Keep Those Trannys Rolling - July - 2023

10R80 Slips Into The Drink

In this issue of Keep Those Trannys Rolling, we are going to take a look at a 2020 Ford F150 XL 4X4 equipped with a 5.0L engine, a 10R80 transmission, and “Monster Mudder” tires that was experiencing delayed engagements and slipping on acceleration from a stop at times. I first became aware of this concern when my friend Ben invited me and a couple of friends to join him and his family at a local lake for a day of water skiing, jet skiing, and BBQing. After having a way-too-much of a fun-filled day at the lake (which should have been illegal), it was time to pack up the truck and head home. After loading up the truck, Ben backed his truck and trailer down the ramp so that he could load his ski boat onto the trailer. With the ski boat secured to the trailer, it was time to head home.

Slipping into the Drink

After we secured the ski boat to the trailer, Ben jumped back into his truck, started the vehicle, engaged the transmission into “D,” and released the parking brake. As Ben released his foot from the brake pedal and accelerated, the truck and trailer began to roll back into the lake. Luckily, Ben’s F150 truck had Monster Mudder tires on it, which allowed the truck to float. Ben’s F150, the trailer, and the ski boat were all floating next to the dock. Needless to say, things were getting pretty exciting. While the F150, trailer, and boat floated around the dock area and everybody was running around in a panic, Ben casually walked back up the ramp to see if he could talk one of the other boaters with a truck into helping us recover his F150, trailer and ski boat from the lake.

F150 Rescue

Within a few minutes, Ben was heading back down the ramp with a tow strap in hand and a truck following him. After attaching the tow strap to the recovering truck, Ben swam out to his truck with the tow strap and attached it to the front of his truck. Ben then climbed into his F150, as it was floating in the lake, and signaled the other truck that he was ready. The recovering truck began pulling Ben’s F150, trailer and ski boat back towards the ramp. Once the F150, trailer and ski boat made it back to the ramp, Ben started his truck and attempted to accelerate. Unfortunately, there was no engagement. The recovering truck pulled Ben’s F150, trailer and ski boat back to the camping area so we could take a look at it. Thank God for Boaters with trucks.

Back at the Camping Area

With Ben’s F150, trailer and ski boat safe at the camping area, it was time to take a closer look at Ben’s F150. We crawled underneath the vehicle (thank god for big tires) and looked at the drivetrain. We inspected the drivelines, transfer case and electrical connections. We rocked the vehicle back and forth in Park and verified that the transfer case and transmission park mechanism were working. It was obvious that the “no engagement” concern was transmission related. After a brief conversation with Ben, I discovered that this was not the first time Ben’s F150 had a “no engagement” concern. According to Ben, his F150 has been having a problem for a while now. Ben said he has been to the local Ford dealership several times, but the dealer could not duplicate the “no engagement” and “slip-on-acceleration” concerns. Ben says the problem is intermittent, and eventually (after shutting off & restarting the engine several times), the transmission would engage and be able to drive. So, Ben started and shut off the engine several times, and eventually, the transmission engaged into “DRIVE.” With the transmission working, we packed up the camp and headed home.

First Thing Monday

Morning First thing Monday morning, I contacted Ben to thank him and his family for inviting us to the lake. During my conversation with Ben, I asked him what was going on with his truck. Ben said that the dealership was not able to duplicate his “no engagement” concern, but they had indicated that it was probably a valve body problem. Unfortunately, the valve body was not readily available. Ben said that he loves his new truck. It only had 20k miles on it, and he did not want to trade it in for another one. I explained to Ben that the dealership must duplicate and diagnose the concern before they can repair it. If they cannot duplicate the problem, they cannot diagnose it or make a repair under warranty. I told Ben that I would contact the dealership to see if we could help him.

Using Your Dealership Contacts

After getting all the information from Ben, I contacted our local Ford Dealership Service Department and talked to Charlie, the service manager. I discussed Ben’s concerns with him, and he said he would give me a call back after he looked into it. A few hours later, Charlie called me back to discuss Ben’s concerns. Charlie verified that Ben’s F150 had been to their service department several times regarding a delayed engagement and slip-on-acceleration concern. According to the service file, the problem could not be duplicated. Charlie said the vehicle was getting close to being eligible for a “buy-back” under the “lemon law.” I explained to Charlie that Ben loves his F150. It matches his ski boat and trailer, and he was not interested in trading it in. Charlie told me that if we could duplicate and diagnose the problem, he would gladly help us repair it under warranty. After my conversation with Charlie, I contacted Ben to discuss a possible resolution. Ben agreed to drop off his F150 the next morning so we could take another look at it.

The Next Morning

The next morning, I arrived at the shop to find Ben waiting at the gate to drop off his truck. Ben said the delayed engagement concern had happened more frequently and hoped we could duplicate the concern. I was already familiar with the vehicle, having crawled underneath its last weekend, so I didn’t need to do a walk-around inspection. I did, however, open the hood and inspected the engine compartment wiring, connections, battery, and fluid levels. Everything looked good. I connected our scan tool to the data link connector (DLC) and scanned the vehicle for codes. There were no codes in any of the modules. I connected our pressure gauge to the line pressure port and prepared for our initial test drive.

Initial Test Drive

With our scan tool connected to the DLC, I set up the scan tool to monitor the line pressure control system PIDS.

The scan tool was set up to monitor:
LINEDSD (Desired line pressure)
LPC (actual line pressure)
LPC_AMP (line pressure control solenoid amps)
LPC-F (line pressure control fault)
LOAD (calculated engine load)

With the scan tool set up to monitor the line pressure control system PIDS and the pressure gauge connected to the line pressure tap, it was time to see if I could duplicate the delayed engagement or slip-on-acceleration concern.

Duplicate to Diagnose:

With the scan tool and pressure gauge connected to the vehicle, I headed out for our initial test drive. I drove the vehicle through city streets and then out on the highway. The transmission worked perfectly. I drove through stop-and-go traffic for over an hour with no problems at all. With Ben’s permission, I drove the vehicle home that evening and around town the next day. Everything seemed to be okay. After driving around the area for two days with absolutely no problems whatsoever, I pulled into our local gas station to fill her up. After filling up the truck and getting my Big Gulp, I started the vehicle, dropped it into gear, and, low and behold, “no engagement” forward or reverse. I looked at the pressure gauge. The pressure gauge indicated less than 10 psi of pressure. I checked the line pressure control system PIDS on my scanner. LINEDSD (desired press) indicated 110 psi. and would change with throttle movement. LPC (actual press) indicated 8psi. and gradually climbed to around 12 psi. with throttle movement. LPC_AMP (l pcs amps) would change with throttle movement. LOAD (cal eng load) was within specification and would change with throttle movement. All indications pointed to a low-pressure problem. After shutting the engine off and restarting it several times, I was able to engage the transmission into gear and headed back to the shop.

Back at the Shop

With the vehicle back at the shop and all indications were that we were looking at a low-pressure problem, we removed the pan to inspect the fluid condition and check for debris. Surprisingly, the fluid was clean and red, with no debris floating around. I removed the filter and inspected it. The filter was clean, with no signs of debris in the filter element. I removed the valve body and air-checked the clutch components with 40 psi of regulated air pressure. Each of the clutches air checked with no signs of any leaks. I cleaned the valve body and checked it for any signs of wear or debris. The valve body visually looked good. I vacuum-checked the pressure regulator valve and found the valve, bore & end plug were leaking excessively (less than 14″ of vacuum, Figure 1). I continued vacuum-checking the remainder of the valve body and found no other concerns. With a worn pressure regulator valve and end plug (Figure 2), it was time to replace the valve body with a new valve body from Ford. With a firm diagnosis, I contacted Charlie in the Service Department and explained what I had found. After a brief conversation with Charlie, he agreed that I was heading in the right direction, but unfortunately, valve body assemblies have been on backorder for several months with no expected delivery date.

Charlie asked if there was anything I could do to get this vehicle back on the road. I told Charlie that I would look into it and get back to him shortly. After a few hours of research and phone calls, I located an aftermarket pressure regulator valve repair kit. I ordered the kit and expected it to arrive the next morning. With a solution to the problem, I contacted Charlie at the Ford Service Department to discuss what I had found. After speaking with Charlie, he gave us the okay to go ahead and repair the valve body.

Parts Arrive, Fix in Hand

The next morning, the repair kit arrived, which was pretty basic. Just a valve, spring, end plug and basic directions (Figure 3). I installed the kit components and vacuum-checked the pressure regulator valve and bore. The pressure regulator valve & bore vacuum checked at over 18” of vacuum, indicating that the valve, bore, and end plug were sealing properly.

With the pressure regulator valve repaired, it was time to put this transmission back together and recheck its operation. I installed the valve body onto the transmission case and installed an OEM filter. I refilled the transmission, started the vehicle and allowed the transmission to reach normal operating temperature, and then rechecked the fluid level. I inspected the underside of the vehicle for leaks. There were none. It was time to head out for the final test drive to check the transmission operation.

Final Two-Day Test Drive

I headed out for our final test drive, and the transmission seemed to work perfectly. With Ben’s permission, I held onto the vehicle for two more days, driving it as if it was my own. The transmission worked great. I contacted Ben and discussed the repair process. Ben was happy his vehicle was finally fixed and that he would not have to worry about swimming to save his truck anymore. I contacted Charlie at the Ford Service Department to let him know that the truck was fixed and returned back to Ben. Charlie was happy that Ben’s truck was repaired and thanked us for our help.

Well, there you have it. I survived a way-too-much-fun weekend and was able to repair a friend’s truck and save it from the auction. With a little bit of help from your friends, local dealership contacts, and aftermarket suppliers, you, too, should have no problem keeping those trannys rolling down the road and out of the drink.