Maximizing ATF Extraction via Topsider
 

Between filter changes, I remove and replace ATF using a topsider. By doing this several times, I wind up with about 80% new fluid. When I do this with transmission at operating temp on level ground, I get out about 2.3 quarts.

If the car were pointing downward, would I get slightly more? I just don't have a sense as to where the dipstick tube hits with respect to the fluid. Car is a 91 300D.

In this picture, the dipstick tube is the black tube descending from the forward passenger side ending at the bracket. As such I'd raise the front driver side of the car to maximize extraction.

http://www.w124performance.com/image...valvebody1.jpg

The problem is knowing where the extractor tip is in the sump. If you push in too much hose it might curl around the aft end and head for a higher section of the sump. Maybe someone can tell you where the dipstick ends in the tube for reference. Or withdraw the extractor slowly when you hear the gurgling sound.

BTW, I do the same with power steering fluid.

Sixto
87 300D

Front, right corner. Elevating the left side of the car would be your best bet.

so... you don't wanna drain the TC?

Probably doesn't want to pull the belly pans.

Sixto
87 300D

Yep that must hold quite a bit - what is it about 2 litres?

There's a philosophical question of whether the fluid is 80% clean or 20% dirty. As a counterpoint, would you rather have 4 tires with 75% treadlife remaining, or 3 new tires and one down to the cords? Does anyone know how new ATF mixes with old ATF? It's disconcerting enough that a by-the-book ATF replacement replaces only about 90% of the fluid. Besides, the TC drain is right there when you get around to changing the filter.

Sixto
87 300D

Indeed - if you ever take the whole transmission to bits I'm sure like me you'll be amazed at how much of the sodding stuff still bleeds out all over your work surface, the garage floor, the bags, the boxes, your clothing, your shoes...

Of course, I can get the fluild to any degree of purity I want based on the number of extractions.

Do you really find it disconcerting to have 90% pure fluid? Do you feel the same about your oil?

There are things in life that bother me more :)

I'm not questioning your method because I think it's wrong, I just don't understand the benefit. I think the key is determining the transition point between improving old ATF by adding new and pouring good ATF into bad. If you don't extend the filter interval, it seems overly cautions, not that that's a bad thing. If you extend the filter interval, how do you figure how long to go?

I'm spoiled by the TC drain. Our Mopar or Bowtie don't have a drain so I do the bit of flushing through the tranny cooler with the engine running after replacing the filter.

Sixto
87 300D

I think the thing that is a bit misleading is...

...the filter in the transmission.

It isn't like the filter in your engine - OK on the side of the engine. Oil in a transmission doesn't get pumped from the sump through the filter and then into the moving parts. The filter in the transmission is only there to protect the valve body. There isn't much flow through a filter fitted under the valve body.

I think the best way of getting junk out of the transmission is to change the oil and the filter - the best thing about changing the filter is that you have to remove the sump pan and then you have the opportunity to remove all of those glittery bits of junk (that hopefully won't be there)...

In part due to the mess/hassle, and in part due to various threads I've read from people having difficulty changing the filter and gasket (torquing problems, leaking, etc.) as well as dealing with the torque converter, I've never done it myself...my indie does it. But I suppose I could be persuaded to take the plunge. :) For now, the routine that I've settled on is to change the fluid using multiple extractions every 25,000 miles, then every third time (i.e. once every 75,000 miles) have the filter and gasket changed. While this certainly isn't by the book, it saves me a little money (and/or effort). I don't considered a breach in the filter to be likely and, if the filter were starting to get clogged, I figure I'd probably notice it.

I freely admit that I may be being penny wise and pound foolish....

This comment helps confirm me in my unorthodox practice.

BTW next time I DO get the filter changed, I'm going to rip it open to see what it looks like.

My feeling is that if you want to be cheap and not change the filter - well it is your car - your choice. However I think you are missing the point a bit about the process of changing the filter.

The process of draining through the lowest point - carrying heavier crud with it is important. Sucking oil out of the top of the transmission might leave heavier elements in the transmission. Not wiping out the lowest point in the transmission might also leave crud behind.

As I said the filter only protects the valve body. Have you seen the price of replacement brake bands for a 722.3?

Please don't misunderstand me - I'm not preaching - I'm just playing the FSM's advocate!

I'm glad to be educated by you guys....and I enjoy the dialogue. And I'm the very last person in the world who wants unnecessarily to pay for a transmission repair!

When I insert the topsider tube, it goes to the bottom of something. Is it the pan I'm hitting or something else? Also, I had assumed that the crud sticks to the pan until it is cleaned. Is that not correct? Maybe to make sure I extract as much dirt as possible I need to do the extraction as soon as I shut off the engine....I usually wait a bit.

As you might suspect, I use the same procedure for changing my oil. Of course, in that case, the topsider gets out as much as you would when using the drain plug. I can't imagine there's ANY advantage to using the drain plug to change the oil.