I am working on a 1997 explorer, 1st gear will not engage. Put it in D and you can feel it engage but it will not move. Put it in 1st manually and still nothing. Put it in 2nd and it engages and drives, while driving in 2nd you can put it in OD and it shifts fine. If you stop, you have to start in 2nd again to get it to move. Reverse works good, NO !st gear...I dropped the pan,it was clean, no chunks or metal. Dropped valve body and gasket is not blown. All valves seem free and ohm tests are good on solenoids. Is the problem from a broken rear drum reverse sprag one way clutch? I am open to any other suggestions on where to go next.

 

Not to worry, i did so much warranty work on these, I wish I could forget about them.
If this trans doesn't work in first gear (in D range), and if I'm reading correctly, it still doesn't engage in manual 1, the problem is concerned with applying the forward clutch and the low/reverse one way clutch/band.
Now, here's the rest: does it shift 2-3-4 if started off in 2nd? It really doesn't matter, because if it does move in 2nd (and ANY other forward gear), the forward clutch is appllied. And, along other lines, it doesn't matter about the low reverse one way clutch or band; at the very least, the L/R band is working due to the fact that Reverse gear seems unaffected.
This little lesson in application has a point, which is, what do you need to move (automatically) in D and 1? The forward clutch is what's (most likely) trying to apply, but it won't correctly due to a pressure loss.
The odd thing is, the pressure loss is NOT throuh the application circut, by which I mean that if the truck starts moving in 2-3-4, but not first, the forward clutch is working fine, as if it wasn't, you'd still be sitting at the stoplight wondering why you're NOT moving. This means that the case, pump/stator support, and sealing rings are working fine. So, what's left?
The valve body must be the problem And I know I'm right, becuase I'll demostrate a problem I had with an identical unit ('97 Xploder, 4.0L SOHC, 5R series trans). The car was purchased inexpensively, owing to the fact that reverse didn't work. THe trans was removed, the broken reverse band was replaced, the unit thrown back in and the unit test driven. The unit shifted 1-4 perfectly, and so did reverse, the ONLY problem with said unit is that it doesn't have engine braking in man 1 (in which, the forward clutch and L/R band is applied). So, the L/R band wasn't applying. The customer was happy with what he had, and went away.
THese valve bodies were a pain, and the only real common problems was with the seperator plate gasket, which you mentioned was good. The other problem I saw was the EPC solenoid would leak.
These valve bodies (once the sep. plate is removed) are relatively easy to clean and dissasemble, but they are full of little pins and stops that always fall out and never seem to get found.
The best advice I can give you is to use a large area where you can drain it, take it apart, and spread everything out. If you can, drain it thourogly, take off the plate, and take about a million pictures of the pins and stop that are strung out in this body, and once secure in this knowledge, make very, very sure that no valves are stuck, no springs are broken, and the valves display NO wear (no shiny score marks or large scrapes). I'll be the problem is in the right lower end of the body, in the form of a stuck valve. Of course, I'm not there, and I've been called a hack.
If you do uncover something of the sort, it would probably be best to replace the body if the valves are hanging up. Most trans rebuilding suppliers would carry or at least be able to get it. Please make sure to use a torque wrench to reinstall it.
By the way, I havne't ever gotten around to fixing the other exploder I mentioned. As I own it, it doesn't seem that important for me to devote an afternoon of time to repairing it.
Let me know.

 

today I took my valve body apart. Hope it still works. Found a web sit called sonnax, showed breakdown of valve body. I am sure I put it together correctly. I am waiting for new gaskets. Had a hard time getting some valves out. They were not stuck till I tried to get them out. Coast clutch valve, converter reg valve were not sticking but I could not get it out of bore, so I left it alone.EPCBoost valve& forward modulation valve seemed stuck.About half of those valves were a bear to get out of bores. Thanks Greasemark for your help. Keep looking for my next post, probably be next week after gaskets get here. Wish I could test valve body before I install it!

 

I know exactly what you're saying about testing it; that's the part of this job that stinks, as you just need to have the intestinal fortitude to just DO it, and trust yourself.
Usually, if the valves (especially the EPC boost) was stuck, it's time for a new body; they can easily warp if not installed correctly (if not tightened with a torque wrench). One of the problems that they can display is something exactly like this, but you'll never see the problem as once the torque is relieved in the removal process, everything snaps back into place.
About the only valve in this trans that used to stick really bad was the trans cooler circut valve; and just about any shift kit you get with this trans will have you either put another spring in or put in a modified valve that lets fluid flow to the cooler all the time.
Please let us know what's going on.

 

I installed valve body after I went over all but one valve. I was not able to get it out. I believe valve body is wore out. All valves seemed to have a ridge to get past, like a ridge on a piston bore on a motor. Right now I still have good reverse, Put it in 1 and it grabs but slips when you gas on it. 2 slips even more and also drive. Just go to drive from park and it barley engages. Do you think its still valve body? I do, need more advice. Try a rebuilt valve body?

 

Ok, this is now worrisome. Did this trans slip (in any other gear) before? I don't remember hearing this before, but I could be wrong.
At this point, there are a couple of things to do; I'd start with a line pressure test, just to make sure that you have a good pump. If ok, then I'd remove the valve body (again), let it drip, and do an air pressure test (20 psi, no more, no less) on the forward, high/reverse, and O/D clutches and bands, just to make sure that all is good and there are no leaks.
Another thing to check that is easily overlooked is the flatness of the valve body and case where they bolt together; it's easy to warp the passages, then you're left with a problem like this.
Please let me know what's up. I'll keep an eye out.

 

I ordered a rebuilt valve body, waiting on! How do you do a line pressure test, and how do you do test with air to check clutches?

 

Forgot to say...It had no slipping before I redid valves. Originally had no 1st, had 2nd 3rd and od. No slipping...Now after I took springs and plungers out of valve body, cleaned them up and reinstalled them I have 1st, but small slip in 1st, slip gets worse as gears go up. Did not drive it like that for more than a minutes, did not want to burn up clutches. I also put new gaskets on for valve body. Like I said waiting on rebuilt valve body.

 

Installed new valve body, back to square one. It is the same as when I started. Put it in drive, you can feel it engage but you have almost nothing. put it in low, 1st and it slips feels like half engaged, put it in 2nd and you take off like normal, no slip good engage. While driving in 2nd you can put it in drive and it works fine, overdrive and all. As soon as you stop you have nothing until you go back to 2nd manually, get it rolling and put it in drive and she works fine. I have a strong reverse, no slipping engages right away. Now where do I go from here. I have rebuilt a few transmissions and have been lucky so far. Im not scared to tear it apart. Strong reverse and strong 2nd

 

Could you have a one-way clutch that went south?