5R55W - intermittent no movement

[Guk22]

2003 Mountaineer V8 AWD 185K miles. Rebuilt trans about 2 1/2 years and 40K miles ago due to the dreaded flashing OD / servo bores. Truck is in pretty good shape, like to keep it going a bit longer without a huge investment.

-The problem, sometimes I get in (hot of cold) and drive anywhere... no issues, shifts perfect, no codes, leaks or other obvious problems.
-Other times I get in and it simply will not move! Doesn't matter if it is hot or cold, sitting flat, on an incline, sunny or snowing.

I have tried a fluid and filter change, no difference. The fluid and filter that came out appeared new and I'm sure this was a waste on money. The only thing I can come up with is the "Transmission Pump Flow Control Valve" may be sticking causing this. I can change this $40 part. I would rather not spend the time and effort if this is only my best guess. I am hoping to get some input from the trans experts here.

 

[imp]

2003 Mountaineer V8 AWD 185K miles. Rebuilt trans about 2 1/2 years and 40K miles ago due to the dreaded flashing OD / servo bores. Truck is in pretty good shape, like to keep it going a bit longer without a huge investment.

-The problem, sometimes I get in (hot of cold) and drive anywhere... no issues, shifts perfect, no codes, leaks or other obvious problems.
-Other times I get in and it simply will not move! Doesn't matter if it is hot or cold, sitting flat, on an incline, sunny or snowing.

I have tried a fluid and filter change, no difference. The fluid and filter that came out appeared new and I'm sure this was a waste on money. The only thing I can come up with is the "Transmission Pump Flow Control Valve" may be sticking causing this. I can change this $40 part. I would rather not spend the time and effort if this is only my best guess. I am hoping to get some input from the trans experts here.

Have you checked for trouble codes? imp

 

[Guk22]

I have checked for codes, nothing stored. I drove it last night after it sat for more than a week. Started up, went right into gear and cruised it around for an hour or so. About as perfect as a 13 y/o truck with 185K miles could be!

When the reman trans was installed, they installed a brand new solenoid block. I don't suspect that is the problem as there are no codes. Like I said, the only thing I can find for "no movement" is "5R55W may exhibit a no movement or slipping condition after start-up. This condition can be caused from a sticking line pressure relief valve in the pump." This info is from "Superior Transmission P/N: K060".

Trans has fresh fluid and filter, it is topped off correctly. When it doesn't go into gear, there is no rhyme or reason. Revving the engine, letting it run to come up to temp, turning it off and back on all have no effect. Hoping someone can offer a suggestion!

 

[imp]

I have checked for codes, nothing stored. I drove it last night after it sat for more than a week. Started up, went right into gear and cruised it around for an hour or so. About as perfect as a 13 y/o truck with 185K miles could be!

When the reman trans was installed, they installed a brand new solenoid block. I don't suspect that is the problem as there are no codes. Like I said, the only thing I can find for "no movement" is "5R55W may exhibit a no movement or slipping condition after start-up. This condition can be caused from a sticking line pressure relief valve in the pump." This info is from "Superior Transmission P/N: K060".

Trans has fresh fluid and filter, it is topped off correctly. When it doesn't go into gear, there is no rhyme or reason. Revving the engine, letting it run to come up to temp, turning it off and back on all have no effect. Hoping someone can offer a suggestion!

Next I would suggest connecting a pressure gauge to the test port, perhaps plumbed up such that it can be kept in place (strong, in other words, capable of several hundred psi), and see if pressure loss is present when the fault occurs. This would be easier than yanking out the trans. to see if the pump is faulty. imp

 

[Guk22]

While searching for info on the test ports and pressure related info I found a lot of info from BrooklynBay and Glacier991. If the pump is faulty, wouldn't it be faulty all the time? As I've mentioned, most times the truck runs and drives as well as any. Why would the trans move sometimes and not others?

 

[imp]

While searching for info on the test ports and pressure related info I found a lot of info from BrooklynBay and Glacier991. If the pump is faulty, wouldn't it be faulty all the time? As I've mentioned, most times the truck runs and drives as well as any. Why would the trans move sometimes and not others?

The pump itself either works, or doesn't, but the flow control valve might just be sticking as you mentioned----sticking open, causing inadequate operating pressure. But, hydraulic problems are less likely intermittent than electrical, where vibration can cause a poor connection to make and break, over and over. Just a thought, but a faulty Transmission Range Switch, intermittent contacts, could cause a "no drive" condition. Next time it occurs, try ratcheting the gear shift lever from Park all the way down to 1, back and forth a few times, if the TRS is intermittent, it might just make contact. If that does happen, I would replace it. Cheap enough gamble. No luck there, try wiggling the wiring harness under the vehicle, especially where it may have some slack. imp

 

[Guk22]

I have tried slapping it thru the gears when it won't move with no changes. I do understand what you are saying about it more likely being an intermittent electrical connection, makes sense. Wouldn't it would throw a code if there were something wrong electrically? I am going to check all the connections and condition of the wiring. More to follow...

I appreciate your time and help! Thank you.

 

[imp]

I have tried slapping it thru the gears when it won't move with no changes. I do understand what you are saying about it more likely being an intermittent electrical connection, makes sense. Wouldn't it would throw a code if there were something wrong electrically? I am going to check all the connections and condition of the wiring. More to follow...

I appreciate your time and help! Thank you.

• "Wouldn't it would throw a code if there were something wrong electrically?"

• Yes and no. I'm no computer expert, but did study Digital Computers as a required course way back when computers were in their infancy. So, I try to second-guess just where the Engineers' minds are when deciding which functions are important enough to monitor them for possible error reporting. They have obviously placed emphasis on emissions-related issues; for example, the EGR Valve can significantly affect emissions levels, so they saw fit to place a sensor on it to monitor it's position. Thus, if it becomes stuck or inoperative, when the computer commands it to open or close, and it does not move properly, the computer "knows" about it, and issues an alert.

• Which brings up anpother point. Computer operates via a system of "inputs", interprets them based upon a program which it scans continuously, then issues commands to various "outputs", such as injectors, ignition coil, EGR, etc. It is much easier to include programming monitoring validity of inputs, rather than whether the outputs are occurring as planned. imp

 

[Guk22]

Very well put!

I'll let you know what I find when I climb under to poke around a bit.

 

[john cris]

did you get it figured out?

 

[Guk22]

Not figured out yet... I haven't had time to get under the truck yet to look around. Anything to add or have you experienced this issue?