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Discussion Starter · #1 · (Edited)
AX4N transmission. Reading the internal transmission sensor via OBD - does anybody have ideea how reliable is the reading?

I have read on my "noisy" transmission some 385 deg F!!!
That might be the case (I think I have a differential rumbling) but on my Explorer I am reading 312 deg F and it has an auxiliary cooler - that is still too much from what I read online.

LE: Nevermind, it was from the software that I was using - I updated Torque to 1.4.90 because:
Changes:
ELM323 support
Screenshots to Google+ fix
Transmission temperature fix
AIDL plugin API update
Wider fault code support
Accelerometer/GPS fixes
Internal PID calculation support
It shows 160 F now (a short drive, engine at the 198 F temperature)... I will check again tommorow after a longer drive.
 

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Discussion Starter · #3 ·
I did drive the Explorer today to get a baseline and transmission temperature was in the 140-150 F range (155 shortly when I "punch it").
Tommorow is the Sable turn to monitoring.
 

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thats much better. temp should be below 200 f at all times.
I wouldn't say that necessarily. Since you have the cooler that is integrated into the radiator, I would say that the temp shouldn't go above 210-220F just based on engine coolant operating temperatures.

High temperatures are mostly bad because they break down the transmission fluid and allow for wear to occur. Higher operating temperatures means that you need to increase how often you are getting your transmission serviced. (Or you might need to add an auxiliary cooler.)
 

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I wouldn't say that necessarily. Since you have the cooler that is integrated into the radiator, I would say that the temp shouldn't go above 210-220F just based on engine coolant operating temperatures.

High temperatures are mostly bad because they break down the transmission fluid and allow for wear to occur. Higher operating temperatures means that you need to increase how often you are getting your transmission serviced. (Or you might need to add an auxiliary cooler.)
the engine temp is a whole different beast. a good trans temp should be around 140 - 160 f
 

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Discussion Starter · #6 · (Edited)
Today the Explorer shows 157 F at noon (90 F outside). But it has a suplemmental cooler.
For the Sable, without that cooler, I was expecting something close of the water temperature (190-200 F)- I will test that tomorrow.

LE: It got up to 178 F on rush hour traffic - water temp was 189 F.
 

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Discussion Starter · #7 ·
Mercury Sable data (air 80F, raining):
Highway, 65mph - water 180F, transmission 156F.
Stoplights, traffic - water 188F, transmission 176F.

Looks like the airflow (on highway speeds) cools the transmission (bottom of transmission oil pan). Not so much at stoplights :)
 

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I have a SHO ATX cooler mounted under my radiator on the header panel and disconnected the stock cooler tube. My fluid runs from the trans, through the radiator cooler and then to the aux SHO cooler and back into the trans. I also have a digital temp gauge to monitor the trans temps. When you dont have a fan behind a trans cooler it doesnt do alot in traffic, you need air flow over it to cool the fluid. I have noticed temps as high at 195 / 200 AFTER highway driving while sitting in traffic, but as soon as the air flow picks up it will drop the temp. In the past couple weeks going to shows I have noticed some interesting temps.

After 1 hour on the freeway at 70mph with an air temp of 65-70 the trans was at 150/155. after getting off the freeway I was on back roads doing 50mph and ran through some fog banks, dropping the temp fast to 130/135. Later in the day the air temp has in the high 90's. At 70mph on the freeway, the trans was running at 180/184. I have also noticed that up and down hill stretches will change the temp as much as +/- 2 deg. and following traffic on the highway will also change the temp as much as +5 to 10 deg depending on how close and how long i'm following them. Another thing that changes the temp is if I am running cruise control or not. With cruise on, it seems to run a few degrees cooler.

I have been told the best temp for our transmissions on the highway is between 160 & 180. Its true that heat will breakdown the fluid and in turn cause trouble in the long run. My '99 trans ran so hot that it would steam anywater that got onto the original tube cooler before it finally burned up and destroyed itself.
 

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Mercury Sable data (air 80F, raining):
Highway, 65mph - water 180F, transmission 156F.
Stoplights, traffic - water 188F, transmission 176F.

Looks like the airflow (on highway speeds) cools the transmission (bottom of transmission oil pan). Not so much at stoplights :)
The design of the heating/cooling exchanger in the rad is intended to make the tran fluid about the same as engine coolant. Steady state temp of trans helps it run consistent.

In the early days of automatics there were some air cooled trans. The radaitor temp stabilization has been around for a long time for a reason.

-chart-
 

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Discussion Starter · #10 ·
From what I saw on the Explorer and Sable, an additional cooler without a dedicated fan does nothing in normal traffic (excepting here pulling a trailer).
On highway there is not enough heat generated to matter - the bottom of transmission pan looks like is enough surface to allow cooling of fluid under the water temperature.
On stop-and-go traffic, there is not enough airflow in the auxiliary cooler. An electric fan with thermostat would help there. Without, looks like the bottom of the transmission still helps cooling if the car moves with some 35mph...
 

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High temperatures are mostly bad because they break down the transmission fluid and allow for wear to occur. Higher operating temperatures means that you need to increase how often you are getting your transmission serviced. (Or you might need to add an auxiliary cooler.)
That is why running synthetic transmission fluid gives you a little extra safety factor. I run Wolfs Head synthetic, great fluid at a reasonable cost.
 

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From what I saw on the Explorer and Sable, an additional cooler without a dedicated fan does nothing in normal traffic (excepting here pulling a trailer).
On highway there is not enough heat generated to matter - the bottom of transmission pan looks like is enough surface to allow cooling of fluid under the water temperature.
On stop-and-go traffic, there is not enough airflow in the auxiliary cooler. An electric fan with thermostat would help there. Without, looks like the bottom of the transmission still helps cooling if the car moves with some 35mph...
Trans should not make much heat in normal operation. The main heat generator is the torque conv when not locked. When out of OD and in gear 3, no torque conv slip, no gears, just straight through and there should be minimum heat to get rid of. Reason to not tow in OD in any case.

Back in earlier times, the Essex engine was programmed to unlock the torque conv and stay in gear 4, just let it slip under modest loads, not hard enough to downshift. Ford claimed it was a "comfort" issue buyers liked. I have had 2 Exxex in Sables, 2 in Lincolns. I did not like the dragged out shifts and slow to engage lockup.

-chart-
 

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Discussion Starter · #13 · (Edited)
Well true, low heat for highway - and I saw low temperatures.
But in city driving at rush hour the torque converter might never lock. And exactly then the suplemental cooler won't help much without forced airflow.

Now I understand why some high milage transmissions are still OK (ones driven mostly on highway), while others fail at 1/4 of that distance - the ones that are used in daily short comutes, in high traffic areas.

Hmm, I wonder if something like this is not a good ideea sice it holds more oil and is made of finned aluminium:

 

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I looked into other trans pans, even making one. The problem is clearance under the car. Chances are you would rip it open at some point, then your stuc anyways.
 

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Discussion Starter · #15 ·
Hmmm, sadly you are right. My 15 yr old springs are not really helping.
Maybe I'll do it on the Exploder.
 

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At what temp does the "check transmission" come on the EVIC? My '04 at 56k miles showed this climbing the hills to and from So Utah from No Utah. I put an aux cooler in at 100k and it would show the check trans only when hot outside and generally once during the drive down. That lasted a good 150k; I change the trans oil every 70k and now at 250k, the check trans will come on driving 70mph on the freeway when its 95+ outside - never did that before. I know Im on borrowed time, but I have been religious about maintenance on this beast.
With all of that said, what is the temp at which the "check transmission" indicator comes on the EVIC?
 

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Today the check transmission came on the evic after 50 miles of freeway at 70mph with ambient temp of 77. Thoughts?
 

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^^^^ how do you know the check trans light is on due to high fluid temperature? Get the codes and find out what is turning on the light. There are many possible trans problems that will turn on the light.
 

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^^^^ how do you know the check trans light is on due to high fluid temperature? Get the codes and find out what is turning on the light. There are many possible trans problems that will turn on the light.
Finally pulled the codes today....none were there.
During the past few weeks the frequency of the check trans coming on the evic has increased. I drive on avg over 150 miles a day and this morning it came on 30 miles out with a 60 degree ambient temp.
Drove 350 miles yesterday with the check trans coming in early in that trip as I had done some running around the city prior to departure and dealt with it coming on every 10 minutes for 4.5 hrs.

I need some ideas to correct this problem.
 

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Does anyone know if you can read tranny temp with an AGT ODB2 code reader(Advanced German Technology). It not a horrific expensive one, I got it today and tried it a bit. Not sure what it is capable of.



Ignore this, I answered my own question by goofing around with it. It's just a basic ODB2 reader I can check errors, delete them from eec memory, check readiness states of various things. If mine was a 2002 or newer, read the VIN number.
 
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