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C4 running temp

latrucker

Contributor
Sr. Member
Joined
Jul 19, 2010
Messages
614
I have a stout 351W with a C4 from Broader Performance, 4:11s on 33" tires. One cooler mounted under the bronco around the passenger seat area. It is a Derale atomic cooler with a 180degree thermostat and electric fan. After cruising for 15 minutes or so driving it very easy the fan stays on all the time which tells me it is running at least 180 all the time. Is this normal?
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,835
Where is the temp switch located at?
Typical temp switches have a hysteresis. Turns on at 180, off at 160 or something like that.

If the temp sensor is on the convertor out line the trans operating temp could be much less then 180 but the fan will stay on.

Trans coolers mounted under the vehicle are generally no where near as efficient as mounted in front. Its difficult to figure how the air moves under there. Lots of turbulence. Decent chance that the fan might be fighting the natural airflow direction. Is that the only cooler for the transmission?
 
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latrucker

latrucker

Contributor
Sr. Member
Joined
Jul 19, 2010
Messages
614
Yes, only one cooler. Comes directly out the trans into the cooler temp switch. Thinking about running a second cooler in front of the radiator but don't want to if not necessary. Is 180 on the high side?
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
That fluid temp coming right out of the tranny is the hottest fluid coming right out of the converter. In that placement your fan will always be on at 180 F Most of the fluid will be closer to 200F or higher under load. You need to use pan temperature to be accurate to what the tranny sees. Knowing what the tranny pan temperature is, is more important than whats going into the cooler. What the temperature is coming out the cooler is more important than what is going into the tranny cooler. Its whats coming out of the cooler that cools the tranny. The temperature of the oil in the pan is what the tranny runs off of. I personally would move the temperature switch to the out put of the cooler but the pan temp would work too.
 

KyleQ

Bronco Guru
Joined
Apr 24, 2008
Messages
5,480
Trans temp typically mirrors water temp as those are typically combined in OE applications. The higher the temp goes the shorter the lifespan of the fluid.
 

bbow

Bronco Guru
Joined
Apr 18, 2012
Messages
1,160
Loc.
Ozark, Alabama
The highest I have seen my trans temp go was this weekend at Cades Cove Ride. Engine Temp was about 210 and Trans Temp was 170. Deep sump pan with sensor in pan and trans cooler in front of radiator.
 

Eoth

Bronco Guru
Joined
Mar 10, 2004
Messages
1,677
175 is normal temp and your fluid will be happy and will last 100,000 miles. As a rule of thumb, every 20 degree increase in operating temperature above 175 degrees cuts the life of the fluid in half. At 195 degrees F., for instance, fluid life is reduced to 50,000 miles. At 220 degrees, which is commonly encountered in many transmissions, the fluid is only good for about 25,000 miles. At 240 degrees F, the fluid won't go much over 10,000 miles. Add another 20 degrees, and life expectancy drops to 5,000 miles. Go to 295 or 300 degrees F., and 1,000 to 1,500 miles is about all you'll get before the transmission burns up. Bad fluid = bad trans.... At 250 degs damage to seals will occur even if your fluid is good.
 
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