Had shifting issues in my 92 f250, fixed the sensors. When I went to change fluid, no plug in aftermarket TC. Went to disconnect line to do a flush, there is absolutely no flow. I double and triple checked, there isnt a plug in the lines. I disconnected the front line from the transmission, turned the truck on, nothing came out. Fluid smells very burnt. Is the front pump somehow bad? Every post I find says a front pump failure is the seal blowing and puking out fluid, which isnt the case. There is just no flow. Trans is definitely running hot, gets to 200 driving around town, and that's with the radiator cooler and an aftermarket. Is there something I could have missed that would cause no flow? I ran it for about 15 seconds at a time, even tried revving it, but no flow.

 

It shows fluid on the dipstick?

 

If the trans engages and moves, the pump is working. If there is no flow out of the trans there has to be a blockage inside the trans or torque converter.

 

Also if this truck is new to you make sure the cooler lines are not bypassed. I have seen this many times. The lines rub on the cross member and people bypass them with a loop. This ultimately overheats the trans.

 

Wow. You unhooked the front line at the trans but nothing comes out,so next I would unscrew that adapter fitting and see if your blockage is right there.


Hmm. It almost makes me suspect if someone installed the fittings incorrectly? Are the the same size and is this possible,does anyone know right off? If they got mixed up and or if someone installed a rear one in the front and if the check ball is seized up,that would explain it........Well no,it wouldn't need to be seized up,the fluid would be pressing it closed I guess.



If these are different sizes and this isn't possible,then disregard but pull and inspect it anyway.There should be no drain back check ball in the front fitting and it shouldn't be plugged of course.Might want to start the truck again with it removed too if you don't see anything obvious.Just a sec or two though cus when she does free up (hopefully) you'll pump out a lot real quick.

 

Everything is stock up until the front where theres an aftermarket aux cooler (believe me, I'm now INTIMATELY familiar with how the diagrams are laid out).

I did disconnect the front line at the tranny, no fluid came out. It's my understanding only the rear fitting has a check valve? It's all hard line, so I know they didnt actually swap the lines themselves. Is it possible to accidentally swap the fittings between the lines, putting the check valve on the send line? I'll have to pop off both at the tranny tonight and take a look. The rear is the only one with a check valve, yes?

 

So Mark, are you saying that it could be blocked internally (before it even gets a chance to exit the trans via the front line) while still operating the pump and allowing shifting, or that if it were actually blocked the trans wouldn't shift?

 

Hope this doesn't sound too stoopid but are you checking for flow on BOTH lines?

When I did Mark's full flush method on a 2000 4R70w only one line had actual fluid flow out---I checked both and simply replaced the one without out fluid flow.

All this was done at the hose connection leading into the radiator cooler on an '00 E250's 4R70w.

 

Yes, that is correct. But if someone put the rear connector in the front location you'd have what you are seeing.

Yes.

Only the front line will have flow on a 4R100. That's the trans out. The rear line on a 4R100 is the return from the cooler. There is no flow out of the case here, and there is no suction on the rear line.

A 4R70W has a top and bottom line instead of front and rear. I can never remember which one is out and which one is in.

 

Well Mark, hopefully it's just swapped fittings. I actually haven't had time to check, Christmas has been pants on head crazy at my house. Assuming the fittings are installed correctly, would I have to assume it's an internal blockage somewhere? At this point I'm really hoping it isn't, because auto transmissions are pretty much the one thing I won't work on myself, and I'm sure a trans shop will charge me a pretty fair sum.

 

If the fitting is correct what else could it possibly be but an internal problem? If you've removed the front line and nothing comes out, it has to be the wrong fitting in front or something internal. You've removed everything external.

 

Yeah, that's what I figured, but it never hurts to confirm. I appreciate the assistance.

 

Howdy Mark. Since you seem to be the local auto guru, I figured I would pose this to you rather than starting a new thread. I done goofed. With Christmas and after Christmas work craziness (I'm a contractor) I never nailed down my issue, just put it off and drove it. I figured that if it was shifting normally I'd be good to go, at least until I could lay by the money for a rebuild or built unit. Today I learned how wrong I was. Truck suddenly lost all acceleration as I was driving. If I really juiced it I could get it to move forward slightly, and reverse was a little better. Paid 200 bucks for a tow home.

When I shift gears I can feel it clunk into drive or reverse, but it produces no motion. 1 and 2 behave the same as drive. If I put it in drive it will roll forward, and if I put it in reverse I'll stay put (My driveway is on a slight downward grade as the truck faces). In the 3 hours I've spent googling I have heard everything from bad forward clutches, to the brand new MLPS somehow causing this, to the diff. After paying a few k for this truck recently, I dont really have the cash to pay the 2k a rebuild was running.

What steps would you recommend to diagnose exactly what part has broken, and if you could point me towards any good walkthroughs I would appreciate it. At this point I'm willing to try rebuilding it myself, but from what I've found it requires specialized tools and the tolerances have to be JUST right.

 

It isn't any sensor or anything electrical. It's broken. The only accurate way to diagnose exactly what broke is to take the trans out and tear it down. You can et a very good rebuild manual at Automatic Transmission Service Group.

You could put a pressure gauge in the test port. That would determine if it's the pump or not. Either way, the trans has to come out and get torn down.

Driving a transmission that has problems almost always leads to a total failure.

 

Yeah that's kindve what I figured. Teach me to act like a fool. There isn't a chance I'm going to try to fix it myself, it just irks me that I dont have the faintest idea what went wrong. I dont know what would cause a transmission to just barely move when you gun it. I've had friends and family who broke a part and it was completely dead in the water, every time. Oh well. Thanks for all the help, both in this post and in all the posts I've seen you pop up in for trans related issues.