In this issue of Keep Those Trannys Rolling, we are going to take a look at a 2020 Ford F150 XLT, equipped with a 2.7L ECO-BOOST engine and a 10R80 transmission, that was experiencing erratic transmission operation and a running hot condition at times.
We first became aware of this vehicle’s running hot condition when our local parts delivery person dropped off a load of parts to us. During the parts check-in process, our parts person noticed a puddle underneath the parts delivery truck and pointed it out to the driver. The driver acknowledged the leak and commented that the transmission had been acting weird for the last couple of weeks. After further discussion with the driver, we learned that the driver had been experiencing erratic transmission operation, a burning-type smell, and a puddle of transmission fluid on the ground after every delivery stop. We contacted the parts warehouse manager to inform him of their driver’s concerns. According to the manager, the driver had reported having problems with the transmission operation, but they were unable to schedule an appointment with their local Ford Service Department. The next available appointment was four weeks away. After a brief discussion with the manager, we offered to take a look at the transmission.
Preliminary Inspection:
After giving the delivery driver a ride back to the parts warehouse, we lifted the vehicle into the air to perform a preliminary inspection. During the inspection, we found the entire vehicle’s underside was covered with transmission fluid. We steam-cleaned the underside of the vehicle, checked and refilled the transmission with the correct fluid, and drove the vehicle on the rack to see if we could locate the source of the leak. After several minutes of driving the vehicle on the rack, we could not find the source of the transmission leak. It was apparent that we would have to drive the vehicle on the road to duplicate and diagnose the driver’s concerns.
Duplicate to Diagnose:
After realizing that we would have to drive the vehicle to duplicate the leak, we connected our scan tool to the vehicle data link connector (DLC) and checked the computer system for codes. There were no codes set or pending in any of the modules, but codes P0218 (over-temp) and P0741 (tcc perf) were set in the Powertrain Control Module (PCM) memory. We cleared all stored, pending, and memory codes from the PCM and headed out for our initial test drive. Prior to our road test, we set up our scan tool to monitor the transmission fluid temperature (TFT), solenoid commands, torque converter slip, and engine coolant temperature. With our scanner ready to go, we headed out for our initial road test. During the road test, we drove around town at speeds ranging from 5 mph to 45 mph. We parked several times and allowed the vehicle to sit idling for a few minutes. We drove the vehicle on the freeway at speeds up to 65 MPH. 
We tried to duplicate the driving that the parts delivery person would encounter during his daily routine. After driving the vehicle most of the day, we noticed the transmission fluid temperature would climb to around 240°-250° while the engine coolant temperature remained steady at 198F degrees. We monitored TCC operation during our drives and noticed that TCC slip was all over the place, ranging from 10-20 RPM to 70-80 RPM of slip, depending on engine load. With erratic TCC operation and transmission fluid temperature steadily increasing, it was obvious that we were experiencing a TCC-related concern. With the erratic transmission operation and high-temperature concerns duplicated, it was time to head back to the shop to see if we could diagnose these concerns.
Back at The Shop:
Back at the shop, we lifted the vehicle to check for leaks. There were obvious signs of fluid coming out of the transmission vent. We inspected the transmission cooling system, and everything was okay there. We checked the transmission cooler flow & verified it was proper. We checked the temperature drop across the cooler and found a 30° drop across the cooler. We compared the scanner’s TFT temperature to a thermal gun, which indicated that the TFT reading was accurate. We removed the transmission pan and found a slight amount of clutch debris in the pan. We removed the valve body and air-checked the clutch components with 35psi of regulated air pressure. Each clutch air checked with no leaks. We disassembled and inspected the valve body. We vacuum-checked the TCC control valve, TCC regulator valve, TCC priority valve, converter feed blow-off valve, TCC damper valve, and bores, checking for wear. We found that the TCC damper valve & bore were excessively worn. 
The TCC damper valve dampens the pulses of the TCC control fluid going to the TCC control valve. It is reasonable to conclude that the worn TCC damper valve and bore were causing the erratic TCC operation and running hot condition. With a worn TCC damper valve and bore, it was time to replace the valve body.
Houston, We Have a Problem:
After confirming that the TCC damper valve and bore were worn, it was time to replace the valve body. We contacted our local Ford Parts department to order a torque converter and valve body assembly. According to our local Ford Parts department, the torque converter would arrive the next day, but the valve body assembly was on national back-order, with no delivery date listed. This was going to be a problem. We contacted our aftermarket parts suppliers and inquired about 10R80 valve body repair kits. We were able to purchase an aftermarket “drop-in” TCC damper valve kit from our local parts suppliers. We ordered the TCC damper kit from our local parts supplier and the torque converter from our local Ford Parts Department. Parts arrived the following morning.
Parts in Hand:
The torque converter and TCC damper valve kit arrived the very next morning. The TCC damper valve kit was pretty basic: It included an o-ringed sleeve, piston, spring, and plug (Figure 1). I installed the TCC damper valve kit into the lower valve body (Figure 2). During the valve body repair, we removed the transmission assembly and replaced the torque converter. With the transmission removed, we flushed the cooling system and installed the valve body assembly, new OEM filter, and pan onto the transmission case. We installed the transmission into the vehicle and filled the transmission with fluid. 
We started the vehicle, momentarily engaged each gear, and rechecked the transmission fluid level. We brought the transmission fluid level up to the proper level and checked for leaks. There were no leaks. With the TCC damper valve repaired and the torque converter replaced, it was time to head out for our final test drive.
Final Test Drive:
With the scan tool connected to the DLC, it was time to head out for our final test drive. We headed out for our final test drive with the scan tool monitoring the TFT operation and TCC slip. We drove the vehicle through city streets, parking lots, and onto the freeway. During the test drive, the TCC slip remained steady at 10-20 RPM while the transmission fluid temperature was steady at 190°. We continued to drive the vehicle with no change to the TCC slip or TFT operation. With the TCC slip and TFT steady, it looked like we’ve got this one fixed. We contacted the parts warehouse manager and made plans to have the vehicle delivered to their location.
With a better understanding of how the TCC damper valve controls TCC application, you should have no problem Keeping Those Trannys Rolling down the road.
