rebuilt a4ld no overdrive

[Hande]

What's this then?

Testing the OD solenoid with help of the lamp I didn't pay attention to one little detail: the OD solenoid gets energized also in D ! There's no change in
engine speed , no shifting felt in moving the shift lever from OD to D, but the
lamp stays on. Whether I ride in OD or D, the lamp goes on and off just the same. Also this morning my wife took the Ford to tow her horses with. She just called and said she thinks the engine braking is working - in D ! So here's the question: am I confused, is she confused or is it the computer that is confused?
I'll look at the pressures later today when she gets back. I got the gauge and a nifty little attachment to the tranny. This attachment has a valve in it so I can just plug the test hose in and out without having to remove the attachment.

 

[Hande]

The monologue continues...

Here then are the results of my pressure test:
Idle: P,N 65 psi, R 115 psi, OD,D,2,1, all 80 psi
Fast idle (@ 1200-1300) : P,N 65 psi, R 128 psi, OD,D,2,1, all 105 psi.
WOT forward speeds about 200 psi.
So to me these figures seem to be in line with what they should be. Fast idle R is on the low side, but the pressure would've risen had I kept the revs up. The WOT value is low, but that might be because when performing the fault-code readout the only fault code was 538, "insufficient rpm change during KOER Dynamic Response test". The WOT peak pressure only holds for a few seconds, then pressure comes slowly down to normal as road speed increases. I believe if the engine would pick up revs more quickly the pressure would also rise higher.
As to the dilemma in my previous post I think I got it figured out: there's no way for the computer to know which "gear" the speed selector is at, so the solenoid is activated regardless of the chosen speed. It is the hydraulic valves that then either prevent or allow the OD to engage, mainly the valve directly connected to the speed selector?
So I think this leaves me to open the valve assembly and dismantle and inspect every valve and passage in the assembly in hopes of finding something clogged or maladjusted.

 

[Hande]

..and still nothing...

So I took out the VB, went through all the valves. Some were a bit reluctant to come out, had to use pressurized air. The 3-4 shift solenoid didn't to me appear to be working properly, so I put in the original one. I had put in a solenoid kit in the fall with a 3-4 shift solenoid which is different from the
original. I think the kit was a Fitzall or something. Anyway this solenoid didn't seem to be working properly so in went the original, which seemed to work just fine. Ofcourse there is no way of knowing whether the solenoid really does what it is supposed to do inside the tranny. So I put everything back together, poured in another 5 liters of fluid and... still no OD. So gentlemen: educated guesses, wild guesses, hunches, whatever, please.

 

[BrooklynBay]

Did you check the VSS, and the TPS?

 

[Hande]

I haven't checked either one particulary (wouldn't know what to look for), but aren't those sensors connected to the computer which in turn energizes the 3-4 shift solenoid if all parameters are apropriate. As the computer does
energize the solenoid, it seems these sensors must be working ok.

 

[BrooklynBay]

Have you checked the band, and servo which was mentioned in post # 6?

 

[Hande]

Yes, I put in a new band last week, along with other parts, and the servo
I changed last fall after buying this truck. As I mentioned in an earlier post I did a partial rebuild of the tranny last week; bands, clutches, O-rings, etc.
The bands in the tranny didn't look so bad and the drums weren't glaced. The
only mechanical wear I saw was that the part no: 112 in the ATSG manual's
blow-up picture, "adapter, O/D clutch", was badly worn. It had rotated and the eight tabs on it had worn very thin. As I didn't fancy waiting a week for a two-dollar part from the US, I built the tabs up with weld and then grinded and filed them to fit into the O/D drum. I do not know how important this small and flimsy part is for the OD to work. If it is essential, then this tranny is surely a very bad design. Be how it may, I think that right after putting the tranny back together again, this fix of mine should have worked for a little while anyway. Is the wear of this part a common problem?

 

[Hande]

And yes, another thing. Having driven the truck for a while after the rebuild, with no OD, I decided to check the band adjustments. I backed out the adjuster bolts and tightened them to the specified torque. Only I forgot to take back the OD band adjustment bolt the required two turns. I got into the truck and tried to reverse out of the garage. Nope, no go. The only gear the truck moved in was OD, that is when the shift selector was in the OD position. I didn't drive the truck, just went through the gears to see why I couldn't reverse. I thought I had forgotten to fasten the kick-down linkage, but going under the truck I noticed I hadn't backed out the OD band adjustment. So judging from this the OD would work if the band would tighten around the drum adequately. So why doesn't it tighten? The solenoid gets energized, the hydraulic pressure is within specs. But is there any pressure inside the servo?
Maybe I will have to drill and tap the servo cap for the pressure cauge to see if the servo is in fact pressurized when the solenoid is energized.