Hey guys, got an 89 F-250 7.3, I was taking it out on the highway this evening to see if anything funny would happen after I was having problems with my starter today. I was doing 60km/hr, and it was running at 2000rpm. I punched it up to 70, and it was running at about 2200rpm. THEN I punched it up to 80km/hr and it was running 2500rpm, and finally I decided to giver up to 90km/hr and it was running 3000rpm.

Either the overdrive is not working or there is something preventing it from working. Is there a switch that turns the overdrive off? I couldnt find one, nor do I know if my truck even has one. Something funny is going on here, and I'm not sure what it is, but I'm planning on leaving town in a couple of months and I'm driving down, so I'd like to get this problem fixed.

What y'all think it might be?

 

I don't think you have an overdrive. Do you have a button on the end of the shifter? I remember the ODs not being standard until 90.

 

No dude I even think there is a button there, isn't there some sort of aftermarket product that you can get to give you overdrive?

 

So does anybody know how to hook up that overdrive kit?

 

The early E4OD overdrive trannies had the overdrive button below the dash, right hand side of the steering wheel. There is a square button with a yellow LED light above it that lights up if you push the button to shut the overdrive off. The light should also blink if you got tranny control problems.

Your 89' should have one of the first generation E4OD trannies.

The sure way to tell is your gear selector indicator should have a "D" inside and "O" where the older automatics (C6) only had the letter "D".

Another way to tell if you got an E4OD is to look on the drivers side of your IP throttle shaft. The old C6 had a Vacuum control unit with some hoses comming out of it. The E4OD has a little black throttle position sensor that has three wires comming out of it.

If your truck is an 89 it should have an E4OD tranny, although the older non-OD trannies were still available if you special ordered them.

At 3000rpm doing 90km/hr your are in 3rd gear (not O.D.) and your torque converter is most likely not locked either.

Can you get all of your gears when you shift manually using the shift lever.

If the truck is in Limp Mode you will not be able to manually downshift to 1st gear. You will only be able to select 2nd and 3rd.

It almost sounds like your E4OD is running in limp mode. Does the truck down-shift automatically when accelerating?

What gear is the truck in when you accelerate?. In limp mode the truck tries to accelerate in 3rd gear. It will feel like you have no power as the tranny won't let the engine speed up to produce power.

Hope this helps a little,


Sebastian.

 

No seb, theres absolutely no problems at all with the tranny. It shifts very smoothly into each gear, you dont even notice it shifting at all. I'm pretty sure its got the D inside the O, but I'll double check to make sure though. And if it doesnt have that, would I mostlikely have the C6 transmission?

The truck is definately not in limp mode because I got stuck a couple weeks ago and I put it in 1st and it worked. My little red thing inside the gear selector is broken and doesnt slide when I change positions, so sometimes I'd be in 2nd without knowing it thinking that I was in 3rd. So I guess that answers the question about limp mode.

If I don't have the overdrive, is there some sort of auxiliary unit that i can buy so that I can get an extra gear or two?

 

There are aftermarket Overdrive units but very few guys have them as they are very expensive. We are taking $3,000 to $5,000. I looked at them all a while back and concluded that I just don't want to fork out that kind of cash and it does not sound like you are prepared for that either. Converting to an E4OD tranny is expensive too and I don't know of anybody who has done it due to cost, complicated electronics and the E4OD being not the greatest of trannies in the first place.


If you do not have an E4OD tranny and 4:10 gears the rpm's you are running are about right I am afraid. Must be pretty noise driving at 3,000 rpm. Fuel Economy on the highway is probalby not to great either.



Seb...

 

if you have a c-6 the rans pan will be almost square and flat on the bottom with a modulator on pass. side rear beside the tail housing. An E4OD's pan is more rectangular with variations of depth.

 

Ok so I checked it out tonight, turns out there the D isnt inside an O. There's just a small dash underneath the D, thats all. So 3 grand for that eh...wouldn't it just be a better idea to get a tranny swap and get a different tranny that has the overdrive on it? I was driving an 86 F-250 7.3 this summer, and it seemed like the truck had over drive on it because I remember doing about 100k on the highway, and the rpms were around 2000. Although, the tranny was really ****ty and you had to back off on the gas to get it to shift properly. I'm guessing that tranny was an E40D tranny, based on you guys saying it was was really shi*ty tranny.

 

Would it be possible to get a tranny off of a dodge 2500 or 3500? Or would that require major modifications?

 

An add-on overdrive, an E40D (OD automatic) or a Dodge tranny - ANYTHING is do-able. It is just a function of how much money you have to spend on it.

Cheapest thing for you to do would be get some different gears in your axle. The 4.10s are what's killing you....

Probably swapping entire axle(s) with boneyard units will be the most economical way to go.

 

Ya man, I was thinking of going down to 3.55, but I like the raw power the truck has right now....i dunno, this thing is just to get me around town for now. I'll probably part with it when I get a dodge.

 

A,

Even if you are willing to put in the elbow grease to change to a secondary overdrive or an E4OD tranny, the cost just for parts usually make the whole thing un-economical.

The only way I can ever see this get done is if you had a wreck that you could salvage all the parts from.

See you on the mountains,


Seb.....

 

I had a GearVendor OD. It came on my Excursion when I bought it used from someone, the input shaft had some slack in it, and I wanted to put it on my 88, which has a C6. the input shaft was $650, then I had to have a tranny shop put it on, and that cost another $1500, so it was not economical even when I had the GearVendor already. When you add these costs to the $3000 of the Unit, its not worthwhile.
However, A 3.55 back end will have about the same effect, and you will not lose much bottom end either. Thats the way to go I believe

 

hmm...or should I look at those ZF5 trannys and see what they have?