How to Drain/Refill Automatic Transmission

I do one a year and that’s just my method. That way the fluid is always being refreshed. Many ways to accomplish the same thing I suppose.

 

I haven’t found a way yet to get all the fluid out of each bottle, so I never know exactly how much I’m putting in. I pour the dregs all into the last one but it’s still got a decent amount left in the bottom at the end...

 

first off, each bottle doesn’t hold exactly the same. My method is I use a gal clear milk jug. Drain into milk jug. Mark level with sharpie. Dump out milk jug and refill to mark with new fluid. Dump back in pan with tube and funnel through engine bay. 3 qts. I actually counted the ounces a few times ago just out of curiosity.

The very last thing you do is remove funnel and blow in tube to push the last bit of fluid into pan.

 

I wonder if there’s any functional difference between filling from the plug on the case and filling from the engine bay. Makes one question why there’s a fill plug on the case at all, unless there’s a specific reason to fill from there.

 

It’s the same plug, just a different way to fill with gravity to do the work. I have used the bottle pump method and the gallon pump sprayer method before. The tube and funnel is the best.

 

A little extra added to drain off during temp check.

 

Are you going to do 4 D&Fs in one sitting?

If so, all you will end up doing is replacing the fluid you just replaced.

You need to drive the truck between D&Fs. I don't mean around the block, either. You need to let the new fluid circulate through the transmission - it will act as a cleaner and pick up particulates from inside the trans. Also, it will mix with the old fluid.

This way, next D&F, you get some particulates and more old fluid out.

 

Aren't both ways technically reading the temp from the same source?

Yep, that was my thought as well.

I hate math.....

I planned on first checking the overflow plug to confirm it was at the proper level. Then drain and drop the pan. Clean pan, magnets, etc then reinstall with a new gasket. Refill exactly what was drained and drive it for a day or two. Then do another drain and fill x 3 over the next few days. I planned on doing it over a week or so, that way I'd be driving it in between.

 

The volume drained out is not really relevant.

You want the transmission filled to the proper/correct level. Just before you drain it, it may/probably will be low of fluid. Not counting what you spill.

I think a lot of you are putting too much emphasis on the part that doesn't really matter.

How many of you check the amount of oil you drain out of the engine each time? Yes, I realize the engine blows out oil over time - but the transmission can seep fluid as well.

 

FWIW. When I did the drain/filter on my A/T. After several Temp Check runs, the tranny was running about 3 quarts low. I drained a little over 3 qts, added 6.5 quarts, level check released about 1/2 quart.

Anyhow, the point....Don't trust the tranny is filled to the proper level. You never know from previous Wrenchers the condition of the system.

Prior to me doing the work the shifts were noticeable to hard. Now, the shifts are so smooth I need to watch the Tach to notice the shifts.

 

3 quarts low.
looks like I’ll be doing the temp check this weekend!!

 

Here is something to think about.

All components (engine, tranny, xfer case, diff) have a specified fill quantity. It doesn't matter how much you drain. What matters is how much is in the component.

For instance, we all know the 1GR-FE needs about 6.2 quarts to fill during an oil/filter change. Say you pull the drain plug, only 2 quarts come out that you accurately measured. You add the 2 quarts. Perfect? Not, its still at least 4 quarts short.

The tranny is no different. Don't pay attention to how much is drained....it don't matter. What matters is the proper fill level. Run the Temp Check procedure to verify the proper fill level.

 

Here is a video for folks to help put their rigs into "Temp check" mode...

https://www.youtube.com/watch?v=qvcgIxW9VqA

 

True I don’t do it with engine oil or diffs etc.
My last truck was manual so you fill til it comes out the fill hole.
I do check to see how much engine oil it gives back at oil changes and even cut open filters.
I will do the temp check this weekend just was lazy didn’t think the tranny would use or burn up fluid.
I will report my findings!’

 

Unlike the differentials, transfer case and engine, you don’t drain the trans completely empty and then fill it up with the proper amount. You have to drain it while filling it. It very much matters how much you drain out so you can be in the ballpark as to how much you need to add back in. Obviously as a final step you can confirm the amount with the temp check mode procedure.

 

So I just did the temp check!
Pulled the hex and got nothing!
I shut it down put in qt and ran thru the gears a few times.
Put it back in temp check drained a little over half a qt back so we were pretty close!

 

This seems challenging if you're dropping the pan.