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Discussion Starter #1
Hello,

Just got the torque converter bolt holes taken care of and have driven it for a week or so.

Driving to down the highway tonight going to work and all of a sudden I hear a loud BANG, feel a jerk and loose power. I pulled onto a side road. Had wife bring a dolly. Could drive it onto the dolly and then when got it home could back it off. Started engine to move it in driveway and it won't move forward or reverse. When in gear I can hear a faint almost grinding noise.

Almost forgot to include the info. 1989 Dakota 4x4, 3.9L engine, 4 sp automatic transmission.

Any ideas or suggestions on what to do or how to start troubleshooting?

Thanks for reading!
Danny
 

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Other than the faint grinding noise, it feels like it is in Neutral? I suspect that something mechanical has let loose, but something is still turning inside for the noise to happen.
If the vehicle can be safely chocked with the parking brake on, see if you can locate the approximate source of the grinding. That will probably be the point of the drivetrain disconnect.
ATF line pressures can be measured with a gauge to see what elements are receiving pressure. Does the transfer case range make any difference? Maybe drop the transmission pan for a look?
 

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Discussion Starter #3
Had a little time to look at it this afternoon. The grinding noise is actually a whining noise. I got the impression that it is the pump whining. It was strange. I pulled the trans dip stick, wiped it off and put it in and pulled it again, there was fluid up on the stick (near full mark) but, looked like there wasn't fluid down lower. While it was still cool could move forward and reverse. Let it idle 15 minutes or so and wouldn't move either direction. I did add some fluid and still wouldn't move. After it warmed up I didn't hear the whining sound.

Hopefully, it will be a little warmer tomorrow and I'll try adjusting the kickdown band to see if that may help.

Any other ideas?

Thanks for reading!
Danny
 

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Discussion Starter #5
Just finished pulling the pan off. Everything looked fine. Very little fuzz on magnet. Then sun hit fluid in pan. Saw quite a bit of, I guess you'd say, metal shavings reflecting in the sunlight.

Am I correct that this probably means that I either have to rebuild this transmission or find a different one?

Thanks,
Danny
 

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A metallic sheen is from wear. It may or may not be fatal. How old is the fluid?
A pressure test would determine if the pump can meet pressure demands. A large internal leak would also keep the pressure from reaching spec.
It still may be worth some more diagnosis before possibly having to pull it out.
 

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Discussion Starter #7
Update,

It appears the transmission isn't dead. I replaced the transmission filter and fluid. Now I have 1st, 2nd and 3rd gears but, no OD. The little I've driven it I didn't notice any slipping, just no OD.

As brown as the fluid was and with all the crud that was in the bottom of my drain pan I'm assuming the main cause was a clogged filter.

Am I correct in assuming that I still need to pressure test to see about the no OD problem?

Thanks,
Danny
 

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I don't have an '89 truck service manual for O/D diagnosis, but is there an O/D off switch on the shift lever or on the dash? Is there an O/D off light that comes on at start up? Was O/D working before the bang?
The filter plugging may have been gradual and not sudden, things just came to a head all at once.
I'm glad to hear that you have some transmission operation restored. It may be OK.
This may be too early for the fully-electronic O/D in the 42RE and is a hydraulic O/D, like in the 42RH.
A diagnostic procedure in a service manual would help here. It just stays in 3rd gear?
 

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Discussion Starter #9
As far as I know the OD was working before the bang. At this point it shifts into reverse, 1st, 2nd, and 3rd. While driving down the road I push the O/D off switch and nothing happens, other than the indicator light comes on. I've tried 4 wheel drive and it works also.

Unless I'm missing something the factory service manual is pretty much worthless in diagnosing this. It has about a page and a half General Info then a chart that contains conditions and possible causes:

Condition - No overdrive shift. Possible Causes - (a) Blown Fuse
(1) Faulty overdrive solenoid.
(2) Faulty wiring or connectors.
(3) Faulty Overdrive off switch.
(4) Faulty SMEC.
(5) Failed Overdrive Clutch.
-Wrong overdrive piston bearing spacer selected.
-Low overdrive pressure.
(6) Lower valve body malfunction.
Then tells how to remove the OD Unit and on into how to disassemble and repair. It doesn't show or say anything about how to troubleshoot any of these items.

From the list above I'm wondering if it is either 1) faulty overdrive solenoid, or 2) failed OD clutch, or 3) lower valve body malfunction. Any suggestions on how to troubleshoot any of the above items?

For now since everything except OD seems to be working properly with no slipping of the transmission would it hurt anything to just drive it like this?
 
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