Torque Converter Question

Hello all. My 2012 4WD double cab is due for transmission fluid flush and replace. (60K per Toyota) Jiffy Lube, to their credit freely admitted to being unable to access the fluid contained in the torque converter due to this requiring (sounds like) a proprietary tool. SO...before I get crucified by the dealer, I thought I should ask those more experienced than I. What do you recommend here? Thank you.

 

Lots of opinions on here. Me, I'm a fan of just draining the pan and replacing what was drained.

No one can access the TC unless you do a complete pump out and replacement of all the fluid.

Much quicker to do a drain and fill then do another in 3 or so months. Almost all the fluid will be fresh. Much cheaper and easier as well.

 

Most people just do a drain and fill a few times and get most of it out that way.

You might get more responses if you post this question in the second gen forum.. the one near the top of the list

 

That method makes sense to me too. What fraction of the total volume of fluid is inaccessible in the TC? I was guessing about 1/3...? Thanks

 

You know...I thought I did that. Thanks.

 

That's always been my rule of thumb.

 

There is about 11 quarts of fluid in the transmission, cooler, lines etc. A drain and fill will replace 3-4 quarts.

 

Some torque converters have drain plug !!!!

You can also drill and tap the converter for pipe plug

 

I like it. Too advanced for me at the moment but that's something I would do.

 

If I read you right, that means that simply draining it without addressing the torque converter would leave about 2/3 of the dirty fluid in there. True statement?

 

True

, This is why you do another drain and fill at a later time. This will ensure that "most" of the fluid has been exchanged.

 

Correct. Drain and fill is classic diminishing returns.

 

What does your response mean? What is "diminishing"?

 

Assume DYI drain and fill has a fixed cost. ~$18 Valvoline MaxLife + $5 crush washers = $23 total costs

In the first drain and fill you replace 3/11 (3 quarts out of 11 quarts) of the original trans fluid in the trans system.
In the second drain and fill you replace about 2 quarts of original fluid and 1 quart of “new” fluid.
By the third drain and fill, you are replacing about 1.5 quarts original fluid and 1.5 quarts “new” fluid.
By the fourth drain and fill, you are replacing more new fluid than original fluid.

The costs remain static. The additional positive hoped for effect, removing the original fluid, diminishes with each iteration. Diminishing returns.

 

And a badly inefficient instance of it at that. If we round and say there are 12 quarts in there and, you can only replace 4 in any one drain, the resultant mixture is 66% old dirty fluid. Recomputing that ratio based on successive procedures in which only 4 quarts are replaced, you would have to do it 5 times to get below 20% dirty. (This would go to infinity and you'd still never get all the old crap out of there...) The next challenge would be to write out the formula which captures that rate of change clean/dirty.

So maybe you do that dance twice and then repeat once a year so in a few years you're maintaining pretty much new fluid in there...Am I getting close?

 

You got it.

At this point in my trucks evolution, generally once a year: I pull off the transmission skid, beat dents flatter, hit the rust with POR15 or Fluid Film, grease the drive shaft, do a transmission drain and fill, take it in for a front end alignment, tire balance & rotation ....

 

OK copy all. Thanks. BTW I see you're from MD. I graduated 84' in Bethesda myself. Take care

 

Update after the fact. My determination was ultimately: $250 at the dealership is the right answer; the Toyota-prescribed procedure is to completely drain & replace via the fluid lines - same thing Jiffy Lube does at about the same price, surprisingly. Apparently there are factory-proprietary attachments on the lines in order to make the transmission resistant to anything apart from a Toyota service center.