2005 4t45e which is the return line

Ed_Strong · 03-04-2009, 01:40 AM

I would like to do a tranny fluid exchange thru the cooler lines on this tranny. It goes something like this:

1. Disconnect return cooler line, run engine for a few seconds to drain old fluid from pan into a bucket.

2. Remove pan to replace filter, clean pan, magnet and seal.

3. Re-install pan, fill with new Dexron VI fluid and run engine for a few seconds again to drain rest of old fluid from Converter to bucket, repeat as needed to remove all the old fluid from the tranny.

4. Re-install cooler line, top off with fresh fluid and test drive looking for leaks.

Pretty simple procedure that I've used with success on other vehicles before. Only problem is that GM uses a single plate with one single nut to secure both cooler hoses to tranny making it difficult to flush the cooler in the fluid exchange process.

I don't know which is the return line (I'm guessing it's the lower hose) and have not come up with an idea to keep the fluid outlet hose connected to make the fluid flow thru the cooler before it's expelled out the return hose into the waste bucket.

Anybody done this before or that have any ideas I will really appreciate your help.

Ed_Strong · 03-05-2009, 11:35 PM

No body else have done this before that could comment or give me any ideas or suggestions?

denisond3 · 03-06-2009, 09:36 PM

Can you disconnect one fluid hose at the radiator end, or is it combined into s single fitting there as well?
Ive tried flushing auto trannies, but finally settled for draining the pan, refilling and running the engine/shifting gears, etc. Then drained the pan again & refilling it. This gets rid of about 3/4ths of the old - which seems to be adequate. Once, with a 727 tranny whose oil was as black as ink, I just ran the engine with the tranny pan -off-, and had a large catch pan under it. I let it run for maybe 5 minutes, when I saw the amount of oil spraying out drop off noticieably. Then I replaced the pan, refilled it, ran the engine, and of course had to add several more quarts before it stabilized on the tranny dipstick. The fluid on the dipstick was a nice deep Dexron Pink.

Ed_Strong · 03-06-2009, 10:16 PM

Yeah I've tried looking for a way to do it at the radiator, but then the radiator cooler won't get flushed with the tranny. And the other problem is that the lines to the radiator are all metal, run from the passenger side of the radiator then down and towards the tranny making them impossible to maneuver into a waste bucket.

I wish I could get some images on how the cooler lines look when disconnected at the tranny, that would be a big help.
Thanks for taking the time to help, I appreciate that!

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