Well over christmas I lost my overdrive. One the truck shifts into 4th (OD) it basically goes to neutral. After doing some research on the site I found that this problem is not unheard of. Symptoms are; No over drive, just shift right into neutral; no engine braking when shifted into 2nd; and if you turn off O/D then you can drive normal with the first three gears.

I dropped the trans pan and there was nothing in it. I dropped the valve body and thats where I found the problem. The overdrive servo retaining clip snap and lodged itself into a valve in the valve body. I have bought the new clip but I have not reassembled everything. Will update when complete.

Here is the valve body removed and where I found the first broken piece


Pic of the other broken piece stuck in one of the spool valves


piece stuck again


Spot where the servo vale is positioned in the trans


this is the servo removed with the pieces of the broken clip

 

I thought that I had the same issue with a broken OD Servo ring, but it was intact after we took it apart.

I have heard of the same symptoms (Overdrive neutral, no 2nd gear engine brake) caused by a worn OD Servo Regulator Boost Valve and Spring. Any thoughts on this or what I should look for next?

The only code was "Incorrect Gear Ratio" so it seems the electrical is working fine.

Thanks.

 

I thought I have read the same thing on this forum but i can't be sure how accurate that info is.

This is also has been posted http://www.sonnax.com/system/announcement/76948-29K.pdf

This issue is supposedly from a burned up OD band. I don;t have direct experience with this though.

 

@tim98 - How hard was this fix? Approximately how much was the part and could someone who isn't a mechanic, but fairly handy do this repair? I've replaced my own spark plugs, injectors, coils, lower ball joints, battery, FPDM and fuel filter. My upper control arms were done at a mechanic shop, but that was more for lack of time to do the job.

Anyway, we just lost OD on the truck, today, so your post is very timely. Let us know if this fix worked for you, please.

Cheers,

 

The retaining ring was $2.44 at my local ford dealer. The part number is F2VY7384B.

I have not actually completed the job yet. Its still apart in my garage because I have not had time to reassemble it.

Here is the thing about this fix. One, you have to remove the valve body assembly. This is not difficult and does not require special tools but there are about 24 bolts and some must be put back in the same location due to length of the bolt. You also have to remove the solenoid valves, bridge connector, and shift lever detent spring. Again not difficult but small parts that can be a pain if you do not remember how they get reassembled.

Once the valve body comes off you have to be careful of the gasket assembly which has to come off. In the first picture you can see where those two top plates have to come off plus there is another bolt or two that comes off to get to the valve body oil galllies.

Once that gasket comes off I was able to find the spool valve that was jammed with the broken piece of clip. You also have to be really careful because in those oil gallies there are small plastic check ***** that are in certain location. You DO NOT want theses to be removed from their spot because there is no way by looking at the assembly to figure out where they go back too.

The next part will be the most difficult part. You must remove the old clip that holds in the over drive servo but since one end is broke you cannot use snap ring pliers. It must be very carefully pried out using a pick and screw driver. It has to be done with scoring or gouging the aluminum transmission casing. There is also spring pressure behind that valve so it makes it more difficult. You will also need to find a way to slightly compress the valve when re installing it.

So other than the snap ring pliers and compressing the valve its pretty straight forward but I would make sure you have a tech resource or take pictures of the disassembly. If you damage the valve body of worse the area the valve body bolts to the transmission its going to be an expensive repair.
I'll let you know the results when I put it all back together

 

Awesome! Thanks for all that. I found a PDF assembly/disassembly instruction manual. [Here] and [Here]. From the diagrams I have found:

 

I found a bottle jack to be useful here. I put the snap ring around the shaft of the jack, and used a pick/screw driver to hold the overdrive band into position via a detent/hole in the band, and jacked up the servo to clear the snap ring groove, and put snap ring in and release the jack.

We have : One hand holding the band into position, and the other hand jacking; once there you can release the pick/screw driver, and use both hands to put in snap ring.

 

Alright, I definitely missed something here. Put everything back together but I still have the same issue. no overdrive and no engine break in 2nd gear

MLD, what did you mean you held the band into position? I just pushed the servo into place and installed the clip. I think i missed this. can you explain?

 

Mtylerb, those are fantastic tech instructions. Very similar to the ones I use on Mitchell on demand. Great find. Are you going to attempt taking it apart?

 

Oh man. Drop the valve body, and find the slot to access the band. You will see it with a hole in it. Put an angled pick in the hole in the band, and slide it over as far as you can. Then push servo up just to clear the snap ring slot.
The servo will engage the tang on the band, but you will not be able to see this. The 'sign' that you have engaged the band with the servo, is that it won't snap back out of position. If it snaps back then retry. It may take several practices.

 

MLD, Thanks for the explanation. Currently its all assembled so I am going to have tear it apart agin when I have time. I am not sure which hole you are referring to but once I get it apart then I'll have to find it.

 

Tim, I copied your picture.

Look at the 10-11 O'clock at the overdrive servo bay. It's square, and this is your access.

Poke a screw driver in there, and you cant miss the band. It will flex and it will have a small hole in the band itself, so you can move it.

 

Awesome. That gives me a great place to start. will let you know when I break it down again. Thanks

 

Eventually. I'm just driving with O/D off, for now. Well, rather the other half is driving with O/D off. She does less driving than I do in a day. Mileage sucks, but I don't believe it's doing anymore damage. I need to wait for it to warm up a bit. It's -45*C outside (-49*F) and the only garage I have that's tall enough to put the truck up on a stand, isn't heated.

 

Update

Well after tearing it apart twice and some valuable help from MLD and Darrin its finally fixed. As MLD stated I forgot to engage the OD band onto the point of the OD Servo shaft. Since I had problems with it I figure I would take some pics for other people to reference.

This pic shows the access hole to the overdrive band. You can see the small hole in the band itself. This is where I used a pic to slide the band toward the servo.




This pic shows where the detent or slot of the overdrive band is. You can't see it but I have the pic in the hole of the overdrive band pushing it over. This is where you have to be able to slide the band over, hold it, and try to raise the servo into position to catch the band detent. It took a couple of trys but eventually got it. Slapped everything back together and I now have overdrive again. Thanks for everyones help.