91 trans will not start in o/d but will run in o/d

[ohiomike]

91 explorer w/ 4.0
my problem is if i try and start in o/d the truck wouldn't move. it clicks and if i rev. up it will rock alittle. now if i start in drive or any other gear it works fine, and going down the road above 50mph. and manual shift in o/d it revs. up acouple hundred rpms. but will shift in o/d. now if i come to a stop in o/d i will have nothing again. so i have to shift back to park then back to drive to go, or manually shift to drive before i get down below 45mph. then start out again and get up to speed then shift in o/d. It's almost like driving a automatic stick shift, down shift before every stop. I checked fluild level and going to change filter. just wondering if i need to do any work inside before i put new fluid in and then find i need to change solniod valve or anything else. any ideas will be helpful thank you for your help.
ohiomike

 

[Opera House]

Oou, oou, oou, I know this. This transmission has an OD One Way Clutch that works in the OD position. In the other positions there is the OD clutch (not to be confused with the OD band that gives you overdrive) that is engaged, taking the stress off (bypasses) the OD One Way Clutch. This is done so it shifts faster in and out of OD and is stronger in D. You have to pull the transmission apart, but fortunantly it is about the first thing you run into. You could go forever just manually switching between D and OD.betwen

 

[ohiomike]

so are you saying the trans needs clucth work inside the trans. and just as easy to get rebuild trans. to fix the problem.

 

[Opera House]

If you pull the transmission, it isn't any harder to remove the the eight bolts that mount the bellhousing to the main body to get at this clutch. No special tools are needed. Parts, manual, filter, gasket kit, and fluid would be about $100. Glacier has some pictures. I think it's easy, but no longer actively recommend people work on their own transmissions. I wouldn't put new tires on a 91, you can buy these running at auction for less than $500. You could have some fun and try it. Unfortunantly, most people don't have the logistics to do this. Try to get a transmission from a 94 with the improvements.

 

[FordLover]

I have a very similar problem.
When attempting to move forward, OD acts like a badly slipping clutch on a 5 speed, barely moves the Truck. So by shifting to Drive, it will shift normally, and at highway speeds I can shift to OD and it works great, settles down into OD with no problem. However If I floor the gas, it will rev to redline and not grab a gear, like it's in neutral. Once I slow down below 35 or so, it also acts like it's in neutral, but all I have to do is shift into drive and it will again act like normal.
This is on a 91 with ~156K miles

I'm certainly not in the mood to spend 1,500-2,000 on an automatic tranny, especially not for a truck I paid 800 bucks for.
Not real excited about pulling the t-case/tranny either, but I read all thru the Diary and was very impressed, and felt like I could actually work on an automatic.

 

[FordLover]

bump...mostly would just like to know if I'm going to do more damage by driving it in this condition...

 

[Glacier991]

I appreciate what Opera House is saying..... (I hold him in high esteem on these sorts of things) but part of why I did my "Rebuild it Yourself" series (the so called "Diary") was because a lot of decent explorers were gonna be junked because they were not worth a rebuilt trannie at shop prices.... SO, I respectfully disagree... if you have the inclination you can do it, and I'll make sure you have the tools available.

 

[FordLover]

I appreciate what Opera House is saying..... (I hold him in high esteem on these sorts of things) but part of why I did my "Rebuild it Yourself" series (the so called "Diary") was because a lot of decent explorers were gonna be junked because they were not worth a rebuilt trannie at shop prices.... SO, I respectfully disagree... if you have the inclination you can do it, and I'll make sure you have the tools available.

Your just about to talk me into it. My explorer is completely rust free, and a rust free 4x4 is difficult to find, even down here. I just can't see sending it to the junkyard for 4-500 bucks. I would be much more willing to do this if I'd had any experience before. I've worked on every automotive system (a/c, brakes, clutch, engines, manual tranny's, etc.) but never once even considered working on an Automatic. It will barely move the truck now, so I have no choice but to do something. I think the biggest hold back (after going thru the diary) was not having the specialty tools, and you've seemed to fix that problem!

Had you considered compiling a list of the places you got your new parts from, and perhaps even prices? That would be cool.
-Martin

 

[Glacier991]

I have meant to do just that... and had to move and a lot of the invoices and things are tucked away... I will make that a priority... others have asked too. Add that at the end of part 4. I have a few other things to add to the tool list... like proper external snap ring pliers and the Factory A4LD manual... and I need to come up with a "package" price for all that maybe. I am not wantint to make money helping on this... just make sure I am protected and the tools come home ok, and maybe help pay for the extra sets.

 

[Opera House]

Nothing ventured, nothing lost. You should consider a partial rebuild if there is no other major problem. I know the Tim Allen Syndrome is a powerfull force. Take down the transmission and you might as well do everything. My mission statement has been to encourage just repairs. A large number of problems happen only in the OD. Go beyond the center support and the possible mistakes that you can make increase dramatically. If you don't change the pump and front seal, you don't need any special tools. Replace the OD band because that becomes direction sensitive and develops cracks if its shape isn't maintained. Replace the OD star washer because splines wear into it, it does bend, it is cheap and it will bring back tolerances in this section. No need to replace the OD clutch because you never used it. Other than that replace what is needed. Don't touch the front seal or the pump. If these are fine they will likely stay that way. Polish where the seal rides. This will reduce it down to a simple two hour job. While you are at it replace the vacuum modulator, low/reverse O ring, and polish the speed governor. Don't touch the valve body. That will make it a good daily driver.