1991 Ford Ranger - Lots of Miles. A4LD Transmision problems (what else is new)?

[Phil Shepherd]

Hey all, I am new to the site, but have been getting advice from this site on fixing my '91 Ranger's transmission for several weeks now. Special thanks to BrooklynBay -

I have seen several posts similar to the problems I am having, but I think I can narrow down the problem by what I have already accomplished.

First, the truck has 267k miles on it. Yep, over a quarter of a million, and the engine still runs like the day I bought it from my uncle with a scant 140k on it. No smoke, no oil burning, everything works. This 4 liter V-6 ranks up there as one of the best engine I have ever had in a vehicle.

The transmission is another story - an A4LD, with all the apparent problems. In the last several weeks it has started to hang up between 1st and 2nd gear, with the engine going to almost 4k RPM before shifting, unless I completely take my foot off the gas pedal and vacumn increases enough to pull it in gear, and then it will slowly slide into 2nd. 2nd to Drive is a bit slow too.

I can SHIFT MANUALLY into 2nd and it shifts right into gear. As a matter of fact, shifting gears manually allows the truck to shift into every gear with no apparent difficulties. Also, once into drive and overdrive (on the highway) it shifts just fine - going into overdrive, and downshifting to drive when I accelerate without manual shifting.

What I have worked on so far:
I replaced the fluid and filter.
I replaced the vacumn modulator. I know some of these are adjustable, but I did not find any adjustment on it. I was told by someone that the adjustment is inside of the barrel where one of the vacumn hoses connect. Is this true, and can the lack of adjustment be part of the problem? After these repairs, it is still not shifting properly, and as previously described.

In order to replace the modulator valve, I had to remove the seats and carpet inside the truck to get to the removable plate covering the modulator valve. I have pictures if anyone is interested. It is not something I'd want to do again if I can avoid it. Also, as the truck has got a lot of miles on it, and the value of the vehicle is basically the cost of a rebuild or less, I don't see a major transmission overhaul as something that makes sense financially on this truck.

Hope that's not too much for a first post!

Thanks -
Phil.

 

[BrooklynBay]

Welcome to this forum! I've moved your thread to the Ranger section. The 1-2 shift delay could be related to a sticky governor, broken or misadjusted intermediate band or an internal valve body problem. Did you find any parts in the pan when you replaced the fluid & filter?

 

[Phil Shepherd]

BrooklynBay - Thanks. No parts in the pan, although the residue in the fluid looked like it had a black rubbery residue in the bottom of the pan - no metal on the magnet. I didn't like the look of the fluid, but it had been a while since it had been changed (over 60k miles, probably).

I want to also add that the transmission shifts normally until engine temperature starts to get into normal range. It doesn't take long before the transmission starts to hold in lower gears, but for the first 5 minutes of drive time, it shifts properly through all four gears. As the engine warms, the shift point for the 1 to 2 gear change gradually (but quickly) increases until reaching over 4k engine RPM.

Like I said, 267k miles - do you think it is repairable without having to be overhauled?

Thanks Again -
Phil.

 

[BrooklynBay]

Check the valve body gaskets. It's possible that the servos are dried out, and leaking.

 

[Phil Shepherd]

I have had the pan off, and changed the filter, but have no experience with the valve body - do you have a link and any pics (if available) posted on line to show how this is done?

Thanks again -
Phil.

 

[BrooklynBay]

The sticky thread in the transmission section called the A4LD valve body rebuild diary has a lot of information. I have additional threads listed in my list of useful threads.

 

[Phil Shepherd]

A4LD Vacuum Modulator Adjustment -

The transmission in my Ford Ranger (4.0 V6, A4LD transmission) is shifting from 1-2 at too high an engine rpm. I have attempted to adjust the vacuum modulator with limited success.

I initially backed the adjustment screw out about 3 turns before (re)installing the valve, and I think I backed out the adjustment about 3 turns more once it was installed, although with it's location and difficulty to reach, I am not 100% sure I got turned the adjustment screw every time I attempted.

So that makes a total of 6 turns adjustment, and it only seemed to lower the shift point by about 500-700 rpm. As the truck runs now, I have to take the engine to about 3000 to 3200 rpm and then completely let off the accelerator before the transmission will shift from 1st to 2nd. It also drops into 1st gear at too high an engine rpm when below 20 mph.

Is this a very fine thread adjustment screw, requiring more counter-clockwise turns to lower the shift point further, or is there something else that might be causing the high 1-2 shift rpm? Shifts from 2nd to overdrive seem to be okay.

Thanks -
Phil.

 

[BrooklynBay]

It sounds more like the intermediate band is out of adjustment or broken. Another possibility is a sticking governor, but it sticks when it's cold.

 

[kallen924]

not trying to jack the thread but would a vacuum modulator cause a delay from take off? i have to rev up to about 1400 to 1500 to get it to go but then onces it goes its good and shifts through all the gears for the most part.

 

[BrooklynBay]

Check the vacuum line for leaking fluid.

 

[kallen924]

not leaking fluid anywhere, just changed oil and the car doesnt leak anything