My take (I'll send you a bill
): First, find out why your O/D quit working; diagnostics, guesses, tips, tricks, etc. abound on this forum and others. If you didn't tear down the O/D the oil pump would not have been touched--it's bolted in--except to get its roller out of the way. My best guess is the collar on the gearbox output shaft with the cam that drives the pump is on backwards--I KNOW that can be put on bass-ackwards--how did you get the pump out of the way to reinstall the O/D? But run through the electrical diagnostics first.
Second: I wouldn't try a 'flush,' for a couple of reasons; if there is indeed gunk floating around you're all but guaranteed to plug up a hole or small passage in the O/D, requiring a teardown anyway. ATF would be OK for a flush--some use them in gearboxes and O/Ds as practice--but any solvent wouldn't protect gears for long and could seriously damage rubber components. A BJ8 O/D will have rubber O-rings on the operating pistons and could have been retrofitted with O-rings on the accumulator piston.
Solenoid goes in and out of overdrive. The pressure gauge I installed over the operating valves showed no oil pressure. I R&R the pump today. A friend spun the coupling flange, I saw the the pump spring compressing/uncompressing. I'll assume the pump is on the cam and hopefully that was the issue.
I replaced both o-ring operating pistons. I replaced the accumulator housing/piston with the AHSpares modified O-ring conversion unit. I have a new oil pump body/spring/plunger. I replaced the ball bearing/spring/plunger for the oil pump and operating valve.
To flush or not. I didn't have any debris in my prior oil changes. The overdrive worked fine, had 2nd gear issues. The guy who was rebuilding the tranny said, if OD ain't broke, don't fix it. I replied this is the time to open it up and make sure nothing needs addressing. He comment, you could find it doesn't work after opening and putting back together. It was a battle to get this guy to work on the tranny and it took him 3 months. As my father would say, pick your battles. So, it's working, let it be I figured. Now I find debris from the OD is showing up in the oil?
Being there is gunk floating around, I'd think I should address it and get it out. If I don't it will eventually plug up something. Most likely the pin hole in the operating valve.
I can try and flush the system with multiple 30w non detergent oil changes. New 30w, 10 minutes? Drain, new 30w, 10 minutes. Repeat until clean oil?
Does ATF have a cleaner in it and possibly do a better/quicker flush. Say 10 minutes, drain, repeat with new ATF 10 min, check oil for debris. If clean, drain the AFT, run 30w for 10 minutes to flush out the ATF. Then drain/fill with 30w.
I don't want to do any damage to the gears rubber parts or anything in the OD, so I'm doing my due diligence.
Thoughts?
These 3 photos are of the same drain, same amount of oil in the bucket. Thought on the debris?