120-160 on mine but I have a cooler with an electric fan and an adjustable thermostatic fan.
Automatic transmission temperature
- Thread starter Chevys_n_Hawgs
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Thought I would resurrect an old thread and introduce myself at the same time.
I have been lurking on the site for a few years and it has been a great resource so thanks to all who participate.
Anyway, I run a 4R70W in my 77 Bronco and would like to get some clarification.
Most everywhere I read I see the recommended operating temp for this transmission to be around 170. I also understand some oils can handle higher temps.
I measure my temp from a sending unit installed at the output cooling line (coming out of the converter I believe). My understanding is this is the hottest temperature in the transmission. I do this so I know whether the oil has been compromised and needs to be changed.
What is the typical differential between the output and the pan? This is obviously dependent on cooler setup so let's go with stock configurations.
Where does the temp you guys are reading on the computer measure from? I ask because I have a Baumann controller for my 4R70W and it reads the temp from the transmission too, just not sure where.
My concern is I run around 210 at the output and 190 at the stock temp sender (wherever that is). If the stock temp sender is at the pan, I want to try and add a second aux cooler to bring it down as I am currently running a 14,400btu aux cooler in conjunction with my aluminum radiator cooler.
I am space limited so the 11x9x.75 aux cooler may end up getting a brother stacked atop him and they share a single 10" cooling fan. Just not sure how efficient it would be to stack them like that.
Thanks fellas.
I have been lurking on the site for a few years and it has been a great resource so thanks to all who participate.
Anyway, I run a 4R70W in my 77 Bronco and would like to get some clarification.
Most everywhere I read I see the recommended operating temp for this transmission to be around 170. I also understand some oils can handle higher temps.
I measure my temp from a sending unit installed at the output cooling line (coming out of the converter I believe). My understanding is this is the hottest temperature in the transmission. I do this so I know whether the oil has been compromised and needs to be changed.
What is the typical differential between the output and the pan? This is obviously dependent on cooler setup so let's go with stock configurations.
Where does the temp you guys are reading on the computer measure from? I ask because I have a Baumann controller for my 4R70W and it reads the temp from the transmission too, just not sure where.
My concern is I run around 210 at the output and 190 at the stock temp sender (wherever that is). If the stock temp sender is at the pan, I want to try and add a second aux cooler to bring it down as I am currently running a 14,400btu aux cooler in conjunction with my aluminum radiator cooler.
I am space limited so the 11x9x.75 aux cooler may end up getting a brother stacked atop him and they share a single 10" cooling fan. Just not sure how efficient it would be to stack them like that.
Thanks fellas.
I would estimate the pan to be between 10 to 20 degrees less than the outbound fluid to the cooler. It's about what I've seen on the tundra when playing with a scan gauge. I recently moved my temp probe from the casing right behind the pan to the outbound cooler line, and I saw a 10F difference.
The tundra doesn't register over 100F in the winter. As soon as it's 70 outside, it eventually settles around 125. Summer, if I run the air, it gets a little higher. When towing in the past it stays locked around 160 unless I'm doing a long hill climb. This trans does has a rudimentary thermostat in the cooling circuit.
The 41Te in the chrysler runs hotter. I rarely run the A/C, and that also makes a big difference. Summer with A/C on it'll see 190 daily. Without it, 130-160 mostly with 190 if worked harder.
I prefer readings taken from the outbound line to the cooler. I feel like I get more "realtime" info.
The tundra doesn't register over 100F in the winter. As soon as it's 70 outside, it eventually settles around 125. Summer, if I run the air, it gets a little higher. When towing in the past it stays locked around 160 unless I'm doing a long hill climb. This trans does has a rudimentary thermostat in the cooling circuit.
The 41Te in the chrysler runs hotter. I rarely run the A/C, and that also makes a big difference. Summer with A/C on it'll see 190 daily. Without it, 130-160 mostly with 190 if worked harder.
I prefer readings taken from the outbound line to the cooler. I feel like I get more "realtime" info.
You are right about TC out as being the best place to take the temperature. The OP's range is about right. I'm used to readings in centigrade and 'normal' is somewhere around 80 C obviously depending on running conditions. The, very good, rule of thumb is that for every 10 C increase in temperature the fluid life is halved. I have tested this theory in a lab and proved it to be reliable.
Can you explain what lab experiments were used to determine that? I have a minor in chemistry and am familiar with the general rule that reaction rates are doubled/halved with each 10 C in temperature, but how do you measure the overall fluid life? What determines "life"?
Originally Posted By: Whitewolf
You are right about TC out as being the best place to take the temperature. The OP's range is about right. I'm used to readings in centigrade and 'normal' is somewhere around 80 C obviously depending on running conditions. The, very good, rule of thumb is that for every 10 C increase in temperature the fluid life is halved. I have tested this theory in a lab and proved it to be reliable.
Originally Posted By: Whitewolf
You are right about TC out as being the best place to take the temperature. The OP's range is about right. I'm used to readings in centigrade and 'normal' is somewhere around 80 C obviously depending on running conditions. The, very good, rule of thumb is that for every 10 C increase in temperature the fluid life is halved. I have tested this theory in a lab and proved it to be reliable.
The DKA oxidation test. That test has been commonly used in Europe for some considerable time and has been correlated with vehicle application. The test temperature is varied to suit the type of fluid being evaluated but with ATFs it was originally typically 160C raised to 170C during the 90s and now often 180C. Test duration is normally 192 hrs but that also can be and often is extended. See some of the ZF specs for examples.
Originally Posted By: Chevys_n_Hawgs
What temp it "too high" when it comes to ATF?
170f in the pan is claimed to be about optimal. Keep in mind with a big cooler it can over cool the unit in cold weather.
I use an inline thermostat, it really helps keep the temps stable at 160 -170 using a large cooler even in cold weather.
Without it i couldnt get the temp over 117f @30f or below ambient no matter how far i drove it.
What temp it "too high" when it comes to ATF?
170f in the pan is claimed to be about optimal. Keep in mind with a big cooler it can over cool the unit in cold weather.
I use an inline thermostat, it really helps keep the temps stable at 160 -170 using a large cooler even in cold weather.
Without it i couldnt get the temp over 117f @30f or below ambient no matter how far i drove it.
MolaKule
Staff member
Quote:
Can you explain what lab experiments were used to determine that? I have a minor in chemistry and am familiar with the general rule that reaction rates are doubled/halved with each 10 C in temperature, but how do you measure the overall fluid life? What determines "life"?
One of the oxidation tests for ATF is the:
CEC L-48-A-00 Oxidation Test (DKA)
Let's make sure we differentiate bulk or TC oil temperatures from clutch and band face temperatures which can spike to over 400F for short periods.
for example, one our testing services is :
DexronVI (TM) testing
Can you explain what lab experiments were used to determine that? I have a minor in chemistry and am familiar with the general rule that reaction rates are doubled/halved with each 10 C in temperature, but how do you measure the overall fluid life? What determines "life"?
One of the oxidation tests for ATF is the:
CEC L-48-A-00 Oxidation Test (DKA)
Let's make sure we differentiate bulk or TC oil temperatures from clutch and band face temperatures which can spike to over 400F for short periods.
for example, one our testing services is :
DexronVI (TM) testing
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Yes but don't forget that these temps and times are meant to accelerate the degradation. The DKA has been well proven in Europe and used over there for several decades. The test condition must also be able to sort the good from the bad in fluids.
So with all that information, I am curios if, in addition to the fluid lifespan / temperature charts we are familiar with, is there something that show temperature / exposure time? I would like to know how long I can sustain a certain temperature before it becomes critically degraded.
A great example is MolaKule's mention of intermittent spikes of 400*F. I know I will never see that temperature on my gauge, but brings to question the tolerance of the fluid at various temps and durations.
I would like to know how long I can run my temp at 200*F without risking degradation of the fluid. Or, better yet, how many times can I expose it to that temperature before degradation.
A great example is MolaKule's mention of intermittent spikes of 400*F. I know I will never see that temperature on my gauge, but brings to question the tolerance of the fluid at various temps and durations.
I would like to know how long I can run my temp at 200*F without risking degradation of the fluid. Or, better yet, how many times can I expose it to that temperature before degradation.
MolaKule
Staff member
Most of that information was derived from tests at OEM and additive maker's dynamometers and in fleet testing and is proprietary.
Again, we are over-thinking the situation (what we do here at BITOG) but here is some information.
The charts that every ATF manf. refers in terms of fluid degradation was taken from a 2004 study by GM engineers using Dexron-III (H revision) ATF as the test fluid. Oxidative and friction degradation models were developed to predict the fluid's "End-of-Life" or EOL. These models were compared to fleet test data to determine model correlation.
Oxidatively, End-of-Life (EOL) was defined as when the fluid's DeltaTAN increased by 2.5 during an ABOT test, which is much less severe the CEC test mentioned above. A TAN increase as you might remember is an indication that fluid acidity has risen to levels in which the fluid is no longer oxidatively stable.
Remember, this was a MINERAL-based ATF with none of the advanced, VII, FM or anti-oxidation chemistries that we have available today.
First temps stated are in C and F in "()."
First of all, the chart started at an ABOT temp of 140C(284) and went up to 160C(320).
The chart showed that the fluid at ABOT 140C(284) reached its EOL in about 1800 hours.
The chart showed that the fluid at ABOT 160C(320) reached its EOL in about 500 hours.
SO, a 20C(68) rise in fluid temp caused a 1300 hour decrease in fluid life.
Today's ATF chemistry is much more stable in terms of oxidatation, friction, and viscosity.
If in doubt, have the fluid analyzed and or do a pan drain and refill every 30,000 to 50,000 miles.
This not only refreshes the additives, but also reduces particulates.
Again, we are over-thinking the situation (what we do here at BITOG) but here is some information.
The charts that every ATF manf. refers in terms of fluid degradation was taken from a 2004 study by GM engineers using Dexron-III (H revision) ATF as the test fluid. Oxidative and friction degradation models were developed to predict the fluid's "End-of-Life" or EOL. These models were compared to fleet test data to determine model correlation.
Oxidatively, End-of-Life (EOL) was defined as when the fluid's DeltaTAN increased by 2.5 during an ABOT test, which is much less severe the CEC test mentioned above. A TAN increase as you might remember is an indication that fluid acidity has risen to levels in which the fluid is no longer oxidatively stable.
Remember, this was a MINERAL-based ATF with none of the advanced, VII, FM or anti-oxidation chemistries that we have available today.
First temps stated are in C and F in "()."
First of all, the chart started at an ABOT temp of 140C(284) and went up to 160C(320).
The chart showed that the fluid at ABOT 140C(284) reached its EOL in about 1800 hours.
The chart showed that the fluid at ABOT 160C(320) reached its EOL in about 500 hours.
SO, a 20C(68) rise in fluid temp caused a 1300 hour decrease in fluid life.
Today's ATF chemistry is much more stable in terms of oxidatation, friction, and viscosity.
If in doubt, have the fluid analyzed and or do a pan drain and refill every 30,000 to 50,000 miles.
This not only refreshes the additives, but also reduces particulates.
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That clears things up a bit. With all the advanced fluids we have today, I wonder why similar testing has not been accomplished other than the fact that the industry probably sells a lot more fluid at a higher price more frequently since we are probably changing fluid more than necessary based on old test results.
If the testing was done based on hours rather than miles I wonder why we use mileage as a primary means of measurement for fluid maintenance. Sounds like I should just stick a Hobbs meter in the cab
Thanks again.
If the testing was done based on hours rather than miles I wonder why we use mileage as a primary means of measurement for fluid maintenance. Sounds like I should just stick a Hobbs meter in the cab
Thanks again.
An addition to this topic, last fall I purchased an '15 F350 with the 6.7 Powerstroke, 6 speed auto 6r140. It has a digital transmission temp readout. My first extended drive I was shocked that the trans temp regularly stayed at 200f + - a few degrees.
This is obviously where Ford wants the temp to stay as its thermostatically controlled, but just goes along with what Moalkule has already stated with the advancement of fluids/additive packages higher sustained temps are not only possible, but much more efficient.
This is obviously where Ford wants the temp to stay as its thermostatically controlled, but just goes along with what Moalkule has already stated with the advancement of fluids/additive packages higher sustained temps are not only possible, but much more efficient.
MolaKule
Staff member
Originally Posted By: chuzie
... With all the advanced fluids we have today, I wonder why similar testing has not been accomplished other than the fact that the industry probably sells a lot more fluid at a higher price more frequently since we are probably changing fluid more than necessary based on old test results...
Thanks again.
It has been;
Quote:
Most of that information was derived from tests [done] at OEM and additive maker's [facility] dynamometers and in fleet testing and is proprietary.
That info is not made public.
One could do ABOT testing and using the equations developed in the papers, make EOL predictions.
... With all the advanced fluids we have today, I wonder why similar testing has not been accomplished other than the fact that the industry probably sells a lot more fluid at a higher price more frequently since we are probably changing fluid more than necessary based on old test results...
Thanks again.
It has been;
Quote:
Most of that information was derived from tests [done] at OEM and additive maker's [facility] dynamometers and in fleet testing and is proprietary.
That info is not made public.
One could do ABOT testing and using the equations developed in the papers, make EOL predictions.
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MolaKule
Staff member
Originally Posted By: roadrunner1
An addition to this topic, last fall I purchased an '15 F350 with the 6.7 Powerstroke, 6 speed auto 6r140. It has a digital transmission temp readout. My first extended drive I was shocked that the trans temp regularly stayed at 200f + - a few degrees.
This is obviously where Ford wants the temp to stay as its thermostatically controlled, but just goes along with what Moalkule has already stated with the advancement of fluids/additive packages higher sustained temps are not only possible, but much more efficient.
200F is 93.3C, below where accelerated oxidation occurs.
Recall that the ABOT test data (above) started at 140C or 284F.
In my test mule ('03 PF, 3.5L V6), the ATF temp varies between 175F and 190F on a hot summer day.
I'll go out on a limb here and predict that if the average ATF SUMP temp is kept below 110C or 230F, your ATF should not show accelerated oxidation.
An addition to this topic, last fall I purchased an '15 F350 with the 6.7 Powerstroke, 6 speed auto 6r140. It has a digital transmission temp readout. My first extended drive I was shocked that the trans temp regularly stayed at 200f + - a few degrees.
This is obviously where Ford wants the temp to stay as its thermostatically controlled, but just goes along with what Moalkule has already stated with the advancement of fluids/additive packages higher sustained temps are not only possible, but much more efficient.
200F is 93.3C, below where accelerated oxidation occurs.
Recall that the ABOT test data (above) started at 140C or 284F.
In my test mule ('03 PF, 3.5L V6), the ATF temp varies between 175F and 190F on a hot summer day.
I'll go out on a limb here and predict that if the average ATF SUMP temp is kept below 110C or 230F, your ATF should not show accelerated oxidation.
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Originally Posted By: chuzie
If the testing was done based on hours rather than miles I wonder why we use mileage as a primary means of measurement for fluid maintenance.
The data taken from fleet test oil condition has to be compared with data from tests such as the DKA oxidation in order to correlate test hours at a given temperature with vehicle mileage. This is obviously necessary since vehicle usage is normally recorded in terms of mileage and not hours.
If the testing was done based on hours rather than miles I wonder why we use mileage as a primary means of measurement for fluid maintenance.
The data taken from fleet test oil condition has to be compared with data from tests such as the DKA oxidation in order to correlate test hours at a given temperature with vehicle mileage. This is obviously necessary since vehicle usage is normally recorded in terms of mileage and not hours.
MolaKule
Staff member
Originally Posted By: chuzie
.. I wonder why similar testing has not been accomplished other than the fact that the industry probably sells a lot more fluid at a higher price more frequently since we are probably changing fluid more than necessary based on old test results...
That part of your statement has not been established as fact but infers some kind of collusion or conspiracy that has not been proven.
.. I wonder why similar testing has not been accomplished other than the fact that the industry probably sells a lot more fluid at a higher price more frequently since we are probably changing fluid more than necessary based on old test results...
That part of your statement has not been established as fact but infers some kind of collusion or conspiracy that has not been proven.
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MolaKule
Staff member
In a nutshell, here is how the industry conducts studies in order to make predictions:
1.) An Hypothesis is put forth as to how the system under study behaves in terms of its physics (thermodynamics, mechanics, and chemistry),
2.) A predictive Mathematical model is developed based on the physics of the hypothesized system,
3.) Physical Tests, such as Lab and Fleet tests are executed and data collected,
4.) Feedback (data) from the Physical Tests are compared to the model to see how and if the physical data correlates with the model,
5.) If the correlation between the proposed model and physical data agrees, the predictive (mathematical) model is accepted,
6.) If the correlation between the proposed model and physical data does not agree, the predictive (mathematical) model is modified or redefined.
I am going to place this in the White Papers section as well.
1.) An Hypothesis is put forth as to how the system under study behaves in terms of its physics (thermodynamics, mechanics, and chemistry),
2.) A predictive Mathematical model is developed based on the physics of the hypothesized system,
3.) Physical Tests, such as Lab and Fleet tests are executed and data collected,
4.) Feedback (data) from the Physical Tests are compared to the model to see how and if the physical data correlates with the model,
5.) If the correlation between the proposed model and physical data agrees, the predictive (mathematical) model is accepted,
6.) If the correlation between the proposed model and physical data does not agree, the predictive (mathematical) model is modified or redefined.
I am going to place this in the White Papers section as well.
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