With the lack of fluid flowing out the cooler line..arent we back to the pump?
Maybe;
in Neutral
Could be a plugged filter, a misaligned manual valve. the main pressure regulator.the relief valve. the TC control regulator. or a faulty cooler, depending on which side was pulled off.
In Park
skip the misaligned manual valve cuz it is dumping anyway. And because of that, all the pressures are way down.
Volume is not pressure. In Park, very little oll is actually entering the TC, and so very little would be coming out, and whatever is coming out, is dumping into the pan anyway
From the pump, the bulk of oil flow goes to the main regulator, then the manual valve,
From the manual valve it gets distributed to all the other circuits, as the valve calls for.
In reverse, the pressure is unregulated; whatever the pump can put out, the whole circuit gets it. In reverse; from the manual valve, the circuit goes to the hi-drum, and simultaneously to the L/R servo. If one of those is defective, it will hemorrhage fluid, and the pressure will drop like a rock off the tower of Piza. Of those two, the L/R servo has been known to pop out of it's cavity. When this happens the pressure plummets and the L/R band no longer works. That circuit should have 230 to 260psi @1600rpm. If it doesn't even come close, then you have to suspect, one of those two. You can fix the L/R servo from dropping the pan.
If you have any pressure in that circuit at all,even with the servo popped out, then the pump is working.
If you have NO pressure in that circuit,then the pump is likely faulty.
As for the hi-drum; if it is faulty, the trans has to come down. But if ONLY the hi-drum is faulty, you should still have all gears except reverse and third.
And if ONLY the L/R servo is not working but not hemorrhaging, you might never know it because the trans will still drive thru the sprag.
There is no way for oil to get out of the TC except thru the cooler. If the cooler was plugged. the TC pressure would rise, but there is no way to check it.
The hi-pressure relief is set to ~275psi. If the reverse circuit is working right, you can rev it up and check your max pressure. If it climbs to about that number, then you know there is nothing wrong with that circuit. The TC control valve
could still be stuck, preventing oil flow into the TC, and that would cause a no-drive situation , and yes, I have seen a few stuck TC control valves. This too can be fixed from the pan.
The point is this; 5 minutes after starting the engine with a pressure gauge on the L/R circuit, you will know if the trans has to come down or not.
If you just take it down with no testing, then your rebuilder has no idea what to look for, except by what answers are given to his questions.
So maybe the trans needs to come down, and maybe not, IDK. But the pressure test would clue me in right quick. At age 67, I'm not interested in pulling an auto down, if I don't have to.
BTW,
once the pan is off, and the VB is down,
then you can air-test all those clutches and servos ....... from the pan, and that will tell you AGAIN, if the trans has to come down ..... or not. Sortof like a second witness, but this test has more authority to it.
In your driveway, taking the trans down is an all-afternoon affair. Putting it back in, is another afternoon. And you need a box of tools and a jack, and probably a helper.
Oil-pressure testing, in your driveway, is an hour or less, unless you might have a physical handicap. And you need one wrench,or two at most, and a helper on the gas-pedal she won't even get dirty.
I know what I would be doing.
