Fully-Flushing an Automatic Trans'

[88_pacifica]

So, what is the general concensus on this? Obviously it depends on the maintenance of a trans over it's life, but in general is this a good idea? If it has never been serviced, obviously it is bad as you loose the last remaining bits of "frictional ability" the trans has, but lets say the trans fluid is somewhat regularly changed(filter/fluid) and the trans is shifting/operating fine..

Obviously, we all know we should change the filter and fluid together, but, since you cannot fully drain the trans with a filter r&r, about 2/3's fluid is still in the trans, what now? Wouldn't a flush be a good idea to get it all provided the trans is in good shape and maintained? Then, you could change the filter, but you'd immediately lose 1/3 of what you just put in. So, what now? I mean the shops all say flush FTW but we know it is because it is easy/lazy. Is it really beneficial? How do we trust the filter isn't clogged/clogging?

Now, tell me, what you think. I'm not necessarily looking for exact science here as I am knowledgeable enough to know what is right/wrong, but rather opinions. Let me know...

[2.216VTurbo]

My Bro who worked for years on luxury coaches (giant behemoth motorhomes, he'd pick me up for 'test drives':eyebrows:) taught me his full flush method years ago and it works great.

Do your filter, drain the pan etc, reinstall and then fill up about 2 quarts past what you took out of the pan filter drain. Then take the line loose at the trans cooler and attach it to a length of clear PVC hose and run that into a bucket. Start the car and let the pump push the old fluid out of the torque convertor etc, careful, no too much just those 2 quarts you overfilled. Shut er down and add 2 more quarts. Lather, rinse, repeat until the fluid changes color in the clear PVC tube. Now you have a completely flushed system, rehook the line and check the level:thumb: Oh and he has always believed in at least 1/3 volume of the purple "Trick Shift" fluid. I've never had an auto TM so I've only done the flushes in the Wifeys cars, couple BMW's kids mover Yukon's/Tahoe's so I don't really know how compatable the Trick Shift would be inside a 413.

[88_pacifica]

My Bro who worked for years on luxury coaches (giant behemoth motorhomes, he'd pick me up for 'test drives':eyebrows:) taught me his full flush method years ago and it works great.

Do your filter, drain the pan etc, reinstall and then fill up about 2 quarts past what you took out of the pan filter drain. Then take the line loose at the trans cooler and attach it to a length of clear PVC hose and run that into a bucket. Start the car and let the pump push the old fluid out of the torque convertor etc, careful, no too much just those 2 quarts you overfilled. Shut er down and add 2 more quarts. Lather, rinse, repeat until the fluid changes color in the clear PVC tube. Now you have a completely flushed system, rehook the line and check the level:thumb: Oh and he has always believed in at least 1/3 volume of the purple "Trick Shift" fluid. I've never had an auto TM so I've only done the flushes in the Wifeys cars, couple BMW's kids mover Yukon's/Tahoe's so I don't really know how compatable the Trick Shift would be inside a 413.

Thanks Alan, I was wondering if anybody else would come up with that idea. I had the same thought, but I wasn't sure if it would really work. I guess that's what I'll do then.

Oh, and it's for the wifey's car too but I didn't want to reveal that part till I got a good answer. She has a Hyundai Sonata and it's time to replace that "expensive-as-sh1t," unique SP2, $7-a-quart fluid of which there's 15 qts in a full flush. $105 for just the fluid itself since it's "specific" to the foreign cars. :eek: :banghead:

I wondered if that flush method would really work and I guess it will. Good to note for sure...

[Vigo]

with these transmissions if you just let it drain overnight you are getting almost everything out.. granted there is still come fluid in the converter but imo if you let it drain a good while and do that kind of fluid change fairly regularly there is no need for a 'flush' per se.

with the way fluid prices are getting.. well let me put it this way i have a car and an engine/tranny right next to it waiting to be lifted in but i know there's no point since i wont spend the money on oil/coolant/atf on it if i put it together anyway! lol.

[turbovanman²]

Yes, you can do the old oil cooler hose or just change the filter yourself, top it up and drive to your nearest lube or tranny place your trust and have them flush it. I don't mess with that crap anymore, its too messy when they can do it in 20 mins or less with the machines they have, :nod:

Its better if you have 2 people if you do it yourself, one to be by the ig switch and you pouring the fluid in so it doesn't run dry.