Searched several times over the winter.
Finally tore each hose out one at a time and went carefully over it before returning or replacing.

Turned out to be the long formed semi flexible vac. hose that runs from the gas fumes purge tank control valve group to the throttle body across the top of the engine. Ripped it out, on one of the bends was a small crack all the way thru, apparently would open up wide when stressed and cause problems. Mainly on hill pulls or hard acceleration but not every time. NO hair left after this one.

Replaced, deleted the codes. Runs like a top.
Still amazed at how much power these 4.0L V6 OHV Fords have from low speed on an uphill on ramp drag race.
stirs the old hot rodder blood

 

I've heard the 4.0 liter Extended Aerostars are not as reliable as the 3.0 liter Short Aerostars.

 

You heard wrong. The 3.0L and the 4.0L have different issues, both are reliable. The 4.0L biggest issues is certain years have heads that will crack if the engine leans out due to vacuum leaks or plugged injectors. The '97 heads are crack resistant. The other problem is the valve seats can wear down and recede resulting in a low compression issue. Again, this problem is more prevalent on higher mileage engines that have had lean issues.

The 3.0L its major problems are that it is undersized and underpowered, which results in a greater stress on the motor. Combine this with the smaller lighter duty radiator, and the result is that the 3.0L is more likely to overheat. The 3.0L also gets coupled with a lighter duty version of the transmission, so even though its under less torque, it still has to deal with the weight of the vehicle.

I've owned several 4.0Ls and a 3.0L. The 3.0L was far less reliable than the 4.0L in my own experience, mostly cooling system issues not eh 3.0L. The 3.0L I had was also TFI and it used a distributor. The 4.0L uses coil packs which are far more reliable than distributors. I replaced the distributor twice in the 200,000 miles we ran the 3.0L, and the coil three times. I have only ever need to replace the coil pack on my 4.0L once per vehicle.

Both motors are equally likely to have a blown head gasket, maintenance is key there. All in all, I'd take another 4.0L, the 3.0L was just underpowered. I mean really, it produced just 150 hp and not a lot of torque and it was still a heavy cast iron anchor. At least the 4.0L has tons of torque, especially low down in the power band to offset its weight.

 

That's great! Now you don't suck anymore!!!!! Sorry, I've been inhaling too much smoke lately.

 

i deserved that after the greased piston jokes.

hows that new engine running?

like greased lightning? sorry, couldn't help myself

 

I'm loving the "new" (rebuilt) engine...so quiet and smooth. Still waiting for the mileage to improve. Rings must not be seated yet.....dang grease! Maybe I 'smoked' them too much!! Been fussing with the tranny since rebuild. Wish I never put that shift kit in. All good except harsh 2-3 shift. I think the shift kit is for older trannies. 90-91 E4wd versions worked perfectly fine. Installed the kit in hopes to solve the reverse engagement clunk. I don't know if the resolved clunk is due to newer reverse servo or the shift kit....or both. Anyhow, life is good again........and no leaks!

 

You do realize shift kits need to be calibrated right? I'd rather take a harsh shift over slippage any day.

The harsh 2-3 shift is caused by the difference in ratios between 2 and 3. This is a large part of why Ford switched to the 5 speed auto later on. Also, some of the hardness can be caused by excessive clearance between components, what internal parts did you replace or check?

 

I'm not certain I understand what you mean by calibration. There is no such term utilized in the several rebuild manuals or online rebuild diaries.

There was no harsh 2-3 shift with the original transmission. I have the much touted adjustable vacuum modulator I'm still playing with, not much success with that so far.

This was a master kit rebuild, frictions,steels,bands,bearings,thrust washers,shells and races. All clearances were checked during assembly and all were within factory spec as to end play, clutch pack gaps, etc. I followed the shift kit (Transgo A4LD Jr) instructions as to spring replacements, adding a 5th check ball and increasing separator plate openings and creating an oil passage. The 2-3 is not bad when starting out cold but harshness increases as the tranny warms up. Its liveable but I know it was very smooth before the rebuild.

 

are you sure you're getting sufficient vacuum to the vac. mod.?

hose or connector damage. engine not producing sufficient vacuum yet?

vac. mod. not working correctly?

I've found that shift kits always make the upshifts too hard for my tastes. they change the timing between band release>clutch pack engagement shorting to point where one may still be partially engaged while the other is going into engagement. opposing forces.

there is a whole test section in the Ford DVD on the A4LD testing the vac. modulator, vac. line, and vac. mod. controlled up/down shift section in tranny

Shift speed table from manual

Axle Ratio 3.73 N/V = 49.5
Throttle Position Drive Range Shift km/h (mph)
Closed Throttle (D), D 3-2 18-25 (11-16)
(D), D 2-1 10-18 (6-11)
Minimum Throttle a (D), D 1-2 18-24 (11-15)
(D), D 2-3 25-35 (16-22)
(D) 3-4 — (—)
Part Throttle b (D), D 1-2 37-45 (23-28)
(D), D 2-3 57-65 (36-41)
(D) c 3-2 47-54 (29-34)
Wide Open Throttle d (D), D 1-2 56-63 (35-39)
(WOT) (D), D 2-3 96-103 (59-64)
(D), D 3-2 89-97 (55-60)
(D), D 3-1, 2-1 44-52 (27-33)
Manual Pull-Down 1 2-1 37-52 (24-33)


a Minimum throttle shift speeds 12.0-15.0 in-Hg. Minimum throttle 3-4 shift speeds electronic and determined by engine calibration.
b Part throttle 1-2, and 2-3 shift speeds @ 2 .0 in-Hg. Part throttle 3-4 shift speeds electronic.
c Part throttle 3-2 shift speeds 1.0 in-Hg.
d Wide open throttle shift speeds 1.0 in-Hg.

if all else fails and you don't want to pull tranny?
i'd try switching to a lower viscosity ATF such as the new Dexron VI.

good luck
cliff

 

I think you are fine then. The smoothness of the stock is caused by slippage. The original trans is designed to slip at shifts to make the shifts and seamless as possible, at the expense of heat and longevity.

As far as calibration, it is really beyond most DIYer so it is not mentioned in DIYer articles. Outside experienced transmission tech, you will never hear about the valve body adjustments and calibrations. I work closely with a transmission shop, and they have a great builder who knows about such things. He is quite good at making the small adjustments that control the final outcome. My '96 Taurus doesn't have a shift kit or a tuner, but due to some valve body calibrations, it shifts like it does. It has 170,000 miles on the original trans. I bought it from an old Grandpa who lost his driving privileges, and when I bought it with 138,000 miles, it had a flashing OD light, meaning it had transmission issues. They recalibrated the valve body to increase line pressure, and even without a proper shift kit, the trans is still going strong.

Even with the harshness you report, I think thats really quite ideal. The motoring public thinks that smoother shifts are better, and to them its all about feel, but all too many people wonder why transmissions these days cost so much. Its because they have to have lots of friction surfaces to shed material from. They are designed to be sacrificial to accommodate comfort.

All the shift kits I have had were Sonnax. I once asked my shop about the Transgo kits, they told me they are good, but that the Sonnax kits tend to be more controllable and smooth. Transgo kits are better suited to DIYer and high end race applications when smoothness is not as important as solid engagement.

 

Thanks Cliff and KhanT for the detailed and thoughtful explanations. Other than the 2-3 issue the tranny shifts very nicely. I'm thinking it is just due to increased line pressure by the modifications. If I drive like an old lady there is hardly any detectable shift harshness. The shift kit instructions say intermediate band adjustment is critical for proper 2-3 shift. They say adjust band down to where you can just turn the output shaft by hand then back off only 3/4 turn. Once installed, I can't do this with the 4wdr with its internal differential. I tried turning the band adjuster to just 1 turn out instead of 2 but there was no difference in shift feel so I returned the adjustment to factory specified 2 turns out.
Thanks for the responses. Nice to know we have some excellent help available on the forum.

 

What codes were you getting?

 

I don't remember from 1 day to the next what the wife told me anymore. remember a code? no chance.
one of the purge system ones. also a lean code maybe.