I have searched many other threads for some guidance but would rather not hi jack someone elses post. so he is my plea.

03 Exc 7.3 135,000 mile; the transmission has completely given up. I might be in denial but I can't seem to diagnos the cause. After sitting for a while it will start out but almost no power. Once the truck stops it won't move any more unless I let it sit an hour. Here's what I've done.

-Checked fluid level: normal in range.
-Wiggle tested all electrical connectors- no codes popped.
-Pressure tested at idle: N 50-65psi, R 90psi, 2nd 60psi, 1st 35psi (failed)
-Lowered pan: found lots of metal sludge on magnet and a few bits of non metalic.

recently changed filter and fluid in the pan. about two years ago swapped silenoid pack but diddn't need to because dirty fire wall plug was the problem then(thanks Mark). i still have the oem pack on the shelf. I rarely tow and nothing over 4k

Is there any thing else I can check while the gearbox is still in the truck? would a catostophic failure be more visible in the pan. I have not read resistance on the silenoids because of the lack of codes. Am i missing something simple like a stuck valve. If so could I just rebuild. I know most guys would be excited at the oportunity to upgrade the gear box but money's tight and I also don't have a lot time to wait for custom jobs. Any advice is greatly appreciated before I try to rebuild.

 

Does it act the same in all ranges? R,D,1,2,3? Did this happen all at once or has it gradually gotten worse? Can you feel the truck "bump" into gear at all"

Does the oil smell/look burnt? or looks like it has black pepper in it?

 

The problem happend rather sudden. I had not noticed any problems leading up to the failure. Maybe bad fuel economy but that might be many things, like ideling to long on cold mornings. The fluid is not burnt and neither was the fluid I changed a month ago the only contaminats in the fluid was the metalic sludge on the magnet, alot more this time than a month ago. Wifey was actually driving when it happened. she says she had driven around fine that morning then just lost power after what she says felt like a flat tire.

 

With it having it happen all of a sudden like that, you could have possibly snapped the input shaft, or one of the shift solenoids has failed. I'll have to do some digging one what members are held and which are driven for each gears and the electronics to come up with anything else right now.


When you put it in gear does it make it any kind or noise or vibration? You might try chocking the wheels, setting the park brake, put it in gear and kneel down beside it to see if you can hear anything unusual

 

Thanks, I have been listening and there is a slight rubing and rattel noise nothing very loud. I guess the big question is; is it ok to replace the failed component i.e. shaft, valve and not rebuild the whole thing?

 

There is nothing electronic that could have done this. Something mechanical broke.

You can pull the trans out, fix/replace the broken part, and put it back together.

 

Thanks Mark. I will pull it tonight and inspect for obvious broken parts. What would you suggest for rulling out a shuttle valve or ball valve being the culprit?

 

They are easy to rule out. They can't cause this. Something mechanical broke inside the transmission. A shaft, a shell, a gear, etc.

 

I just got it on the deck. Took me a while because I cheated and didn't drop the exhaust, so I had to reach from the right side to get the last to bolt. Fortunately I'm a small guy so I fit after some squirming. I'll have to make a fixture to support it upright. That's enough for tonight. I'll post results tomorrow after work.

 

I've got the pump off everything seems to be intact. I'll be pulling the intermediate assembly next and continue to check what could have broken. My ATSG is really good but doesn't say what the parts should look like or how to check for serviceability. One question I have is: should the pump shaft be able to spin by hand? Because mine won't move. Also after an hour of scratching my head I found the lugs where the pullers go for the pump. More to come later.

 

in my opinion you have it out and it has 135,000 mi on it i'd rebuild it before i put it back in just my .02

 

Subscribing. Hope you ID the problem and are able to resolve it with minimal parts cost. If the fluid isn't burnt and there's not a lot of friction disk material in the bottom of the pan, then this tranny might still have a lot of life in it.

 

I've gotten down to the reverse gear assembly and nothing seams to be abnormal. I did notice the fluid that came out of main valve body was a little darker and smelled different. I have not yet disassembled the direct drive clutch but the doesn't seem to be any sign of damage there either. The output shaft also seams to be intact. The only two part I have not looked inside of are the torque converter an the pump. I hate to reassemble without knowing the cause of the malfunction. Could it be something unnoticeable like a tolerance? By the way does anybody know where to get feed bolts. The book says they are one time use.

 

The pump is a likely suspect.

 

Sounds like you better take a look inside the pump. Hope you figure it out soon!