Solved New 5R55S. The transmission slips.

[Christopher Runnells]

I have a 2008 Ford Explorer 6 cyl. 4.0L 4WD. Nine months ago I installed on my own a rebuilt 5R55S transmission. It ran fine until a few months ago when it started slipping intermittently. Here are the key points:

• It slips mostly when it's warm and has been driven for a bit. Very rarely will it happen when the motor is cold and just started.
• The slipping usually occurs after the car has been sitting idling for a few minutes, doesn't matter if it's in Park or if my foot is on the brake for a few minutes in stopped traffic. Also happens when I've parked the car for a few minutes and shut off the motor (like running quick into a convenience store). When I resume driving, the engagement takes a few seconds.
• Another scenario: after driving at highway speeds, I slow down and stop at a light or stop sign, resume driving and it won't engage in the same manner.
• When it finally engages and I can accelerate, it doesn't want to shift into higher gears. I have to let off the gas for a few seconds and try again, and then it will engage. Sometimes if I shift the transmission from Drive to 3 and then back to Drive, that seems to force it to engage and behave normally.
• The symptoms only seem to happen once or twice per driving session. The problem usually corrects, and I can continue driving for a while and it won't slip anymore.
• There is no leakage
• I have checked the fluid level 3 times. The fluid level is correct, and no burnt fluid smells.
• There is no engine light, no wrench light, no codes.
• I have reset the computer a few times (disconnect the battery for 15 minutes and connect a wire between both battery cables). This seems to correct the problem briefly, but the symptoms come back.
• The problem has not worsened over the course of a few months. Just the same behavior.

I appreciate any help or advice I can get. I’m hoping it’s something minor that won’t require dropping the tranny again. I purchased it from a reputable parts dealer and installed myself.

 

[BrooklynBay]

Welcome to this forum! What kind of transmission fluid did you use? Did you check the fluid level when it warms up?

 

[Christopher Runnells]

Welcome to this forum! What kind of transmission fluid did you use? Did you check the fluid level when it warms up?

I used STP Mercon V, the transmission was warmed up, level, and idling in park while checking the fluid level. I used that same fluid on my previous transmission on the same car (TC blew out at 110k miles).

 

[Christopher Runnells]

Update: I dropped the pan, replaced the solenoid pack, and checked the valve body gasket. Everything seemed fine, there were no metal shavings in the pan and the fluid looked/smelled fine. I reset the computer and the car drove fine for about 100 miles and then the symptoms came back.

Could this be a sensor problem? Still no codes being thrown.

I've noticed that the slippage occurs in every gear but mostly in the lower gears. If I let off the gas and/or shift from D to 3 and back to D, that seems to force the transmission into gear. The slipping is still sporadic, sometimes the transmission shifts perfectly.

I'm just about at my wits end and developing a healthy hatred for Explorers. Any help would be appreciated.

 

[JK080]

The linkage adjustment on these things can be problematic, if its off just a little bit it can cause all kinds of issue like this.

Put the shifter in park or neutral then release the cable connection at the transmission and make sure the transmission linkage is completely in park or neutral, then double check the shifter position inside to be sure its still correct.
Release the adjustment slide on the cable and connect the cable back on the transmission linkage and lock the adjustment slide back down. You may be able to tell if it is in a different location from when you started if you make a mental note of where it was before you release it.

Other things that come to mind is a problem with a valve in the pump that likes to stick, hopefully whoever built it used a better designed valve that is available. Maybe some issues with the valve body like worn bores or hanging valves.

This is the downside of buying a transmission and installing it yourself, if something is wrong or if issues arise your only options are to diagnose it yourself and repair it or pull it out and have to ship it out for another one and have to deal with warranty and liability.

If one of our transmissions have issues they simply take it back to us and we handle it.

 

[Christopher Runnells]

The linkage adjustment on these things can be problematic, if its off just a little bit it can cause all kinds of issue like this.

Put the shifter in park or neutral then release the cable connection at the transmission and make sure the transmission linkage is completely in park or neutral, then double check the shifter position inside to be sure its still correct.
Release the adjustment slide on the cable and connect the cable back on the transmission linkage and lock the adjustment slide back down. You may be able to tell if it is in a different location from when you started if you make a mental note of where it was before you release it.

Other things that come to mind is a problem with a valve in the pump that likes to stick, hopefully whoever built it used a better designed valve that is available. Maybe some issues with the valve body like worn bores or hanging valves.

This is the downside of buying a transmission and installing it yourself, if something is wrong or if issues arise your only options are to diagnose it yourself and repair it or pull it out and have to ship it out for another one and have to deal with warranty and liability.

If one of our transmissions have issues they simply take it back to us and we handle it.

I did as you suggested and adjusted the linkage. This seems to have fixed it! I've driven over 100 miles and haven't had any issues. Thank you so much for your help! If you hadn't have commented, I probably wouldn't have thought about checking the linkage.

 

[BrooklynBay]

Thanks for the update. Your thread is now marked as solved.