ATF flush question

[EngineeringBloke]

There's a loop with the transmission, the ATF cooler radiator and the ATF sump at the bottom of the ATF.

Drain and Fill

If you drain and fill, then ATF leaves the system via the drain at the transmission sump. AT is not running at the time, so as the ATF pump is not circulating the ATF, then you may not get all of the old ATF out of the far parts of the AT (e.g. from the torque converter, for example).

Drain via the AFT cooling radiator hose kit

If you use the kit, ATF leaves the system via the ATF cooler radiator line. AT is running, so as the AT ATF pump is running, then you will have circulation through the AT and are likely to get old ATF out of it. However, if you did not do a drain and fill first, you are likely to have older ATF in the sump which will mix with the new ATF.

Note. You can run the AT until AFT stops coming out and then top up, but most people collect the old fluid in a large clear bottle (e.g. a clear 1 gallon water jug) marked in 2 quart quantities. Once the marked level is reached, stop the engine, pour out the old fluid into a very large container for recycling, or just use a lot of jugs. Add an equal amount of new ATF to replace that drained in this stage, and repeat until satisfied.

As I was unclear which direction the ATF was flowing through the AFT cooling line, I put one end of my drain line in the radiator and the other in the ATF cooling hose. I started the engine and saw the ATF entering my clear drain line from one end. I turned off the engine and pulled the dry end of my hose out and put that end into my marked collection bottle.

ATF fill - Adding the ATF after a drain, or the kit pumping

Note. It is critical to not undo bolts on top of the transmission. There is no fill point covered by a bolt. There is one bolt that holds a ring for third gear that once removed allows the ring to move out of position. It is very, very challenging to fix this.

Fill via the ATF dipstick hole with a long thin funnel that is securely placed in the hole. Check this to avoid leaks

The mixing of old and new AFT is not usually considered a problem and the more new AFT you add, the more likely you reduce the amount of old AFT down to almost zero while increasing the new ATF with refreshed ATF qualities and properties.

I saw a European Youtube video where there was a drain and fill and then repeated use of the ATF cooler line kit. The guy collected each 2 liters (about 2 quarts) ATF into separate, clear, large 2 liter bottles. By the 15 or 16 bottle, the ATF coming out of the system was fairly close to the red of the new ATF. I don't think the AT was shifted through the gears during the process.

I was surprised that it had taken so much new ATF to clear out the old fluid. I think that the process of drain and fill replaces about half the fluid. The often suggested approach is to drain and fill, then drive for a while to mix the old and new ATF, ensuring you have gone through all the gears. This drain and fill, and drive can be done several times in a row with progressively more new fluid and less older fluid.

There is no reason not to do something similar with the cooling line exchange. I just suspect that without a drain and fill first, that the sump may not evenly mix the old and new fluid.

ATF temperature
AFT will expand more as it warms. It is important to check the AFT level and ensure you have correctly added the right amount of fluid. It will take a little while, maybe as much as 30 minutes for the AT to reach full operating temperature. Mind the hot engine and hoses while pulling the AFT dipstick. Also use a lint-free cloth to wipe the dipstick to avoid damaging your AT!

If its low, add more (the new ATF does not have to be hot), but if its too high you will have to remove some AFT. There are thin hoses you can insert in the ATF dipstick hole and pull out (siphon out).

Recheck the level again.

[leapdragon]

I recently acquired an '07 XC70 to replace my '02.

The tranny on the '02 had been maintained with regular transmission fluid services and when I bought it at ~100k fluid was pink. I kept up replacements every 25k miles but nonetheless by 170k it was feeling iffy, even with B4 servo upgrade and retrainings.

The '07 had never been changed and was at 180k (yup, I bought a 180k car). It was pitch black and smelled terrible. But shifted smoothly nonetheless. I installed an inline filter, did a 15L flush w/Idemitsu TLS, ran it for 1k miles, and did another 15L flush w/Idemitsu TLS and replaced the inline filter.

Nothing bad happened, transmission shifts the same as it did when I bought it, i.e. far better than the '02 ever did, and now the fluid is nice and pink and fresh.

That's not to say that you won't have trouble, but to say that it's not necessarily a bad thing in all cases, and there was no way that I *wasn't* going to do it.

[Mr. Detail]

Super Herman, sorry for waiting so long to repsond to my post from last month. So are you saying I don't need to use that kit I bought with the clear plastic hose and attachment stuff? Just loosen the drain plug, drain out so much and replace?
I should measure as I drain, yes? I do have that skinny funnel made just for the ATF tube.

[Mr. Detail]

Also a follow up after reading above "leapdragon's" post about installing an "in-line" filter. Is that easy to do (cut the metal tubing) or is there a spot where it can be installed more conveniently?
Leapdragon, what brand inline filter did you purchase?

[MoVolvos]

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Most people use a Magnefine or another brand of Magnetic Oil Filter. Do not cut any metal tubing. Example of installations. Be sure the inner diameter of the filter is the same as the inner diameter of the transhose. A little clear silicone grease will help to insert the filter while slightly enlarging the hose also.




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[MoVolvos]

Also a follow up after reading above "leapdragon's" post about installing an "in-line" filter. Is that easy to do (cut the metal tubing) or is there a spot where it can be installed more conveniently?
Leapdragon, what brand inline filter did you purchase?

Just in case you need hoses there are transmission specific hoses besides the fuel and coolant hose.

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