How to Drain/Refill Automatic Transmission

I've been reading this thread for several years......... What happens to the trans when overfull? Not talking about a gross mistake - maybe a quart over? I'm thinking that too much will pressurize the case at some elevated temp and then cause a sealing issue.

What to do if your truck (like mine) is sitting in the driveway, not operated in couple of days - and it is now fully heat soaked to ambient - 110ºF yesterday afternoon. Best I can figure.... start it, run trans to drive and reverse to fill trans (how many seconds?). Then check level, add sacrifice fluid if necessary to top it up correctly, follow by stop, measure drainage and re-fill.

MY IR temp gun matches the fancy RayTek at work so I'm pretty sure it would catch the trans pan temp pretty quick. But it will hit 115º in a big hurry I'm sure.

 

Simple, This isn’t the time of yr. to do it for you.

 

A bit over should hurt anything, you can't check it in the morning before it gets that hot out?

As far as running it through the ranges just hit each one for a couple seconds then go the opposite way through each one for a couple seconds then back to park.

 

It was 91º at about 1:30 AM last nite - too much pavement around here!

Mostly interested in how much over "full" is too much. This is such a flaky way of checking it must have some serious amount of tolerence.

 

They don't give us that information but I wouldn't want to be more than a quart over.

I'd check it first thing in the morning, you should be in the temp range then.

 

Agree with @Dm93 above. Do it in the morning and you'll be fine. It won't warm up that quick.

I just did mine a few weeks ago - lows 90s in the garage. Get all your tools ready, your drain pan, new crush washer, scan tool, etc and go for it. 3-4 seconds in each gear all the way down to L and all the way back to P. Then watch the temp and get under there as soon as its in range.

For what its worth, it would be slightly underfilled if you were over temp.

 

I had planned to do mine a few weeks ago but am just going to wait until October now. As others have said, you should be able to do the temp check when it's blazingly hot outside but your window of opportunity is really small.

For me, there's a step in there that will add to the time and heat:

1. Drain pan, refill +overfill by 1qt
2. Turn on engine, cycle shifter through each position to get fresh ATF into the various valve body passages <<<This step
3. Turn off engine, do OBD jumper
4. Use shifter motions to get into temp check mode
5. Wait for AT light and then drain to a trickle.

 

Just FYI you don’t have to shut the engine off in between circulating the fluid and jumping the OBD.

 

Yes, this.

And a few degrees off from optimal is probably not going to result in a significant difference in fluid level.

 

I know when I did mine, I had to wait 3-4hrs for it to cool. And once I seen it was 98° at the pan, I said send it. I done cycled the fluid already. So, all I had to do was start it to check it. It took me about 1-2min to check the fluid and get it all situated. It heated up to 108° in that time. So, you have to be quick about it.

 

@babylon5 only thing that made me question the Scan Gauge II was that it was reading what I thought was the right temp range (115-130F) but the truck in temp check was not - hot wiring the #4 & #13 OBDII sensor. It makes more sense that the temp range for my truck isn't 115-130F but 95-115F... but now that I say that outlaid the truck's AT Temp light should have been blinking as I was over the correct temp range at 128F but you can see in the video I wasn't getting any AT Temp light flashing.

Honestly I'm not going to worry about it why the dash AT Temp light isn't lighting up in temp check mode - I'll just go off the scanguage to confirm temps between 95-115F then check the overflow.

 

Awesome and thorough write up! Love it!

 

Fantastic job ,this Tacoma business nowadays for an 81 year old is a bit mind boggling ! Looked high & low for that tranny dip stick ha ha ! If it wasn't for you young Bucks & Tacoma World I would be up a creek without a paddle ! God Bless ya PS: Just went through a bad experience at a new shop replacing a carrier bearing , that's another story ! I made a copy of another entry in Tacoma World for their mechanic for Carrier bearings ,u-joints , drive lines etc. Who's teaching these guy's ! ? "Never let the old man in " I'm doing good so far !

 

I found using an IR temp gun to be far easier then jumpering the obd connector. It's foolproof and works every time. With the light sometimes I'd get the sequence right and sometimes it didn't want to go into temp check mode. By comparison the IR gun was point and shoot. There's about a 3 degree drop in readings compared to trans temp read from a sensor.

 

Finally got around to do a drain and fill. About 120,000 miles. Decided to see if it was possible to fill from above by the air cleaner. Bought 5/8OD 1/2ID clear vinyl tubing. Used a cork in the lower end of the tubing so no dirt worked it way into the tubing snaking it to the fill hole, removed cork and perfect snug fit into the fill hole, ran the tubing up to just behind the air cleaner. Tied tubing to harness by the fill hole so that the tubing ran above the fill hole. Measured new fluid approx same as what drained out. Poured it into the funnel and no gurgling. Will do this 3 times then set 115 temp and do fluid check overflow.

 

Nice setup.
Note specified check temp was changed in 08 to 95-115F per TSB 0129-08

The OP hasn't been updated to note this.

 

Awesome thanks much, duly noted.

 

Awesome Thread! I had to cycle through the gears fast to get the AT Temp Mode on. I ordered the OEM Filter, O ring, Bolts, and washers for the next round!

 

I can’t imagine it would be different than most other auto trans, it will just puke it out the vent
Not necessarily bad, at least for the transmission; although it can be very bad if that hot fluid drops on to hotter exhaust

 

Thank you for this tip. I have done the ATF drain/fill twice using the shampoo pump method, but for some reason I guess my pump's seals started to deterioriate so it was making a huge mess today while I was trying to do my 3rd drain/fill. I remembered your pic so I rigged up a similar hose and it was absolutely spotless for getting fluid into the trans. No drips or spills anywhere.