Thorough fluid change in auto tranny

eradics · Post by **eradics** » 12 Oct 2006, 14:05

I was wondering what the best method to do a good good job in flushing the auto tranny? fill empty fill empty.. or perhaps take off line from radiator and empty the dirty oil and fill in new in the spout.. any input would be great...

Thanks
Ed R

Kmaniac in California USA · Post by **Kmaniac in California USA** » 12 Oct 2006, 19:11

When I did mine a couple months ago, I did a drain, fill, drive, drain, fill. Very easy to do when you have a drain plug in the tranny pan. Did I end up with absolutely clean fluid? NO! But it was much redder than when I started. Also, the filter in mine is metal mesh unit, not a paper or fiber fill unit. Therefore, I didn't bother to replace. Getting your fluid absolutely clean is a waste since it begins to start collecting spent friction material again when you start to drive.

brucepick · Post by **brucepick** » 12 Oct 2006, 20:51

I've done it three times, changing it via the radiator cooling line. The upper line is the one to use, that's the return line.

I agree on leaving the screen/filter alone. A bit of a pain to get it out, and almost nothing to be gained by it. I hear there's a Volvo service bulletin saying to leave it alone also.

Drain what comes out of pan by removing the center bolt down there, then put the bolt back in and replace the 2 qt. or so.

Then use a gallon jug marked at the 2-qt level. If I recall, a 3/8 inch hose will fit on the radiator nipple. You may or may not need a hose clamp to keep it tight. When removing the existing line, use a second wrench on the fittings large hex so you don't unscrew it out of the radiator. I use a clear pvc hose so I can see the fluid moving through. You want to see it because you don't want to run the tranny dry.

Idle to remove 2 qt. or 2 liters into the marked jug. Then shut down engine and replace the 2 qt. If you try to get out more than 2 qt. you'll see air bubbles in the line - as in, the tranny's circulating pump isn't getting enough fluid. You don't want to do that.

Remove and replace 2 qt. repeatedly till it's nice and clean, and then do another cycle or two. I had to run 14 qt through mine.

I did some calcs that showed you get 91% new fluid after 2 qt x 8, and you get 93 % new after 2 qt x 9 changes. Still easier and cheaper than taking it to a shop.

LaRy · Post by **LaRy** » 13 Oct 2006, 06:06

Brucepick is describing the principle used by Volvo workshops in Sweden. I've done it a couple of times myself. If you use a clear PVC hose, it's very easy to see when you get fresh red oil in return. I used 8 litres of oil.
I (and Volvo) have also been using the upper nipple at the radiator. Just be carefull so you don't destroy the nipple threads at the connection. It's made of aluminum, Volvo technician destroyed it for me, so I had to change the radiator later. When putting back the oil tube hexa nut, start by rotating just with your fingers to find the thread. Finally, use a small torque when using the wrench.

Post by **billofdurham** » 13 Oct 2006, 11:17

To avoid damage to the radiator connection remove the return pipe from the transmission and drain from there.

AW transmission the return pipe is the rearmost one. ZF transmission the return pipe is the lower one.

Bill.

LaRy · Post by **LaRy** » 13 Oct 2006, 11:52

One short comment, if you are lasy it is easier to do it up there (at the radiator). Ohterwise Billofduram, you have absolutely right. I have the origin instruction how it should be done according to Volvo, you should disconnect at the transmission.

Post by **billofdurham** » 15 Oct 2006, 11:49

if you are lasy it is easier to do it up there (at the radiator).

Well, LaRy, normally I am lazy, and always look for the easiest way to do any job but, having seen the damage caused by heavy handed tightening of the pipes at the radiator, I would always work from the transmission. It will take more punishment than the other end.

Bill.