Join Date: Dec 2014
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Neither bling nor illogical...
Pros for the cooler line location:
You will only see the full range of temperature at the front cooler line.
Normal temps when monitored at the front cooler line would fall in the range of about 140° F to 280° F
While watching the temp at the front cooler line you can instantly see the temp climb if you are pulling a heavy load. You can also see the temp fall almost instantly when you back off the throttle and you can also tell that the converter clutch was COMMANDED to lock, because the temp will drop instantly even when under heavy load when the converter clutch is COMMANDED to lock up.
The cons of this location, and one of the reasons I prefer the sender in the pan is because if we are monitoring the gauge this close your eyes are not on the road. This is a very active gauge when the sender is in the front cooler line. The sudden and extreme range of temps you will see may make one nervous even though they are well within the norm at this location.
Just the opposite is true if you install the gauge in one of the pressure ports of the transmission case. The fluid at any of these test ports is stagnant oil, once the oil gets to the test port it is at a dead end and is no longer circulating. At one of these locations we will really be reading the temp of the transmission case. At these locations it will take the longest to get a reading, and by the time you see a reading above 200° the converter temp was probably around 250° - 270° for quite some time because it takes a while for the heat to radiate into the case and once the fluid cools it will also take a while for the case temp to drop, back to that radiation thing again. At this location expect to see normal temps range from about 140° to 190° - if the temperature reaches above 200° I would find a place to pull over.
Pros for the pressure test port location would be ease of install and multiple locations to use.
Cons for these locations would be slow gauge reaction time and also we need to make sure the sensing tip of the sensor is not too long and bottoms out before you have the sensor tight. WE DO NOT RECOMMEND THESE LOCATIONS
We like to install the temp sender in the trans pan. The gauge will react quick enough to save the trans form overheating and yet the gauge won’t be so active that it would make one nervous about the temp extremes. The normal temp range you would see will be about 140° to 200°. If the trans temp gets above 200° F we would want to get the engine rpm above 1500, I will explain why. Fluid that is cold does not move very quickly through small passages, like the small passages in the valve body. Fluid that is too hot is hard to pump because it is too thin.
Fluid at 230° does not hurt the seals, gaskets, or clutches, but, because it is so thin it is hard for the pump to maintain enough flow so the valve body can maintain enough pressure in all the circuits. At approximately 200° in the trans pan even a good pump will have a hard time flowing enough fluid to satisfy all the circuits when the pump rpm (same as engine rpm) is below about 1,300 rpm. If the pump can’t maintain the volume of oil and the pressure regulator valve cannot maintain good pressure, the clutches and bands will slip. The cooler flow and pressure will also be lower and this will escalate the heating problem. This can easily be seen on the transmission dyno where we can monitor trans temp, clutch pressures, cooler pressures and volumes. Even with hot fluid above 200° these pressures and volumes come back to normal when we bring the rpm close to 1,500.
With 4.10 gears this is not really a problem because the engine rpm will not be around 1,500, but, with 3.54 gears you can easily be at 60 mph or lower with the converter locked up and the engine rpm could be around 1,500. All depending on tire diameter, of course.
For the above reasons alone we do not like to get the converter stall too low, lets say someone wants an extremely low stall converter and they are going to do a lot of snow plowing, the engine and customer may like the low rpm but if you are working things especially with the converter clutch unlocked at low rpm the pressure and cooler flow may suffer.
Hope this clears things up for you as far as sender locations are concerned
If you have any questions just call Dave @ 563-778-2719
Good advice for the average driver not trying to diagnose a transmission problem.
04.5 Qsb Synergy long arm-Carli 3”linear spring Deaver race pak w/Thuren shackles 2.5” stage 4 short body shocks large bypass tubes rear- truss