Bad converter or something else? No DTC's

[LBZLT3]

Recently went on a long 300-mile drive and when I finally came to a stop, I heard a whining noise, almost like a PTO. As soon as I shifted into N or P it went away and I felt the truck relax. So, I figured the TC was going or maybe the VB or Solenoids were clogged etc. I dropped the pan, other than the fluid being slightly dirty, there wasn't any debris in it. I would have figured I would see something in there. It was clean as a whistle. I even strained the fluid with a super fine mesh. So, I bought all new OE solenoids, manifold and a transgo while I was in there. Cracked the VB open to make sure to clean the filter in there too. All really clean. It's reassembled now and it does the same exact thing still. Looking at the live data, the TCC command pressure is 0 at idle. I wasn't able to find a table to go off of for these values to confirm if it was correct. My thoughts are, either it's a wiring issue or TC. I kind of think I caught it early since there wasn't anything in the pan as far as debris. Any thoughts? I should have checked the internal harness while it was apart, but I was kind of rushing to get this back together.

 

[2004LB7]

Have you logged converter RPM/slip?

 

[LBZLT3]

Have you logged converter RPM/slip?

Yea, the zero slip is park. The other is in drive.

 

[PureHybrid]

Logging slip at a standstill won't do any good as the clutch should not be trying to apply. The pictures you posted look correct though, in drive or reverse the turbine speed should drop to zero until you start to move

Going by your user name, it's a 6 speed truck? Do you use elevated idle a lot during cold months?

 

[LBZLT3]

Logging slip at a standstill won't do any good as the clutch should not be trying to apply. The pictures you posted look correct though, in drive or reverse the turbine speed should drop to zero until you start to move

Going by your user name, it's a 6 speed truck? Do you use elevated idle a lot during cold months?

I use high idle when its cold, yea. Someone mentioned the sprag could be shot inside the TC. There is zero slip at all. Well, i mean theres some because it doesnt stall but you know what i mean.

 

[PureHybrid]

IIRC during high idle the TCM starts to trim the TCC solenoid on to create a little load on the engine to aid in warmup. Caused some premature converter failure. Related to your issue?? Maybe not.

If the converter is failing the debris will be sent to the cooler first, pan usually stays clean. Remove bottom cooler connection at the radiator and look for debris stuck in the cooler fins.

Honestly it's probably pump noise you're hearing

 

[LBZLT3]

IIRC during high idle the TCM starts to trim the TCC solenoid on to create a little load on the engine to aid in warmup. Caused some premature converter failure. Related to your issue?? Maybe not.

If the converter is failing the debris will be sent to the cooler first, pan usually stays clean. Remove bottom cooler connection at the radiator and look for debris stuck in the cooler fins.

Honestly it's probably pump noise you're hearing

Why would it only whine in gear and try to push through my brakes?

 

[2004LB7]

Why would it only whine in gear and try to push through my brakes?

Classic sign of a failed converter

 

[LBZLT3]

You think its worth just putting in a TC and running it or do a full rebuild? I really dont want to spend the money right now rebuilding it but this isnt really my area of expertise.

 

[JoshH]

What does engine RPM do when you accelerate from a stop? Does the converter allow the engine RPM to flash up to a higher RPM, or does it act like a manual transmission with a clutch? What your scan tool is showing is completely normal. You should see no slip in park/neutral as there is no load on the input shaft of the transmission (turbine speed is free to match engine RPM with no load meaning no slip). When you place the transmission in gear, the input shaft is locked to the output shaft which means the turbine will stop and will turn at a speed relative to the output shaft and the gear ratio that is engaged. At a standstill, this will result in 100% slip.

 

[PureHybrid]

Why would it only whine in gear and try to push through my brakes?

The way I read your post it didn't sound like it was pushing through the brakes.

Is the truck tuned? If not, you could definitely get away with only a converter. If it was mine, I'd be tearing the stator assembly apart while I had the transmission out to check the pump and the converter valve

 

[LBZLT3]

What does engine RPM do when you accelerate from a stop? Does the converter allow the engine RPM to flash up to a higher RPM, or does it act like a manual transmission with a clutch? What your scan tool is showing is completely normal. You should see no slip in park/neutral as there is no load on the input shaft of the transmission (turbine speed is free to match engine RPM with no load meaning no slip). When you place the transmission in gear, the input shaft is locked to the output shaft which means the turbine will stop and will turn at a speed relative to the output shaft and the gear ratio that is engaged. At a standstill, this will result in 100% slip.

No surge in rpm. No slip at all. Put the truck in gear, and it feels like 4w lo trying to push through the brakes. Put it in neutral or park and it goes away immediately. Rpms are noticeably lower as well in park or drive when stopped

 

[LBZLT3]

The way I read your post it didn't sound like it was pushing through the brakes.

Is the truck tuned? If not, you could definitely get away with only a converter. If it was mine, I'd be tearing the stator assembly apart while I had the transmission out to check the pump and the converter valve

No tune.

 

[JoshH]

My guess would be a bad stator sprag. If the clutch was locked enough to create a no slip condition like you are describing, it would also likely stall the engine. They aren't a common failure, but I have seen them fail.

 

[2004LB7]

Might be a good idea to get that truck on a transmission hot flush machine to make sure there is no debris in the cooler or other areas that will damage anything after a new converter, rebuild or whatever you decide to do

 

[LBZLT3]

Might be a good idea to get that truck on a transmission hot flush machine to make sure there is no debris in the cooler or other areas that will damage anything after a new converter, rebuild or whatever you decide to do

I would just replace them to be honest. They are the original lines and cooler.

 

[darkness]

I would just replace them to be honest. They are the original lines and cooler.

That would also include the radiator too. This came out of mine when I lost the stator.

 

[Bdsankey]

I would just replace them to be honest. They are the original lines and cooler.

It is incredibly wise to replace them or at minimum have them professinally hot flushed.

For example, I will instantly void the warranty on a transmission we build if a customer fails to replace the coolers or provide a receipt for professional hot flush before the transmission is installed.