1997 4WD F350 7.3

I was trying to dump a trailer with a sticky load up a hill, punched it hard in reverse with a big load & heard a bit of a rattle noise after let off the pedal that lasted for about 5 seconds.

drove normal after but an hour later while hauling a big load up hills, trans temps went up fast to 240 and lost power at the transmission, dumping fluid from cover. shut it down, towed it home, drove it off the truck, it went into gear and moved but was slipping and behaving like low on fluid which it was

It was driving fine for the 15 miles between the noise and the over heat.

dropped the trans, appears the front seal is leaking but hard to tell, fluid not burnt and fairly red, last change was at around 40k with temps 190 average & 220 occasional. Have not separated transfer case or anything besides pulling off the TC. Pan is still on it too.

truck has been modded ~100+hp over stock in mods with TW tuner, stage 1.5 and few other mods, nothing crazy and have driven the truck gently for most of the 40k miles since last trans fluid change. It has shifted great with no transmission issues. before and even up to power loss. previous owner claimed to have replaced/rebuilt transmission about 70k ago.

Plan to replace the seal and put it back on the truck. Any checks I should do while it is off? inspect the internals? I haven't taken the pan off, I put a plug in it last time I changed fluid and drained it that way, not a lot of fluid came out. TC looks good with no loose parts or other metal pieces in the case.

Have always planned to replace the transmission with a BTS built one once it gave up but I want to get what I can out of this one and I didn't expect a failure so soon.

Any advice on diagnostics before I put it back together with new seal? I considered refilling fluid and testing it first but I am pretty sure seal is bad and fluid ain't cheap.

 

Check the polished end of the torque converter where the seal rides. If it has ANY damage the new seal will leak, too. Also check the bushing that the converter rides on. If it's worn, replace it. They are really inexpensive.

There is a better seal available. It's made from a material called Viton.

 

THANKS MARK! MUCH APPRECIATED

 

can you provide the part number for the bushing? I want to make sure i order the correct one. Opened up the pan and pulled off the seal, everything looks as it should. Fingers crossed a new seal and reinstall the transmission and everything is good to go for a while.

I am installing a larger transmission cooler.

thanks, for help! DH

 

No, I can't. I don't know the part number.

 

Hey get a Zf! bro

 

Next time use 2 low when backing up heavy loads. It's heaps easier on the transmission and everything else in the truck.

 

that is great advice... I didn't think about it when I was doing it and I was just pissed the dump trailer wouldn't tilt high enough and that the load was not breaking free and dumping with the reverse incline.

Looking back it was a lot of load on the transmission. I was mashing the accelerator in reverse up a grade to try to get max momentum in 10 feet then hitting the brake to break the load loose. 2 low would have been a lot better. Next time!

I have been slow to get going on this project but this weekend I should have the new seal and bushing and put the transmission back in the truck with a new cooler. Knock on wood it works... even after the reverse indecent the truck drove fine for 15 or so miles until we hit a really steep grade with a fresh heavy load in the trailer. My best guess is the fluid was slowly leaking after damaging the seal earlier and low fluid was the issue. Before all this the transmission was working great and never a slip or bad shift.

Is there any way to know if the TC is good while we have it out? It looks good and nothing appears to be loose inside but I have no clue.

 

Carefully check the polished snout where the seal rides. If there is any damage the new seal will leak. Other than that the only way to check the converter is to cut it open and inspect it. Then have it rewelded and rebalanced.

 

Unfortunately you're in a catch 22 situation.

There is no real way to know if you've done any real damage to the transmission without taking it apart.

You could put a new seal in it, get it back in the truck and be totally fine. You could also put it back in the truck and have it slipping and puking fluid again.

If I were you, I'd bring it to a reputable transmission shop and spend the few hundred dollars or whatever they charge to inspect it. That way you're not guessing.

Sure it would suck spending that to have nothing wrong with it, but the piece of mind is worth it to me.

 

These trucks are famous for belching transmission fluid when straining in reverse. There are lots of reports of the seals letting out fluid and then resealing themselves without other intervention except adding more fluid to replace what's on the ground.

I had that happen to me after a long haul up the mountain, then a lot of reverse usage backing into a slot. The thing poured out many quarts of fluid, but has given no further problems in the past 10 years.

 

that is really interesting. I didn't know that. I hope that is the case for my truck. I don't think there was much leaking during the backing up, it was on my brothers driveway and I would have seen the fluid. It could have been leaking for the next 10-15 miles and when it hit the grade a couple hours later is when it really dumped hard. The seal is gonna be replaced as well as the pump bushing even though the TC surface looks great.

It was gonna be $400 for a shop to break it down and put it back together. Since; it is a not a daily driver, I'm cheap and if there is something wrong I will probably do a heavy build not at a local shop, I am crossing my fingers and buttoning it up with a better cooler and lines and will see what happens.

 

follow up:

truck is back together and all systems running great. With new cooler the trans temps never got over 140 but the ambient temps so far have bee 20-70 degrees and no towing but some mountain driving. Before 190 was the norm.

Transmission seem to be shifting great and no leaks or issues. I have run about 600 miles in the last 5 days since it was put together in mountains/ hwy and city, 4WD and 2WD.

Lessons learned:

- how to correctly install a TC, we did it wrong the first time and had to jack the transmission 2x

- I am more familiar and comfortable with the inside of the transmission now, took apart the OD clutches and took out the OD planetary to look at it and get it back together after we replaced the pump bushing.

-how to pull a transmission and TC, we got to do it 2x . it is real heavy with the transfer case attached.

Questions:

1. The TC that was in my truck was labeled as a F550... written in sharpy. What is the stock F550 TC? is is different than a 350?

2. is the OD planetary for the powerstroke E4OD suppose to be a 4 pinion steel or should it be 6?

that's it! Hope the transmission holds up for many more years, fingers crossed. Once it gives up I think I will tear it apart and look what went wrong and rebuild or go with a BTS package.

Thanks for help!

 

There is no difference in converters between an F-250, F-350, F-450, and F-550.