Transmission overheating!!

[slinky]

Ok so i had my 4t60e rebuilt and it was rebuilt incorrectly causing everything to burn up even with a external cooler. So i took it to a reputable shop and had them rebuild it with hardened parts, trango shift correction kit, Torque convertor lockup and shimmed accumulators ect. I was assured by someone who rebuilt over 400 4t60e's that it was perfect,

It shifts and drives perfect now but still over heats. i know this because i installed a temp sensor in one of the lines. It seems like as soon as it starts going up in temp it just wont stop.

I should mention that i rewired the trans to the obd2 harness i installed in my obd1.5 engine if that would change anything.

I have the external cooler mounted to the front of the radiator by the way.
He also pressure tested the lines to check for leaks ect.

Anyone know why its overheating when it was rebuilt perfect?

Temps are rangeing from 180f-240f normal operating

[55trucker]

It sounds as tho there is possibly low or no fluid flow past the one way check valve in the line that supplies the rad tank cooler. There is a one way check valve in the supply side (inside the trans case) that prevents reverse flow back thru the solenoid actuated Conv clutch apply circuit. One way to verify if fluid IS flowing thru the cooler is to simply feel the temp of both lines when trans is warm to hot. The return line should be cooler than the supply side.
When you installed the external cooler did you plumb it in series with the tank or bypass the rad tank cooler? Bypass is not the preferred method if so, it's better to make use of both coolers.
Also, is the external a low pressure drop cooler?

[slinky]

i will check the temp on the two lines tomarrow, it runs through the rad than through the cooler than back to the trans, i was told it could be the fluid pressure

[torq455]

Did you put the temp sensor in the cooler lines, or in the bottom of the trans? The converter creates a lot of heat and that fluid goes directly to the tranny cooler. If you put the sensor in the supply line, that would explain your high temps.

[slinky]

The lines are in the correct flowing pattern and yes it is in the lines and not in the pan

[3400-95-Modified]

first things first, Remove the lines going to the stock cooler, its not providing much cooling if your engine is running at 200*... Its simply raising the trans temp to that level. I only have the largest external cooler you can install on my car and on the highway I'll run between 170-180* and I have a very high stall converter and my pump pressure is up there.

Also have you checked to see what the temp is IN the trans? By using the stock sensor and data logging it? thats all I'm using.

The return line IIRC is the horizontal inlet on the trans, the vertical one is the outlet/pressure just for reference.

I could have that backwards, I can't remember or find it anywhere, best way to test is just have the lines off and in a bucket and have someone star it for 1 second to see what line is providing the flow.

[Azrael]

I'll see 200-220F in stop and go traffic on a hot day with a 14k lb cooler. My service manual says that the fluid temp isn't considered excessive until it goes above 266F(130C).

[bob442]

After 240 a trans is usually cooked. How'd your cooler flow? Ideal flow is 1.5-2 liters in 15 seconds of run time, to test this simply jack the car up, disconnect the horizontal line and put it in a. Clear 2l+ container, and have someone run the car as you count to 15 seconds. Your coolers could simply be plugged, also if you have your temp sensor on the pressure you will see those higher numbers.