Hey guys, I'm troubleshooting an issue on my 2002 F250 with a V10 and the 4R100 transmission. I thought I had this locked down and was going to fix it this weekend. Weather is preventing that, so I was doing some more road testing and now I think I am off on my original diagnosis. If anyone has some opinion on what I am seeing, I'd appreciate it.

Truck:
2002 F250, V10, 4R100, 2WD
280k miles
Original transmission and converter
Maintained religiously
I got stuck in the sand a few weeks before all this started and it was an ordeal to get out. I think I might have finally pushed something past it's limit.

Symptoms:
After warmed up to operating temp
-Torque Converter shudder/rumble strips around 35-45mph that clears up once converter locks all the way up
-Occasional high revs when taking from a stop light before moving
-When the high rev condition happens, it does not slam into gear. It's firm, but it's not the head jerking dumping the clutch or high-stall converter shift
-Operates perfectly on the highway
-Driving on the highway and then a quick stop in town is fine. It's when I drive all around town with lots of stop and go that seems to make this worse,
-I can't pull codes because my ODB port is not working. (Probably a ground issue. Fixed A LOT of those on this truck. Should be next on my list.)
-Although I cannot pull codes. The OD light IS NOT blinking like I think it would if a code was thrown.
-NOTE: Those symptoms do not happen every time I take the truck out. They happen a lot, but not every single time regardless of trip length.

Initial Diagnosis:
I though this was a classic torque converter starting to go out. Same symptoms from other vehicles I have worked on. My plan was to replace the TC and move on.

New Info:
Since I couldn't work on this today, I decided to just use it to run errands and see it I could reliably reproduce the symptoms. For some reason, I decided to put a tube of LubeGuard Shudder Fixx in there to see it that helped the shudder. I never use any of that stuff. So I don't really know what came over me, but I was reading a bunch of old threads last night and some members whose opinions I trust suggested that particular product. I figured why not. Well, that made it worse.

New symptoms:
-All the same shudder as before, but it lasts longer and starts earlier.
-High rev at stop lights almost every time now, but the shift is still smooth once it goes. If it does grab and take off like normal, then a few feet later it slips a bit then reengages,
-Manually shifting into 2nd makes the shake immediate and worse
-Manually shifting to first acts the same as if I put it in neutral.
-I was able to get to a place where I could test reverse while this was happening. Reverse is fine. No slipping. Immediate take off, etc.
-So it's a bit obvious to me that I screwed up using that shudder fixx as it seems that the friction modifier in there has made things too slick and whatever traction was left on the components is having a harder time engaging. If I try to be positive, I can say that maybe it has pointed to a more serious problem than the TC and might save me some time there.

New diagnosis:
-Slipping in forward, but not in reverse can't be a TC. It would do that in both
-Now I am thinking the forward clutch is shot. However, when this started a few months ago after that stuck in sand episode, I changed the fluid and there was not any metal. Fluid was a bit dark, but still red. Didn't smell burnt. In fact, I didn't think it was any different from other trans fluid changes on this one.

Thoughts? I'm thinking a rebuild or a new transmission.

 

I can't come up with any way the first gear problem could be the torque converter. If the converter were bad, it would be bad all the time. It wouldn't be a problem in first, then work fine in second. The shudder when it locks IS the converter, though.

I think you have a bad forward clutch.

 

Thanks for the input, I was hoping you would see this. That's the same conclusion I got to with the second set of observations. Back to the drawing board for a new plan, I guess.

 

One other question I forgot to ask: Is it worth looking to see if the feedbolts have backed out, or is this just a textbook bad forward clutch and I should plan accordingly? I put it through the wringer getting unstuck last time. Oddly enough, though, it mostly reversing to get out that time.

 

That is possible.

 

For my own sanity, I just "sampled" the fluid with a white towel instead of my usual blue ones. If I only dab the end of the dipstick from the bulb to the actual fluid, It is still pink and smells like Mercon V and not burnt. Wiping the towel further up the dipstick gets some darker stuff, but I suspect that is accumulated grime since no fluid can really get that far up the dipstick tube. Fluid was changed about 1700 miles ago. That should be enough time to see some indication of clutch deterioration, right?

So,since this started shortly after getting stuck, could this actually be the feed bolts? I don't know what causes those to come loose or how common that is. There was a lot of aggressive forward/reverse rocking to get out of that pit. Would that stress combined with the age of this transmission cause these to loosen? I'm still concerned that it's a bad forward clutch since the additive seemed to make things worse. However, I drove it today and it seemed a bit better. Just letting off the brakes at an uphill stoplight pulled the truck forward with just engine idle speed. It hasn't done that in a while when warmed up. Of course, that could be wishful thinking bias.

Checking those bolts makes sense, I guess, and I might get lucky. I was going to flush the fluid again anyway to get rid of that additive assuming I can find enough around town to do it.