tranny fluid change with Mityvac

[matrass]

Thinking of doing a transmission fluid change with my Mityvac . question is how much fluid would I remove through the dipstick ? was planning on getting out what I could though the dipstick, then disconnecting the line to the oil cooler and flushing out the old stuff in a 5 gallon bucket. once the color changes to the newer looking fluid I am done. would this get most of the old fluid out ?

 

[PT1]

Find the capacity of the trans and add 2 quarts. I do multiple drain fills with the vac ( and drive a day in between)until I get to 90% new fluid and call it good. No lines to disconnect and no drain plugs to deal with. I have been doing this for years successfully. There is a drain/fill spreadsheet on here that will calculate how many fills you need per trans capacity and how much you extract each time. You won't know how much fluid you can get out until you try it. I had a Lexus RX330 that held 11qts and I could get 5 qts out with the extractor.

 

[Kestas]

I'm thinking you don't even have to bother with the Mityvac. Disconnecting the cooler line and running the engine (as you plan to do) should empty the pan as a start.

I would still urge you to drop the pan to change the filter and clean the pan if it hasn't been done for a while before doing the fluid exchange.

Otherwise your plan is sound.

 

[Donald]

You will have the least mixing of ATF if you can somehow change the ATF in the pan before a cooler line flush. What PT1 mentions will certainly work, but wastes a lot of ATF for no good reason, even worse if its expensive synthetic ATF.

I am assuming your vehicle does not have a drain plug, thus its reasonable to drain the pan via dipstick before you start the cooler line flush.

As for the transmission filter, if your old ATF looks somewhat decent you should be OK, if it looks dark and smells burnt then maybe you do need to drop the pan, change the filter and wipe the pan clean.

 

[matrass]

Thanks for the ideas so far guys. the filter should be descent as it was changed around 10,000 miles ago and the Jimmy never sees and towing. thinking that I could use the mity vac to drain the pan, then do the transmission cooler line flush. I would be looking for the line that is warmer ( meaning outlet line ) to disconnect and run into the bucket , correct ? now the choice of transmission fluid. it is a GM suv. went to the Amsoil site and it states total capacity is 11 quarts. want to get this done as I will be hading the truck off to my son in the late Spring and I want a little peace of mind.

 

[Donald]

You want the cooler line of the two lines and disconnect it at the cooler and install 3-4' of clear plastic hose going to a bucket where you can see how much has come out. One gal WW fluid containers work fine. That should be the return and its best to use that line so you flush out the cooler also. Its easier than it sounds and can certainly be done by one person even the first time.

Throw in a Magnefine while you have the line disconnected. Will take an extra 5 minutes and $20.