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transmission temperature

What is the normal operating temperature range for the 4R100 auto trans ? With & Without towing ?

99 Ford F250/7.3PS/3.73 AX/4R100,W/MERCONV/57K miles

& Tow a 10K 5th Wheel.

Current experience: 150 degrees without towing around town,
165-175 degrees towing around town, 150 degrees towing on highway at 65 mph with air temp at 85 degrees.

Trying to determine if I should switch to synthetic trans fluid before traveling west to the mountain states.
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scott
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Those are about the same temps i get with my 2001 4R100, i was towing a 20 foot boat in 97 degree weather the other day and i seen it get up to 175.... other than that it will stay under 160 running around town, and stay under 150, on freeway driving... 65-80 MPH.... Im going to switch to AMSOIL ATF, in 5k miles... I would say switching to a synthetic would be a good idea.
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An authorative source has told me the Ford transmissions run from 60 to 90 degrees over ambient with the 4R100 being at the high end. Also, the general knowledge is to not worry until the trans fluid temperature exceeds 220 degrees. Word on another site from a cooling design engineer claims the modern "dino" fluids are designed for up to 250 degrees. Therefore, I would think you have nothing to worry about. For what it is worth, here is a table I picked up. I think the left column is highest temperature and the right is when to change fluid. However, I recommend more frequent fluid changes than those at the lower temps. IE, not more than 20,000 before change if you tow. Probably less if you tow more than 30 percent of the time.

"TEMP(F) / MILES

175 / 100,000
195 / 50,000
215 / 25,000
235 / 12,500
255 / 6,250
275 / 3,000
295 / 1,500
315 / 750

Above 300, Clutches and Seals burn and transmission metals warp and
distort!!!"

And the last bit of info I have is synthetics will add about 50 degrees to the tolerance.
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'01 F250 Lariat; SWB; Shell; K&N Air Filter; BD - Brake, Autoloc, Transmission, Aux. Trans Cooler; Gauges - Boost, EGT, Trans Temp. Used to tow a 30 ft. Airstream Travel Trailer. (8000lbs)
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Good post Dale - absolutely - the cooler it runs, the longer it lasts.

Hey Scott - just wondering where your temperature sender is located? The temps you are seeing are nice and cool - I am assuming that you are pulling your temps from the pan.
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'95 12V 2WD
312HP/720 ft.lbs.

Pump,Injectors,Plate,Springs,Converter,
Transmission,Brake,Manifold,Exhaust,Intake,Gauges.
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Yes Dean, the temp probe is in the transmission pan.

Could it be harmful to the transmission if it runs too cool ?

I'm concerned that if I switch to synthetic atf, it might run too cool ! Is that possible ?
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scott
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Hi -

I don't think that there really is a 'minimum' temperature that the transmission should run below. Our test equipment pre-heats the transmission fluid to 140F to more closely simulate the operating conditions and temperatures of the oil during normal operation. The viscosity of the fluid changes a bit from cold to warm.

The transmission cooler (the OEM cooler attached to the bottom of the rad) is actually a fluid 'warmer' as well - the coolant temperature normally runs about 180-190ish - the hot coolant warms up the transmission fluid a bit. This is handy in the northern climes to get the tranny fluid up to temperature on those frosty days. The cooler/warmer is not 100% efficient so the transmission fluid generally won't be exactly the same temp as the coolant, but under normal driving conditions we see it operate around 140-150ish.

The more time you spend in 'fluid-coupling' mode, (converter un-locked) the quicker the fluid temperature will rise. The shearing of the fluid inside the torque converter creates alot of heat. If you live (and drive mostly in) the desert (are not concerned about low temps), you could possibly re-route the transmission fluid lines to by-pass the OEM radiator, and run a large multi-pass transmission cooler. This way, the fluid won't pick-up any heat from the coolant in the radiator.

I wouldn't recommend this if you are a full-time RV'er and traveling across the continent - you can end up in very different temperature zones that may take advantage of the fluid warm-up feature.

Hope this helps -
__________________
'95 12V 2WD
312HP/720 ft.lbs.

Pump,Injectors,Plate,Springs,Converter,
Transmission,Brake,Manifold,Exhaust,Intake,Gauges.
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Ford bypasses the coolers to warm the transmission fluid. Located on the right side and just in front of the tranny is a bypass valve. This valve is controlled by pressure. When the fluid is cooler, the pressure is lower and the valve routes the fluid back into the tranny at or near the return line. As the fluid warms the pressure increases and the valve will then route fluid to the coolers. If this valve malfunctions you can get into an over heating condition. Likewise, if the flow is obstructed through the lines and coolers, overheating can occur.

The OTW cooler in the bottom of the radiator is seldom at 190 degrees. Hot coolant returns to the top of the radiator and by the time it gets down to where the OTW tranny cooler is, it is closer to ambient temperature than 190.

Dale
__________________
'01 F250 Lariat; SWB; Shell; K&N Air Filter; BD - Brake, Autoloc, Transmission, Aux. Trans Cooler; Gauges - Boost, EGT, Trans Temp. Used to tow a 30 ft. Airstream Travel Trailer. (8000lbs)
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Quote:
Hot coolant returns to the top of the radiator and by the time it gets down to where the OTW tranny cooler is, it is closer to ambient temperature than 190.
Hmmm.... well, I can agree that the hot coolant in the radiator is going to cool off a bit as it is processed through the core, but I highly doubt it would be that close to 'ambient' air temp.

If the hot coolant is (for example) 200degreesF at the top of the rad, (thermostat is open) the 'cooled' coolant at the bottom of the rad would be about 150-160ish degreesF. The drop in coolant temp really depends on the outside air temp, (and the size/depth of the core) - realistically you are only going to see a drop of about 40-50 degrees.

With an OTW cooler, the 'ambient' temperature would be the temperature of the coolant (The cooler of the two mediums). The OTW cooler can only cool down to its 'ambient' level. The coldest point on the OEM cooler is probably about 150ish degrees. If you had an amazing cooler that was 100% efficient, you could cool the transmission fluid to about 150ish, but that is about as low as it would go.

On an OTA or ATA cooler, the outside air temperature would be 'ambient' - like a radiator, or an air-charge cooler.

My 2 cents.
__________________
'95 12V 2WD
312HP/720 ft.lbs.

Pump,Injectors,Plate,Springs,Converter,
Transmission,Brake,Manifold,Exhaust,Intake,Gauges.
Reply With Quote

Quote:
If the hot coolant is (for example) 200degreesF at the top of the rad, (thermostat is open) the 'cooled' coolant at the bottom of the rad would be about 150-160ish degreesF. The drop in coolant temp really depends on the outside air temp, (and the size/depth of the core) - realistically you are only going to see a drop of about 40-50 degrees.
I would agree it is somewhere in the 100 to 140 range, again depending on ambient. As a test, one could place their hand on the radiator hose supplying coolant to the engine, carefully of course. This will tell you it is considerably cooler than the hose returning from the engine.

Dale
__________________
'01 F250 Lariat; SWB; Shell; K&N Air Filter; BD - Brake, Autoloc, Transmission, Aux. Trans Cooler; Gauges - Boost, EGT, Trans Temp. Used to tow a 30 ft. Airstream Travel Trailer. (8000lbs)
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Thanks for all the good info....appreciate it!
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scott
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