allmazda

My 95 ATX has the external transmission cooler that mounts on the bottom left side of the car. My replacement radiator has the trans cooler inside. Currently, I am using just the external cooler. I am wondering if I can run it to the radiator first then to the external cooler then back to the transmission.

My only concern would be about loss of pressure from the increase in distance?

ChrisMan287

iTrader: (34)

You can do that without issue, but why?

allmazda

Theoretically, lower the trans fluid temp.

ChrisMan287

iTrader: (34)

I think that would raise the fluid temp. The one in the radiator isn't much of a cooler to be honest.

JvG

The transmission cooler in the radiator serves two purposes. One is to cool the transmission fluid when it is hot. The other is to warm the fluid in the dead of winter in places like Alaska, Winnepeg, and Frostbite Falls, Minnesota.

Transmissions like to be a bit warm. Companies which make good auxiliary coolers have ones which have an internal thermostat for that reason. The fluid only circulates if it is above a certain temperature.

if you connect the auxiliary cooler to the one in the radiator, you would first cool, then reheat any super cold fluid.

Perhaps not a bad idea, yet the opposite of what you might have thought.
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allmazda

I am in NC so more heat than cold but we do get a few spurts of temps below 20 for a few days.

My plan was to go to the radiator first than to the oem auxiliary cooler. I have a cheap temp gun so I can try once it warms up.

My only concern would be the extra distance and loss of pressure.

JvG

Do you feel that you know more than the engineers
who designed our car?

Heat related AT failure does not come up much in this forum.

Seems the engineers did a good job.

CallMeThatOneGuy

iTrader: (2)

This statement always confuses me. Are you implying that an external cooler would not be beneficial for daily driving or just that he shouldn't cut the oem trans cooling out of the loop? I've really only heard of overheating 4at's from using a drop resistor mod or maybe a shift kit and very hard driving, so you aren't wrong about the toughness of the 4at.

JvG

What I mean is that by this time, 20 years after the car was built, we know what the cars strong and weak points are.

We have little problem with automatic transmissions which fail from overheating.
Most of us, and the general public, just use the transmission cooler in the radiator.

From time to time some person, generally a young one without much experience, trys to improve or second guess what the engineers did. Done properly, there might me some improvement, but often things are jerry-rigged, make do, half assed, or needless.

Old saying..... if it ain't broke, don't fix it.

Im trying to be diplomatic.

The oem cooler is sufficent. Cutting it out of the system could result in too LOW of a temperature in winter. Which is I mentioned that some of the better aftermarket coolers come with thermostats.

After market coolers have their place. For example, the Nissan Pathfinder and trucks circa 2007.

The seperation plate in the radiator corrodes.
so coolant under pressure enters the transmission fluid. Which in turn mixes coolant and atf.
This results in a dead trans and a 6k bill.
So aftermarket coolers with thermostat are installed instead. Because the engineers or more likely the accounting department screwed up.

allmazda

I have no idea what you are saying. The 95 Maxima came standard from the factory with an external cooler.

JvG

I own a 96 with MT. So I'm not as familiar with AT in out cars. When I replaced my radiatior with one from Koyorad, it had the lines for the trans cooler.

So I assumed that all maxima must also have the trans cooler.

It appears that the person who might not know what he is talking about is my humble self. Oops.

KSSilence

My AU Spec 95 Max came from factory with Both the external cooler and the Heat exchanger in the radiator, and from factory they are plumbed in series.

Im not sure which way round it is, but they are in series so that answers 1 part of it. If i were to take a stab at it, i'd say it goes Trans --> Ext Cooler --> Rad xChanger --> Trans. I could probably check the FSM for you in aa couple of hours and get a proper answer for you if you want me to.

allmazda

Cool. That would be great.

KSSilence

So i scoured the service manuals and couldn't find anything that mentions the AT Cooler system except for 1 page that simply shows the lines run to the rad in exploded view but thats it, and doesnt show them running to the aux cooler or transaxle.

Quick search shows the optimal ATF temp is around 80c Celsius, which is a bit below what the engine coolant runs at when up to temp (around 90-100c factory) Search also shows that every 15 degree increase above 80c cuts fluid life in half, so based on that.....

I would run it as follows: Transaxle --> Rad heat Exchanger --> External Cooler --> Transaxle.

that allows the coolant to warm the trans up when cold, but when operating and driving, having the external cooler after the rad heat exchanger should keep the fluid temps a bit cooler, extending fluid life.

One thing to remember with Auto Trans is that when the Torque converter is unlocked and is "slipping", especially when towing a heavy load starting off at the lights for instance, the torque converter creates a LOT of heat because the energy lost in the fluid coupling is transformed into heat.


When i get under the hood to replace the knock sensor which i plan to do in the next couple of days, i will take some photos of how the AT Cooler lines are connected in my car.

allmazda

Pictures would be great. Also I am not 100% sure but I think the OEM line on mine which runs from the ATX to external cooler has different sized hose ends. One of the hard lines either from the ATX or cooler has a bigger diameter.