727 Rebuild Woes: Oil Pump stator / drum air leak
Simple, install the pistons, return springs, retainer, and snap ring; no clutches....air pressure will push the piston up out of the bottom of the drum, seals pop out, piston goes back down and snags seals...you sure you ever worked on a tranny?
Yes. I have rebuilt one 42RE automatic transmission. Seems to be successful so far.. I guess time will tell.. I am not claiming to be a profession transmission tech, or an expert by any means. I am just trying to assist someone who appears to be trying to learn how to do this operation himself, maybe for the first time, like I was.
I had forgotten that there there is a snap ring that captures the piston/spring assembly and limits the piston travel. I was thinking in my mind that the selective snap-ring and second pressure plate was retaining the whole piston/clutch assembly. I was clearly wrong there. I will own that one absolutely.
I just know my drums didn't leak, and appeared to engage and disengage correctly. So, I was offering what I thought was legitimate information. Please correct me if I am wrong on any account. I don't wan't to make this guys project any harder than it needs to be...
I had installed the loaded direct clutch drum on the pump/stator assembly and applied air. Then, I installed the loaded forward drum on the assembly. Then, I secured the forward drum and applied air to that. (I figured this is what he was doing as well..with fully loaded units..) I retested both for actuation via the case ports after the assemblies were reinstalled into the case.
The fact that he has leaks on the direct, and forward clutch respectively makes me think it could be swapped/improperly installed lip seals... Assuming there is not major seal surface damage, I'm not sure what other area would affect both clutch packs during an air bench test besides stator/pump misalignment or stator/forward drum sealing rings.. Which, appears to be his focus. But, he has tried multiple approaches (swapping seals) there with the same result. Maybe it's possibly the sealing rings on the input shaft/direct hub assembly? But, the later seems like it would likely affect only the forward drum, and not the direct drum as it actuates on the bench without the input shaft in place.. That leads me back to piston lip seals as a very possible cause.
I think a good approach is to help him by suggesting what he should do, as far as checks and assessment. Rather than what to 'never' do. Especially, if it is not obvious he was even attempting the 'no-no' unloaded method.