Transmission fail Chevrolet Van G20

[nonickatall]

Hello,

I accepted a job to repair the transmission in a friend's Chevy van.

It's a 4L60 E.

My friend was driving, and suddenly it lost all traction. Neither forward nor reverse. According to him, it didn't make any noise.

Since I've repaired several Chrysler automatic transmissions before, he asked me if i cam help and I accepted the job and began the overhaul. I disassembled the transmission using a service manual.

I've now completely disassembled the transmission, but I can't find any damage.

There were no debris or chips in it.

I've read about problems with the oil pump and the gears that mesh with the torque converter, but they're fine. I've also read about defective torque converters, but I haven't found any problems.

Is there a way to properly check the torque converter, or what could indicate failure?

Does anyone know what else the problem could be and what I should check?

@nicktransmission. If you're reading this, can you help me? I know you're an expert on these transmissions. I would appreciate your advice.

Best regards from Germany
Ralf

 

[nonickatall]

I did some more research and looked at the possible causes of this problem.

There is this sprag, which seems to be fine in my case.

The sunshell which also seems to be a cause is in a good condition.

Furthermore, it is repeatedly pointed out that the oil pump could be defective. From my perspective, my oil pump looks almost new, no wear marks, no play and the noses of the drive pin are still there.

However, I took a closer look at the torque converter and noticed the following. When I put the disassembled oil pump housing, which contains the corresponding drive pin that engages with the converter and the disassembled input drum, whose shaft also engages with the converter, into the converter and turn the whole thing, I hear a grinding noise when I turn the input drum. I have a second converter from a 4L 65e here, which should be identical.

There is no oil in it, but nothing is grinding.

Is it likely that the problem is coming from the torque converter and are there further inspections that I can do to verify this?

 

[89Suburban]

@NickTransmissions

 

[NickTransmissions]

I did some more research and looked at the possible causes of this problem.

There is this sprag, which seems to be fine in my case.

The sunshell which also seems to be a cause is in a good condition.

Furthermore, it is repeatedly pointed out that the oil pump could be defective. From my perspective, my oil pump looks almost new, no wear marks, no play and the noses of the drive pin are still there.

However, I took a closer look at the torque converter and noticed the following. When I put the disassembled oil pump housing, which contains the corresponding drive pin that engages with the converter and the disassembled input drum, whose shaft also engages with the converter, into the converter and turn the whole thing, I hear a grinding noise when I turn the input drum. I have a second converter from a 4L 65e here, which should be identical.

There is no oil in it, but nothing is grinding.

Is it likely that the problem is coming from the torque converter and are there further inspections that I can do to verify this?

Grinding noises in the TC should be sufficient enough evidence point to it as the cause....The following things will cause a no-movement condition in these units:

1. Pump failure
2. Input shaft splines stripped at the converter
3. Failed converter (stator one-way clutch, specifically)
4. Failed EPC (restricts all line pressure)
5. Failure to connect the manual valve to the rooster comb via the linkage arm
6. Failed fwd clutch + failed coast clutch + failed low-reverse clutch + failed low roller clutch
7. Significant deficiency of fluid in the unit; acute, massive fluid loss (cooler line separating from the transmission while driving)
8. Destruction of the gear train and/or output shaft due to restrictions or RPM/use and abuse