1998 4X4, 3.4L Transmission Drain and Fill. To do, or not to do.

[t4r2lx570]

I've religiously changed the oil in this vehicle every 3k to 5k. Diffs and Xfer case fluids have been changed too.

The transmission? Unknown history.

At this point there are 350K miles on this vehicle on the original transmission. Should I throw caution to the wind, or should I start some small drain and fill procedures on this tranny to give it longer life? I'd hate to break it now when nothing seems to be wrong, but it also seems wrong to not at least try to get some new fluid in there.

Thoughts?

 

[SteveH]

Assuming an automatic trans? I would drain and fill the pan, then pull the cooler line (under the front bumper), start the truck and run it until 2 qts. come out (have an assistant and a milk jug) and then shut off the engine, add 2 quarts, repeat, and so on, until the fluid coming out looks clean. It took 4 gallons of Valvoline Dex III from Walmart to do this on mine.

The trans fluid (before) looked like coffee, so it was time. Mine had 242K and the PO had simply done a drain/refill once, but never the full pump-out gig.

 

[t4r2lx570]

Assuming an automatic trans? I would drain and fill the pan, then pull the cooler line (under the front bumper), start the truck and run it until 2 qts. come out (have an assistant and a milk jug) and then shut off the engine, add 2 quarts, repeat, and so on, until the fluid coming out looks clean. It took 4 gallons of Valvoline Dex III from Walmart to do this on mine.

The trans fluid (before) looked like coffee, so it was time. Mine had 242K and the PO had simply done a drain/refill once, but never the full pump-out gig.

Thank you Steve. I will pursue this course of action.

 

[aowRS]

I've owned my '01 4Runner since new (498,000 miles now) and had the tranny fluid fully exchanged at every 100k interval using a BG machine. The truck still shifts like it did 20 years ago.
At around 450,000 miles, I was curious about the condition of the transmission filter/screen. So I purchased a new one from Toyota, along with a tube of FIPG. Other than the pan having a small amount of sludge at the bottom, the original filter was surprisingly clean.
In the next month or so I'll do my own fluid exchange using the method described above. Already have 16qts of Toyota-branded fluid waiting in the garage.


Andreas

 

[NMuzj100]

Assuming an automatic trans? I would drain and fill the pan, then pull the cooler line (under the front bumper), start the truck and run it until 2 qts. come out (have an assistant and a milk jug) and then shut off the engine, add 2 quarts, repeat, and so on, until the fluid coming out looks clean. It took 4 gallons of Valvoline Dex III from Walmart to do this on mine.

This is the way I would go and exactly how I have done my Land Cruiser and Camry with great results. (Only took about 10 quarts of fluid in LC)

What fluid are you going to use?

 

[ozarkmud]

Yours has a dipstick, right? I seemed to recall that my '98 did. I don't think these are sealed units, but I also am not 100% sure what the fill procedure is.