Hello, as some may know, I bought a 97 with 71K miles on it and have been going through checking and replacing everything I can find wrong with it. The front end has been rebuilt, KDP tabbed, a few small leaks fixed, etc.
Anyway, we just got back from camping today with our camper. It weighs about 7100 lbs loaded out. The truck did great going and the whole time we were there. However, on the way home, I noticed it was not shifting the same as it had been. It was slow about coming out of overdrive on hills and seemed to really lug the motor down unless I pushed the button to take OD off. The truck will only run about 65 WOT with OD off, so I don't run with it off much. Even at 55, the RPMs are 2400. A few times going up the hills, if the speed got down to around 50-55, I would get a shutter. If I pushed down on the throttle, the TC would unlock and then lock back shortly. I checked the fluid on the fuel stop, and it was slightly brownish where it was red when I left the house going. The trip was about 700 miles round trip.

When I got home, I dropped the pan. The fluid was pretty bad and the pan magnet had a good bit of material on it. I cleaned it all up, put fluid in it and drove it. Unloaded, it seems to shift fine. How can I tell how much damage has been done?
Thanks,
Chris

 

No one knows until it is apart on a bench. But, I 'd guess it is on its last leg. They don't take kindly to slippage.

 

until u mentioned the fluid id say its paranoia....anything below 1500rpm locked up ur gonna get shudder especially loaded....going up a steep hill with 7000 lbs locked is gonna force the the TC to unlock...i think thats pretty normal....mine never wants to unlock...dont ask why...my tranny does NOT downshift...u have to get ur foot off the gas for a split second to get it unlocked or downshift

BUT if u were going up hills for extended periods of time with a load UNLOCKED the u better keep a close eye on the fluid each and everytime....alot of guys on here that tow really heavy and often change their fluids once every 2 months! or less!

as for a stock 12 valve...running at 2400rpm it will fall on its face....stockers get no power beyond 2100rpm....of course the 4k GSK's will allow u to run at 3000 if u want with full fuel delivery...nothign will slow u down then

 

Not paranoid, sounds like the fluid did get trashed... Did it have a burned smell?

At least you changed it.. did the filter, too, right?

Keep an eye on the new fluid, you might have to change it again if the old fluid was that bad.

That shudder sounds like TC clutch slippage. Does it do it now? maybe hook up the camper for a quick spin?

 

I plan on changing it again in a week. I pulled the filter and wiped off the magnet on a plastic bag. I will be taking it to a transmission shop where a friend of mine works this week. I was going to let him pull the pan, but there was just no way he could get to it until next week. He is the only shop in this area and stays backed up. On the good side, it did not have many "chunks" in it. I have seen a few pans with small pieces of material in the pan and go for miles and miles. This pretty much just had an odor and fine material on the magnet. When I wiped it off, it just looked like oil sludge.
Chris

 

Had similar experience except my trailer is closer to 11m lbs. When tranny fluid was changed there was a fair amount of ground clutch material in the pan. Once fluid was changed I couldn't tell that anything was wrong, but was told that I would likely be left on the side of the road if I towed my trailer on a long trip again. Since we're planning a long trip soon I had it rebuilt HD. Of course since I had more power capability in the trans I made some changes that really improved the truck's performance. Don't mean to spread doom and gloom but that was my story and I'm sticken to it.

 

You can probably buy some time if you put a good shift kit in it. This will up the line pressure and you can also increase the volume and pressure going to the TC which will help to eliminate the "shudder". I have done a bunch of these so PM me if you want any recommendations.

 

At that mileage with clutch material in the pan its only a matter of time. Unloaded, you might get a lot of mileage out of it, but I wouldn't trust it towing heavy for much longer.

These autos don't have much clutch or band material to give up at all, so any decent amount in the pan is a really bad sign.

 

I dropped my pan, and changed the tranny fluid about about 20k miles ago. The TC was slipping HORRIBLY in lockup, and shifts were kind of slow. It also had the sludge on the magnet, and a few fine shavings. Changed the fluid, and filter, and slapped in a $50 Transgo shift kit i got off ebay, and man what a difference. Transmission shifts great now, and the TC holds a LOT better. I have been rough on my tranny that 20k miles. Hauled all summer with it last summer, and lock the TC from a dead stop mashing it when i get beside those powerstrokes to show them who there daddy is . I havent been easy at all on my tranny, and even though you would have thought it was ready for a rebuild when i pulled it apart before, its still doing good. The TC does slip some WOT and it will slip a lot with a trailer if you dont watch it. So with a trailer i just make sure, and watch how i drive with the TC locked, and its fine. The less throttle you give it, the less pressure the TC has on it, so more throttle is generally better. My TC has always shuddered. Just drive the thing till it does give out, and then have it upgraded. People can talk all the trash they want about a 47rh/re, but i will hold up for it. Mine has been good to me, and i think they are as good as any other tranny out there as far as longevity in a stock truck.

Eric