I get the Red bottle Valvoline MaxLife ATF at walmart stuff is very good.

 

Spool valve is part of the valve body. You could remove the valve body and remove the spool valves to check for one that does not move smoothing. Lots of little check ***** in there so you really need the trans manual before you do that. You could replace the solenoids, but kinda doubt that is it. Have you researched the flow circuit on unlock condition? I think your hypothesis hold some water that the the appropriate valve is not working correctly and it is only after rpm drops enough that pressure drops to allow it to disengage.

 

Is the "spool valve(s)" you refer to the MV4 pressure regulating solenoids valve? Or the MV1-MV2 shift solenoids?

In any case, I did another, more careful drive test.

Here are the results.

Drove it up to 35-40 MPH and then let off accelerator and coasted. No apparent coupling of engine and transmission via lockup clutch, i.e., the RPMs immediately dropped from 1,500 to 1,000.

Then took it up to 60 MPH (about 2,100-2,250 RPM), let off accelerator and "coasted". I could clearly feel the drag of the engine as the MPH and RPMs dropped slowly in lockstep until about 35-40 MPH, when the RPMs (engine) and MPH (transmission) decoupled, RPMs dropped to 1,000 and the vehicle rolled freely, i.e., no perceptible engine drag.

One thing I noticed in both the 35 and 60 MPH drive tests was that once the speed dropped to about 30 MPH, the RPMs dropped to 700 RPM -- the idle level. I am guessing that at and below this 30-ish speed, the fluid coupling between the impeller and turbine became fully decoupled and the transmission turned freely.

So what'ya think?

I think I am going to the junkyard this weekend and pull a whole valve block and do a swap out to see what happens (BTW, I did find the red Valvoline Dex3).

BTW2, when I replaced the fluid and trans fliter 30-35K miles ago, I don't recall the pickup tube shown in the picture below.

 

The spool valves are not in that exploded view. The lock up solenoid valve could be the issue, but I am not sure if it is normally open or normally closed. It may be activating a spool valve, again not sure as I have not researched it. An entire valve body swap may fix it, if not, it likely internal.

 

OK, I finally replaced the lock up solenoid on the valve body and the lockup issue appears to be fixed: the lockup clutch now appears to be releasing at speed when I let off the accelerator (based on immediate RPM drop and minimal engine "braking"), and not only when the speed drops to 33-34mph).

However, now I have the infamous blinking S+M+D+P0722 issue that I have started to read about. Car will launch normally in Drive, then appears to be stuck in 1st gear 'til about 30 or so, when it hard shifts up to 4th gear then stays there. The green S and M idiot lights blink and the CEL show a P0722 code. It is drivable but not great launch from a stop light in 4th gear. When I turn the beast off and then on again, it re-sets, but then exhibits the same behavior.

My first thought was that I somehow didn't get the output shaft speed sensor seated right with the spring steel clip that holds the sensor in-place.

Could I have actually screwed that up or am I having a coincidental low bus voltage issue issue?

Thanks all for the help. I am going to start a new thread referencing this one to see if anyone has a comprehensive diagnostic approach and solution to the Blinking S+M+D+P0722 issue.

 

You could probably benefit from a scanner that can read and diagnose transmission codes. There are several that will do it, I have not used my nanocom with the transmission yet but both my Delphi and my iCarsoft 930 can diagnose transmission issues.

 

I'll look into a scanner.

In the meantime, I went back out to the donor I've been cannibalizing to get a solenoid wiring harness and output shaft speed sensor, and I think I found my problem

When I replaced the lock up solenoid, I didn't disconnect the solenoid harness from the transmission body, Instead, we dropped the valve block just enough to get in there to replace the lockup solenoid.

When we were putting the valve block back up and fitting it to the transmission body itself, there’s a lever on the body that is supposed to connect to a plunger on the valve block that goes to the manual solenoid, and I think we might’ve not reconnected the lever to the plunger. It might well be the reason that we were not able to get that thing to line up easily and we struggled with aligning itit.

Here are the pics about the lever in the body and the plunger on the valve block that I got when I was out early this morning at junk yard getting the speed sensor and the transmission wiring harness out of the one remaining Land rover disco out there right now.

There is no reference to either that plunger into the manual solenoid body or the mechanical lever dropping down from transmission body, but if the plunger went in a bit, I think the plunger and lever could have stayed disconnected after the valve block was bolted back in.

What'ya think?

 

Yeah, absolutely. Sounds like you also need a transmission manual. Email me and I will send you a transmission manual.

 

Popped the tranny sump last weekend, and yes, the lever was seated behind the plunger rather than in the plunger receiver.

Aligned the shift lever and plunger, buttoned 'er up and filled 'er up, no more lockup clutch issue (as best I can tell, but instead now the drivetrain has something of a small but perceptible rough rumble when accelerating, disappearing at constant speed. Almost feels like a bad tire, but goes away when at speed or coasting. Also not a driveshaft as I checked those (as well as the transfer case fluid level).

Almost seems like either not enough fluid or that the fluid is foaming so the TC is not fully hydraulically engaging, however, fluid level has been checked and a little fluid runs out when the filler plug is removed.

So there is no loss of fluid, nor any in the bell housing after inspecting it via the inspection port at the bottom.

Kind of in whack-a-mole mode now. Thoughts? Can a TC fail in ways other than leaking, e.g., with the stator that provides the torque multiplication during launch/acceleration? Can a TC fail catastrophically or is it more graceful?

 

Yes, torque converter can fail besides just clutches, although unusual. DonRW007 had a torque converter failure recently. Of course the problem with TC failure is it sends bits of metal throughout the transmission. I would start looking for a replacement if I were you.