A couple months ago my truck would not shift into 3rd or 4th (but I still had reverse) so I parked it. Figured it was way over due for a flush so I got some fluid and filter but didn't get a chance to do the flush. A few weeks later I had to run to the store and took the truck, this time the transmission shifted just fine like nothing was wrong.

Today I jumped in and ran to the store, once again it would not shift into 3rd. When I came out of the store I tried to back out of my parking spot but it would not move in reverse. I took my truck to my buddys shop and did the flush and pulled the codes. The codes are P0733 and P0782. The fluid was dark and smelled burnt but the shavings on the magnet looked about normal.

If I rev the engine it will engage in reverse, I tried it while rolling backward down a hill. While driving, in 2nd if I let the RPMs get to around 3000 it will shift into 3rd but if I let off the accelerator even a little bit it will shift back down into 2nd.

Could it not be getting enough pressure to make the shift?

Yes I understand there are many of you just waiting to post the obligitory "Time for a new tranny" message, but honestly I am more interested in what is going on with the transmission. I am trying to learn more about automatic transmissions.

 

It could be a bad seal in the direct clutch. It could be loose feed bolts behind the valve body.

 

Thanks for the reply Mark.
I never felt it slipping during shifts so I am wondering if the low line pressure caused the burned fluid. I realize the transmission is pretty much toast now and needs a rebuild so I figure I don't have much to lose if I dig for the feed bolts and see if they are loose. I don't have a ATSG book yet so does anyone have a diagram of where the feed bolts are?

 

I found a picture. Google to the rescue.

 

Of course, now you HAVE to come back and let us know how this turns out!

Here's hoping for an inexpensive fix for you.

If you didn't find this photo,

here's something else at which to look.

Pop

 

I agree with Mark, but I also think that when the feed bolts are loose that it lets the center support move around. Which it should NOT move at all and when it does move from loose feed bolts it does BAD things to the bushings and center support bearing. So if tightening the feed bolts cure your problem it is only a short term fix. So yes it is time for a rebuild.

Now if you are going to pull the valve body to tighten the feed bolt I would also install http://www.sonnax.com/system/announcement/36424-24K.pdf to help you buy time before rebuild. But not trying to be negative here but it's time to have it rebuilt.

 

I realize it needs rebuilt and I am not necessarily trying to prolong the death, but like most of us on this forum I am not the kind of person who just takes my truck to a shop and says "do whatever it takes to fix it". I want to understand why it failed and I may take a chance at throwing a few thousand bucks down the drain by attempting the rebuild myself....but I have a lot of learning to do first. So thanks for the feedback.

So do the feed bolts hold the center support in place? This seems to be a common problem, what do you do to keep them from backing out?

 

BJ I too just want to know the what and why of why things break or don't break on this 4r100. I am like a 3 yr old child "Why??Why??" So I will try to answer your question the best I can. I still have alot to learn about these 4r100 but I am learning as I go.

Now yes the feed bolts hold the c.s. in place but so does the intermediate clutch piston return spring. Which holds it from the front of the center support and the other side of the return spring pushs up again the IM/OD cylinder assy. And the IM/OD cylinder assy is held in place by a snap ring.

Also another modd to stop the feed bolts from loosening up is to use c.s. feed bolt shim. http://www.sonnax.com/system/announcement/36743-01.pdf And actually there are a few more mods that can be done to the center support.

 

Well today I had a chance to tear into my transmission. All was going well until I got to the solenoid pack. The 4" exhaust made it hard to get to the connector on top but it came apart surprisingly easy with a flat head screwdriver. I took the bolts out of the solenoid pack and was trying to wiggle it loose but it wouldn't budge. I tried to push down on the connector from the top but it still wouldn't move. Finally I used a little too much force and broke the connector off of the solenoid pack. So I pulled the plate off and checked the center support feed bolts, they were all tight. There is a ton of clutch residue all over everything. So I slapped it back together and pushed it outside. Now to decide if I want to have a transmission built or start gathering parts to rebuild this one. Here are some pics







Here is the broken connector

 

BJ I am sorry things are not going your way on this trans. And from what you first wrote and from what Mark said and the fact the feed bolts were tight I would think you have a bad seal in the direct clutch or a bad piston seal. It also still has me wondering if the accumulator springs & valves are hanging up or stuck from all the material in the fuild. It might even be a line pressure modulator valve. http://www.sonnax.com/system/announcement/36948-03K.pdf

So now it comes down to how deep are your pockets as far as what to do next?? Because it doesn't sound like there is going to be any quick fix.

 

Sounds like you should just send it to ED. Just joking, but he did do his own thats more then I could of done. BTS sounds good around now. Good luck and Happy holidays to all.

Chet