I think any transmission they thro at it will do the same thing, doing what comes naturely. The OP didn’t say it was burned up.
Read the title of the thread. The original was burned up. The transmission shop obviously saw a problem because they threw a second rebuilt unit in there. No it’s not doing what comes naturally, it needs to be properly diagnosed. Awaiting on OP
transman
OK, I missed that in the title. He never mentioned it in the post. Was the 2nd and 3rd burned up allso? Just what was burned? I let my brother drive my New van back in '96 and he was on and off the gas so much that it was shifting on level ground on the interstate. After that I never let him drive it again. But it was still doing it’s job at 138K when I traded it in.
Any transmissions they put in it will (probably) shift up and down on the freeway because it is overloaded and
the OP probably drives like my brother.
Quote "The transmission shop obviously saw a problem because they threw a second rebuilt unit in there"
NO, the shop saw a great oportunity to sell a rebuilt transmission!!
The first one was burned up so obviously it needed to be replaced. Shop put rebuilt unit in it. Rebuilt was still hunting so shop puts in another rebuilt unit. No great opportunity there, they did it on their own dime. If the unit was just doing what they normally do, they wouldn’t have put the second rebuilt unit in it.
transman
I’m also having a near impossible seeing the transmission being at fault. Maybe the first time around but not 3 times in a row. That thing is 22 years old with pretty low mileage and that could mean it’s been sitting a lot.
Someone is going to have egg on their face if it turns out that pack rats have decided to build a residence in the exhaust system or the air cleaner housing. 
Since it’s claimed that these transmissions are Ford rebuilt units I would assume any updates or modifications were done at the reman facility. I wonder what Ford has to say about this? I sure can’t see Ford providing multiple reman transmissions under warranty without digging deeper as to why this problem is repetitive.
Transman you said "Problem here is that 2 different rebuilt units have been installed both with the same symptoms as the original. " The problem was it kept shifting up and down, a very normal thing to do with a heavy load and an old, underpowered engine. So far OP has not said what size engine it has but I’ll bet it is underpowered. Someone on here said it was probably a 5.8 Liter. That figures between 354 to 360 CID. A 360 Ford was never very whoopy.
Like I said before, the first trans was hunting and burned up. It needed to be replaced, thats a given. Trans shop replaced original with a trans from Ford, same issue. This should of been a hint for the trans guy to do some diagnosis (drivability and trans) Hunting is not, and I repeat NOT normal. There is a difference between a transmission downshifting due to road conditions and “Hunting”. Hunting can be caused by electronic issues AND mechanical transmission issues. Since the rebuilt is hunting like the original burned up transmission, I would focus on an electronic problem or an engine “Drivability” issue. Like I said earlier, a scanner needs to be connected. Live data can be your friend when diagnosing transmission issues. I dont think the trans guy is trying to get over on the OP at all. The OP is definitely going to pay for the replacement of the burned up transmission, that is to be expected. The shop isnt going to charge him for the second replacement trans. The trans guy is throwing things at this vehicle hoping it will cure it when in fact, he needs to do some basic diagnosis.
transman
Does the truck have an rpm gauge ? Do you know what the final drive in OD is and what the power output of the motor is at that rpm. Is that 200 hp figure with comparable low torque for towing a Winnie a reasonable expectation. Doing the math is a heck of a lot cheaper then replacing transmissions and why transman618 makes a lot of sense.
Quote by Transman “Like I said before, the first trans was hunting and burned up. It needed to be replaced, thats a given”.
I don’t see how it is a “given” when the OP said “It has a manual button for turning off the Overdrive and when I do this, it stops jerking and drives smooth.”
Let me provide a little more information. The “in and out of overdrive” symptom happens on a perfectly flat road; no uphill or downhill involved. When I first experienced the problem, I thought it was bad fuel. Chug a lug was the feeling as I drove 55 miles per hour down the road (60 is the fastest I drive it.) By default, this vehicle has the Overdrive available. There is a manual button that allows me to turn off the Overdrive. I did this and the chug a lug symptom went away. As I drove down this flat highway, I pressed the button on and off to test to see if the problem was indeed the Overdrive. It was. This engine has 56k miles on it and appears to run great. I took it to the mechanic who told me that the problem was just the Overdrive switch. I said “great, but please check out the transmission too.” He did and told me that it was damaged. So on the first visit to the mechanic, he replaced the switch and installed the warrantied Ford rebuilt transmission. I took it on a trip and it was fine. I took it on the second trip and it failed again. I did not realize that allowing it to chug a lug would result in burning out the transmission but it did. On the second trip to the mechanic, he put in a new rebuilt Ford transmission, a new Overdrive switch, replaced the fuel sensor, and he inspected the wiring. This did not resolve the problem so he sent the onboard computer (PCM I believe) to Ford to have it tested and “rebuilt” whatever that means. The mechanic has been in communication with Ford about this problem and has done all that they suggested to no avail. So, it is true that I can just turn off the switch and drive the vehicle without the Overdrive. The difference in gas mileage is significant though; about 2 to 4 miles per gallon. I know that when this vehicle was new, this problem could not have behaved like this or everyone who owned one would have burned out their transmission on the second trip. I am wondering if kawasaga is on the right track with their being a possibility that the PCM was not upgraded along with the rebuilt transmission? Or, does PCM come with the rebuilt? It seems to me that this problem should have a solution and that Ford should know what the solution is. Many Minnie Winnie’s have been sold with a Ford E350 chassis. Thanks for the comments and if there is any one thing that I should tell my mechanic that might lead him in the right direction, please let me know.
P.S. My mechanic says that his scanner software will not work with my Ford as it is too old.
transman618, do you think there is any advantage to my taking this directly to Ford?
Marworth, I’m not familiar with where you are but you really need to have a good drivability guy check out the engine side of this vehicle. Simple things like a misfire, a TPS problem or other sensors could be causing the transmission “Hunting” issue. From what I have been reading and correct me if I’m wrong, you have had 3 different transmissions (The original, and 2 Ford rebuilts) doing the exact same thing. It sounds to me like something electronic which controls the shifting, either on the engine or transmission side has a problem and is causing the hunting between 3rd and 4th. Someone with a good scanner which can monitor transmission function can see whether and when the computer is “Commanding” the shifting or not.
And Ellis, The transmission was burned up and needed to be replaced. How can that NOT be a given. A vehicle will not operate with a burned up transmission. Do us a favor, PLEASE dont give transmission advice, you do not know what you are talking about and are giving bad information. I applaud you in your 63 years of driving and hope that I am still driving along for the next 33 years or more. Please stick to what you know.
transman
Quote"A vehicle will not operate with a burned up transmission." Transman
The OP said that with the overdrive OFF it drove fine. How can that be with a “burned up” transmission.
I read that too. If overdrive is burned up, it wont operate or operate properly I should say. Drop it to 3rd and get it to a shop. The transmission is intended to have 4 gears. You dont just lock out o/d forever like some people I know will do. Theres folks out there that would run it in reverse if all their forward gears went out. Bottom line is, it looks like something other than the transmission is the culprit. Yhis is not a normal condition and it needs to be fixed.
transman
Theres folks out there that would run it in reverse if all their forward gears went out.
Or other reasons…
I just cannot believe that 3 transmissions in a row are all suffering the same problem. The first one, maybe, but to think the 2 remanufactured from Ford units are also suffering from the same problem is a real stretch of the imagination.
It appears an independent may be doing the work and that also raises the question for me as to how and why in the world FOMOCO would be involved this deep on a 20+ year old motor home and would provide repeated reman transmissions without someone asking why. A parts warranty only goes so far.
This was apparently described at first as what appears to be a transmission gear hunt. The last post references a “chug a lug” and the point could be made that those 2 are not one and the same.
Chug a lug could be a fuel pump dragging down now and then and raises the question of whether this vehcle still has the original fuel filter in place.
Age, low miles, sitting for extended spells, and so on can be tough on not just the pump but the filter also. Any moisture in the fuel system settles into the lowest part of the system and that’s often the filter. It then starts to rust the screen in the filter and the partially clogged filter then takes a toll on the pump.
Who knows, maybe there’s half a cup of water sloshing around in the tank and now and then it just happens to hit the pump pickup… 
Well, obviously, the tranmission is not the problem.
I drove it today and with overdrive on this hunting for a gear even happens at 5-10 mph. Since the first new rebuilt we knew the problem was not the transmission but something else. With overdrive off the shifting is smooth. This leads us to believe that the engine has plenty of power, and the transmission is working properly without overdrive on. It certainly appears to be an electronic problem.
We live in Monterey, CA and the closest mechanic we could find willing to work on it is 70 miles away. Not sure how to find someone who has the diagnostic software to test our Minnie. I’d be willing to drive a couple of hundred miles to find someone if it the person could discover the problem.
I don’t know this vehicle or its drivetrain. But its probably got a throttle position sensor and a MAF sensor. There’s also likely to be a speed sensor or two. Someone around where you live has to be able to access the data for these. You can actually do a basic check of each with nothing but a multi-meter, although those checks won’t be perfect. I mention those things because they are the kinds of things that are likely to send the transmission funky info. Putting a vacuum gauge on it wouldn’t hurt either.