considering doing away with the retro fitted oil cooler and putting her back to OE layout with the pipework connected to cooler tube in the base of the radiator as this should just work, shouldn't it?

I know the argument about removing the heat load loading of the auto-box away from the engine cooling circuit and that's fine I understand that, but the other argument is about removing the potential for a failure in this allowing engine cooling water into the gearbox! Has anyone actually had this happen or read anything about anyone that has had this happen to them? If so could you signpost me to it

I'd be very interested in others thoughts and experiences in this subject and any information on how to check for the correct oil level with and without a retro fitted oil cooler

 

[Doodle]

Not LC specific, but coolant and ATF mixing is/was a well known issue with Valeo rads.

Pretty sure you're meant to check autoboxes at hot with the engine running - that probably explains why the level is high.

Also worth considering is that the trans oil cooler is no longer being cooled by the viscous fan (depending on your installing). It'll work great when you have airflow, but not necessarily so well for slow speed work offroad.

 

[Paulpen]

Ill be getting my seperate cooler fitted when I find some time and taking it away from the standard radiator.

What colour is your fluid and what does it smell like ? Brown and burnt is not good whereas red and oily is !

Also how is your cooler fitted - ive heard that if the inlet and outlet of the cooler dont point upwards you get air trapped in it ?

 

[uHu]

Always check level w engine running. Hot level is more accurate than cold.

There has been a few instances of colant/atf mix. It seems to be due to old age, or radiator damage because of some hit offroad or while going through snowdrifts.

Water conducts and stores heat very well, and is an excellent vehicle for your heat. But, as far as i've understood, the main reason for having an atf compartment in the main radiator is for heating the atf/box when the temps are low. The auto-box will not perform well when cold, and with this design, the box will always reach the same temp as the engine coolant. The 100 TD has a similar design, only with a separate atf cooler in addition. The ATF goes first through the separate cooler, then through the main rad.

 

[sae70]

There's some very interesting points here that I would like to discuss at length and will do later on, but am rushing out to a meeting!!!

Here's some photo's

Before I moved it, so as installed by professional company!






And after I moved it, installed by an amateur enthusiast

 

[silvercruiser]

Me personally, i would put it back to standard but maybe invest in a new yota rad for peace of mind. I have never had my auto box temp light come on( i hope im not tempting fate now) and i have towed my mum and dads caravan to Dorset and back with the sun blazing with no problems at all and im now sitting on 175k miles. when i bought the l/c 5 years ago i did change the rad as i had also been reading about the problems of the two fluids mixing. i aslo took it across to Italy last year up the mountains etc with out a hitch.

 

[Paulpen]

Personally id have it up the other way to prevent air locks and also so its less likely to drain overnight etc (both those reason may be wrong though !)

When i had my Surf it had the standard cooler and a temp gauge measuring what went into the cooler - on the motorway it would often sit at 40C or below yet when using the lower gears in the lanes doing decents etc in the snow I managed to get the light to come on like you had ! (come on at 130C and goes off at 110C from what I remember in the manual).

I myself a stuck in two minds - do you run the aftermarket one only and risk over cooling or run the aftermarket one into the standard one to try and keep a stable temperature ?

With the risk of the coolant and oil mixing I think im going to run aftermarket only with the gauge and see what temps I get - bearing in mind that the coolant at the bottom of the radiator on mine seems to be around 30C at idle when warm I dont think the coolant really warms it at all. Maybe it more warms it from 0C to about 20C but after that the gearbox is generating its own heat and the heating aspect is no longer required.

All personal theory so curious what other think

 

[jbecks]

Steve, your aftermarket oil cooler is fitted incorrectly, the oil cooler should be fitted right next to the aircon rad, just like how the aircon rad sits next to the coolant radiator, the way your ATF cooler is fitted also has a similar effect to placing some cardboard over the front of your rad. Your cooler is also facing the wrong way, the inlet and outlet should face to either the sides or upwards. I have a B&M Supercooler and I have not had any issues yet but I fitted the same cooler that alot of the American guys fitted to their trucks and have taken temperature readings, so I know it will be ok on my truck

Toyota choose the existing method because its cheaper to produce, however in certain situations it too is not sufficient enough to cool the tranny particularly when its hot and towing. But they have obviously tested and worked our the right size to give general trouble free issues but you could do what I did and just fit one that has had lots of testing all ready The Radiator does not heat up the ATF fluid any quicker due to the coolant will not be circulating through the radiator unitl the thermostat starts to open, the ATF cooler I have does have a cold oil bypass.

Here's mine;

The fan really pulls air through it hard when idling. With your engine idling put your hand infront of your ATF rad and see how much air is being drawn through?

this is a highly scientific airflow test, (not mine, but rather some guy in the US)

Regards worrying about whether the rad fails and your coolant mixes with ATF fluid, as longs you catch it early all that should be required to fix it, is a good a atf and engine flush...and she should be back on the road!

 

[fridayman]

Referring to the op - It doesn't sound like this setup is working very well. I've towed my camper trailer on very soft sand tracks and dunes for up to an hour in the Aussie summer and never had any problems. My setup has a slightly bigger cooler inline with the original and it is right up against the rad (I've also heard there shouldn't be a gap). My viscous fan is also always on.

Have you checked your coolant recently to see if you have pink milkshake? I've had a rad fail at the cooler union on the bottom left - when I touched the union it came off... This is a common place for them to fail, so you can give yours a wiggle if you are worried about it. I knew something was up when it didn't pull away like it should a couple of times.

 

[sae70]

Not LC specific, but coolant and ATF mixing is/was a well known issue with Valeo rads.

Pretty sure you're meant to check autoboxes at hot with the engine running - that probably explains why the level is high.

Also worth considering is that the trans oil cooler is no longer being cooled by the viscous fan (depending on your installing). It'll work great when you have airflow, but not necessarily so well for slow speed work offroad.

Thank's for reiterating the coolant & ATF contamination point, I shall take that on board I think that you are correct about checking the ATF level with the engine running and would make sense as to why mine appears to be high. I think that I'm coming to the conclusion that the ATF cooler is mounted far to far away from the air flow through the rads and shall look at moving it up against the air-con rad.

Ill be getting my seperate cooler fitted when I find some time and taking it away from the standard radiator.

What colour is your fluid and what does it smell like ? Brown and burnt is not good whereas red and oily is !

Also how is your cooler fitted - ive heard that if the inlet and outlet of the cooler don't point upwards you get air trapped in it ?

The fluid in my gearbox is translucent red and smells as it should. Even with the 'Auto O/T' warning light coming on over the weekend. I think that this must catch it just in time that if stopped and left to cool allows it to do so without any further harm. It's interesting your thoughts about mounting the cooler the other way up. I wonder if any air locks would occur in the circuit due to the type of pump used?!

Always check level w engine running. Hot level is more accurate than cold.

There has been a few instances of colant/atf mix. It seems to be due to old age, or radiator damage because of some hit offroad or while going through snowdrifts.

Water conducts and stores heat very well, and is an excellent vehicle for your heat. But, as far as i've understood, the main reason for having an atf compartment in the main radiator is for heating the atf/box when the temps are low. The auto-box will not perform well when cold, and with this design, the box will always reach the same temp as the engine coolant. The 100 TD has a similar design, only with a separate atf cooler in addition. The ATF goes first through the separate cooler, then through the main rad.

I think that checking the oil level with the engine turned off has been my mistake in getting an accurate level reading. I should have know considering how much time I spent flushing and checking the oil level on our Volvo when the auto-box started to play up! Water is an excellent conductor of heat and we in fact reduce its performance by putting Anti-Freeze in it can you believe! Straight H2O is one of the best and most efficient ways to remove unwanted heat, second only to Brine as I understand, but who would want that in the cooling system?!! That's an interesting idea with regards to running both cooling/heating solutions and clearly something that Toyota feel works if that's how they've set up the 100 series. I wonder why they've done it like that?

Me personally, i would put it back to standard but maybe invest in a new yota rad for peace of mind. I have never had my auto box temp light come on( i hope im not tempting fate now) and i have towed my mum and dads caravan to Dorset and back with the sun blazing with no problems at all and im now sitting on 175k miles. when i bought the l/c 5 years ago i did change the rad as i had also been reading about the problems of the two fluids mixing. i also took it across to Italy last year up the mountains etc with out a hitch.

I was right there with you on Sunday Joe Back to the original method of cooling it was going to be for me first thing Monday morning. Having read what others are saying now though it may be that I can get a reliably working ATF oil cooling system going with what I have and keep the engine and the gearbox cooling separate

Personally id have it up the other way to prevent air locks and also so its less likely to drain overnight etc (both those reason may be wrong though !)

When i had my Surf it had the standard cooler and a temp gauge measuring what went into the cooler - on the motorway it would often sit at 40C or below yet when using the lower gears in the lanes doing decents etc in the snow I managed to get the light to come on like you had ! (come on at 130C and goes off at 110C from what I remember in the manual).

I myself a stuck in two minds - do you run the aftermarket one only and risk over cooling or run the aftermarket one into the standard one to try and keep a stable temperature ?

With the risk of the coolant and oil mixing I think im going to run aftermarket only with the gauge and see what temps I get - bearing in mind that the coolant at the bottom of the radiator on mine seems to be around 30C at idle when warm I dont think the coolant really warms it at all. Maybe it more warms it from 0C to about 20C but after that the gearbox is generating its own heat and the heating aspect is no longer required.

All personal theory so curious what other think

Like you, I have no idea if there is a good, bad or an ugly way up to mount these things and if any have a different effect on how the cooling works over any other. This probably needs further investigation to be clear as to the effects of different mounting orientations on the performance of the system There's some interesting temperatures readings that you've quoted. There was no way my oil cooler was at any thing less than 100°C when it was O/T and your figure of 130°C sounds more like it! You could just about tap touch the top of the engine rad for a second or two, but the oil cooler was very very hot! Almost sole plate of an iron hot!!! I can't imagine the water in my engine cooling circuit being much below 80°C after running for an hour or so, as the thermostat starts to open at 82°C and is fully open at 95°C

Steve, your aftermarket oil cooler is fitted incorrectly, the oil cooler should be fitted right next to the aircon rad, just like how the aircon rad sits next to the coolant radiator, the way your ATF cooler is fitted also has a similar effect to placing some cardboard over the front of your rad. Your cooler is also facing the wrong way, the inlet and outlet should face to either the sides or upwards. I have a B&M Supercooler and I have not had any issues yet but I fitted the same cooler that alot of the American guys fitted to their trucks and have taken temperature readings, so I know it will be ok on my truck

Toyota choose the existing method because its cheaper to produce, however in certain situations it too is not sufficient enough to cool the tranny particularly when its hot and towing. But they have obviously tested and worked our the right size to give general trouble free issues but you could do what I did and just fit one that has had lots of testing all ready The Radiator does not heat up the ATF fluid any quicker due to the coolant will not be circulating through the radiator unitl the thermostat starts to open, the ATF cooler I have does have a cold oil bypass.

Here's mine;

The fan really pulls air through it hard when idling. With your engine idling put your hand infront of your ATF rad and see how much air is being drawn through?

this is a highly scientific airflow test, (not mine, but rather some guy in the US)

Regards worrying about whether the rad fails and your coolant mixes with ATF fluid, as longs you catch it early all that should be required to fix it, is a good a atf and engine flush...and she should be back on the road!

It appears that relocation of my oil cooler closer to the existing radiators should be the first step towards dealing with this and I shall probably have to mount it vertically with it's outlets coming away from one side due to the shape and size of the thing. Does it matter if the I/P or O/P are at the top or the bottom of the cooler when it's mounted on its side? Think I'm going to stick with the same oil cooler as it's a good quality British made one of a very similar size in terms of cooling to the one that you have got there jbecks. The difference in construction between the two appears to be that the one you have would be termed 'Heavy Duty' and thus less susceptible to damage. It would be good to get some idea of the temperatures that the Americans were finding with their installations so I could compare and contrast with mine once I've relocated it. Do you have them written down or a link to the site? What is a cold oil bypass and how does it work? I put my hand in front of the rads this morning and there is quite a pull through that you can feel when your hand is up against the them. This is soon lost as you pull your hand away My only thoughts about putting the ATF cooler up against the existing rads is that you re-introduce the heat load from the gearbox back to the engine cooling circuit as I found over the weekend when putting on the air-con increased the engines operating temp by 4 to 6°C. Maybe a separate cooling fan and control circuit would be another option for the gearbox oil cooler. I was also considering leaving the ATF cooler where it is and fitting a cowl on the back of it that went up to the face of the rad.

Referring to the op - It doesn't sound like this setup is working very well. I've towed my camper trailer on very soft sand tracks and dunes for up to an hour in the Aussie summer and never had any problems. My setup has a slightly bigger cooler inline with the original and it is right up against the rad (I've also heard there shouldn't be a gap). My viscous fan is also always on.

Have you checked your coolant recently to see if you have pink milkshake? I've had a rad fail at the cooler union on the bottom left - when I touched the union it came off... This is a common place for them to fail, so you can give yours a wiggle if you are worried about it. I knew something was up when it didn't pull away like it should a couple of times.

I think that you are bang on and the fact that the cooler is not mounted hard up against the other rads is clearly having a very large effect on the efficiency of the coolers cooling when moving slowly and working the vehicle hard! I'm going to move the cooler to a better location and keep plumbing the original in rad cooler in addition as an option if it's still struggling. Although the whole point for me of fitting a separate ATF oil cooler is to remove the heat load from the engine cooling circuit and the chance of a failure causing oil and water contamination! I'm always checking all of my fluid levels throught the vehical and ran through them all only Thursday before going up to Wales. I'm happy to report them all to be as they should be and that there is no side wall damage to the tyres and all of the UJ's are greased with no play and there are no leaks from any thing for a change and the rear shocks are now tight and as they should be again. I found them to be loose and sloping around in their top mounts on Thursday!!!

I removed the drivers side turbo inter-cooler scoop this morning to get a better look at the ATF cooler and took a couple of photos.

 

[Beau]

I'd take it back to standard way as well. I've only had the transmission light come on once with me and it was towing up a long hill and this was with a 12 year old radiator.

New radiator has been in for a good few years now and not had the light appear back ever since...

 

[froggy Steve]

All this talk has me knocking the separate cooler on the head! I think I may well get a new set of oil pipes from Simon and a brand new radiator.......next question...who's rad is best? Millners?

Sent from my GT-P5110 using Tapatalk

 

[sae70]

I'd take it back to standard way as well. I've only had the transmission light come on once with me and it was towing up a long hill and this was with a 12 year old radiator.

New radiator has been in for a good few years now and not had the light appear back ever since...

All this talk has me knocking the separate cooler on the head! I think I may well get a new set of oil pipes from Simon and a brand new radiator.......next question...who's rad is best? Millners?

Sent from my GT-P5110 using Tapatalk

I think you boys may be right I'm going to stick with what I have for now and see if I can make it work I'm not so sure that the Milners or any other pattern radiators are as good as an OE one! I remember some talk about single core and double core What about this as an idea What about a bespoke Alisport one with the engine cooling and the ATF cooling built into the same unit, but separate from one another How cool would that be

 

[Paulpen]

It does all make for a good debate !

If mounting on the side id assume you had the oil coming in a the bottom and out at the top so any air that does get sutuck goes back to the box.

I may get my gauge plumbed in on the standard cooler and get some readings before making any changes so at least then we might all have some figures to work with

Has anyone ever cut up a damaged radiator as id be crious what the OEM ATF cooler actually looks like - I imagine its a single or twin loop of pipe but having never cut one up I dont really know !

 

[jbecks]

Steve,

If you mount the cooler facing the side, the upper should be the inlet and the outlet should be at the bottom. Hot inlet top, cold outlet bottom. regarding mounting the cooler against the aircon rad..the reason why they mount them all next to each other is its the most efficent way of cooling the rads down and not restricting airflow, as soon as you have a gap the first radiator also acts like shield causing worse cooling for the radiators behind them, its the reason why all cooling radiators are always mounted next to each other without a slight gap. regarding the cold oil bypass, I dont belive there is any type of thermostat inside but rather just a wider hole

"The Super-Coolers intended for automatic transmission fluid also offer an additional feature known as ?Low Pressure Drop?. The coolers assembled with hose barb ends include a unique bypass feature allowing a controlled amount of ATF to bypass the stacked plate core when the fluid is cold. This is beneficial in cold climate areas to guard against lube system failure. Controlled by viscosity, fluid is returned directly to the lube circuit through bypass openings in the stacked plate core."

My cooler has a BTU of 13,000,

Some readings;

5hour drive highway between 60 degrees and 87 degrees, around town: 85 degrees...In Missouri
Warm weather, average between 70 - 80degrees. Towing a 3,600 lb trailer up a really steep hill the temperature hit 106 degrees for 20seconds, most of the journey the temperature was around 90degrees. The 106 degrees was the highest temp reading I saw which was towing up a really steep hill.

This was on the a340f transmission which is very similar to our a343f transmission, which are very similar so should not effect the results, the ratios are exactly the same except for the other drive is greater on ours but we also have an extra 2.7 litres of oil inside ours.

I think the O/T light comes on around 150degrees.


Before you buy a new radiator and return your system to the stock setup, I would relocate your cooler and change the orientation of the atf cooler. I would avoid buying a cheap radiator and either go toyota or from a good company as the time and cost of flushing the engine and transmission will more than cover the price difference between a cheap and expensive radiator.

 

[silvercruiser]

It does all make for a good debate !


Has anyone ever cut up a damaged radiator as id be crious what the OEM ATF cooler actually looks like - I imagine its a single or twin loop of pipe but having never cut one up I dont really know !

 

[silvercruiser]

 

[AndyCook]

I fitted ATF oil cooler inline on Wugg, ATF went through in-rad cooler first. I had fitted a new roughtrax radiator in 2009 since original was coming upto 10yrs old and that's often the age they can start to fail.

The original system worked well with stock tyre size in Pyrenees and long climbs on hot days
But in hot alpine climbs the following year with larger diameter tyres I had ATF light come on a few times.

I fitted the ATF cooler after that and never saw the ATF light come in again even in alps in summer
I also fitted temp gauge to monitor ATF temps


Sent from my iPad using Tapatalk

 

[David]

I fitted ATF oil cooler inline on Wugg, ATF went through in-rad cooler first. I had fitted a new roughtrax radiator in 2009 since original was coming upto 10yrs old and that's often the age they can start to fail.

The original system worked well with stock tyre size in Pyrenees and long climbs on hot days
But in hot alpine climbs the following year with larger diameter tyres I had ATF light come on a few times.

I fitted the ATF cooler after that and never saw the ATF light come in again even in alps in summer
I also fitted temp gauge to monitor ATF temps


Sent from my iPad using Tapatalk

Since I have had the truck i have had a bit of rubber mat blocking it off, as it kept it to cool in the winter

 

[Paulpen]

Good pictures - so its basically a bit of copper pipe ?!. I wonder how fast it passes through that as I cant imagine it cools alot !

As for the inlet / outlet if mounted sideways - once thinking about it the hot at the top and cold at the bottom makes sense as posted above