I would say not possible without running the engine as the torque converter is supplied by the pump in the gearbox and I doubt you can effectively pull oil through this internal pump.

Milltime wrote:

Thanks very much for the recommendations. 20l duly ordered from Smith and Allan. I’m planning to flush from the cooler connections. The only additional thing I’m planning to do is empty the sump and refill with new oil before I flush. My thinking is if I just flush it, I have to dilute all the oil in the sump as well as the oil in the torque converter. If I have already changed the sump oil, my theory is that it will flush with less fluid as the new fluid in the sump should give it a bit of a head start. Time will tell!

jules wrote:

A large amount of ATF (about 3L) is left inside the torque convertor during each draining (about 4 L drains out). So a single drain and refill will only replace 57% of the old ATF. You need to run the gearbox after each drain and fill to mix up the old and new ATF and then repeat the process. 3 cycles replaces 92% and 4 cycles 97%. So you need about 12L of ATF to do 3 cycles.

I can assure you, it takes much more than 3 drain/refills to replace anywhere near 90% of the oil in an autobox

I think Im correct in that the autobox holds 7L of ATF.
Does 3L come out with each drain or 4L ? I thought it was 4L but its a while since Ive done it.

If its 3L then 4L will obviously remain.

Then according to my spreadsheet it was take 4 cycles of 3L drain/fill/run to remove 89% of the old oil and 5 cycles to remove 94% through serial dilution (requiring 15L of new ATF) Jules

jules wrote:

Are you refilling after your initial drain, before flushing? Im not sure if running the gearbox less than half full is a good idea.

jules wrote:

I think Im correct in that the autobox holds 7L of ATF.
Does 3L come out with each drain or 4L ? I thought it was 4L but its a while since Ive done it.

If its 3L then 4L will obviously remain.

Then according to my spreadsheet it was take 4 cycles of 3L drain/fill/run to remove 89% of the old oil and 5 cycles to remove 94% through serial dilution (requiring 15L of new ATF)

Jules

I’ve changed about 15 quarts of ATF in the last 10 years for my Freel2

So I guess I am at 94%

Here is how much I can drain out

Click image to enlarge

Hi p_gill I had to look it up but a US quart is 946ml (UK quart is 1136ml). So yes there is very little of the original ATF left. But some of your "new" ATF could be quite old now depending upon when it was exchanged and your mileage. Jules

About 3.85L comes out with every drain. I've been doing it once per year over the last 10 years. I measure exactly what comes out and replace with the same amount at same temperature.

I don't use the level plug as I believe the plug measures the minimum ATF required for safe operation. If you think about it from the manufacturer's point of view, when/if there's a problem with a transmission box, they would want to know did the box have the minimum fluid required for safe operation? The easiest way for them to do that would be to get the box to operating temperature and open the level plug to see if anything comes out.

If the plug was to measure the maximum fluid level it wouldn't tell the manufacturer anything if no fluid came out. For all they know some fluid could been "used up/ leaked out but the remaining amount could be sufficient. Thus I believe the lower limit is more critical for them to be able to measure.

Since the level plug can only measure a single "point of volume" (it's not a dipstick with a range from low to high) I believe it is measuring the low point. This would explain the discrepancy in reported volume replaced by people who measure how much came out (the first time they did it) vs people who go by the level plug. MY10 TD4 SE Auto

This was the gearbox in my Disco 3

102k miles, previous owner had never had an oil change

Oil capacity is 11 litres

I drained the box, replaced the filter and torque converter, which took 6.5 litres to refill

The gearbox input seal then had a leak, so the gearbox was drained, TC removed, new seal fitted, then a further 5 litres to refill

Then the box was flushed. Old oil on the right, new oil on the left...
I'll let you decide how much of the old oil was still left

jules wrote:

Hi p_gill I had to look it up but a US quart is 946ml (UK quart is 1136ml). So yes there is very little of the original ATF left. But some of your "new" ATF could be quite old now depending upon when it was exchanged and your mileage.

I shouldn't read these threads, lol. I changed my trans fluid on my new to me (150,000 kms, one year+ ago, when I bought it with little dealer service history) twice since ownership, now at 180,000+ kms. Now, I am going to want to do it again as I am likely at less than 60% new fluid . Cheap preventative maintenance though! I did already purchase the fluid, Amsoil multi vehicle synthetic, back in December however!

ATF flush carried out today with a home made system, based on the tips on this post. Without the input from you all on this post, I would never have attempted it. Thanks very much. Some more info on my method:

12v pump off amazon. 1/2” x 5m reinforced pvc tube off eBay. 2 x 10 litre containers calibrated in litres using a plastic measuring jug. Fluid purchased 20 litres from Smith and Allan to JWS 3309.

Old fluid taken out from feed hose in to the cooler, which is definitely the top, not the bottom hose. This joint was tricky. I could have done with some 1/2” Steel tube to make the connection. I used some rubber fuel hose that was the right outer diameter and added some cable ties to stop it blowing off. It actually held with no leaks.

To start with, I dumped the oil in the sump which was about 3.25 litres to get a head start. Then refilled with same amount of fluid using the 12V pump supplying in to the oil cooler. From the cooler, the oil goes straight in to the sump, so I didn’t actually use the filler on the gearbox at all.

Then switched on both the 12 volt pump and switched the engine on and moved through the gears. 12 volt pump did not quite keep up with the gearbox pumping the old fluid out, so engine was switched off briefly about 3 times. The way I had positioned the containers, I could see exactly what was happening all the time. In total I used 15 litres of the ATF fluid I had bought, leaving 5 left over. This included an overfill of 0.5 litres to set the level. At that flush quantity, the colour of fluid being pumped out was almost the same colour as the new fluid. To start with the fluid was almost black but no burning. The flushing system was then disconnected and the cooler hose reconnected.


The gearbox ATF was then heated by running the engine and running through the gears periodically until I measured 60 degrees with a handheld laser thermometer, pointed at the bottom of the steel side panel to the gearbox. The level was then checked with the engine running and the excess fluid drained off. I haven’t had the chance to drive the car yet, but looking forward to seeing how it goes. The fluid change was precautionary, the gearbox was still working pretty well.

The hardest part was connecting to the cooler pipe. The flushing was easy, far easier in fact than extracting the oil from the front transfer box, which was an absolute pig. For the sake of a few pennies, why didn’t they fit drain plugs? Same goes for the rear diff.

Once again many thanks for the postings on this thread. Really helpful.

Thanks for the fantastic post Milltime

I had ordered 20 litres of fluid ready to do a standard 'drop and fill' but decided to look back at this thread for 'tips' before I started mine and found your post. Have ordered a pump (need it for my R53 Mini as well) so will be doing a flush this weekend. I'll try and grab some more pics to add to this thread whilst I'm at it

Mikey wrote:

This was the gearbox in my Disco 3

102k miles, previous owner had never had an oil change

Oil capacity is 11 litres

I drained the box, replaced the filter and torque converter, which took 6.5 litres to refill

The gearbox input seal then had a leak, so the gearbox was drained, TC removed, new seal fitted, then a further 5 litres to refill

Then the box was flushed. Old oil on the right, new oil on the left...
I'll let you decide how much of the old oil was still left

impact wrote:

About 3.85L comes out with every drain. I've been doing it once per year over the last 10 years. I measure exactly what comes out and replace with the same amount at same temperature.

I don't use the level plug as I believe the plug measures the minimum ATF required for safe operation. If you think about it from the manufacturer's point of view, when/if there's a problem with a transmission box, they would want to know did the box have the minimum fluid required for safe operation? The easiest way for them to do that would be to get the box to operating temperature and open the level plug to see if anything comes out.

If the plug was to measure the maximum fluid level it wouldn't tell the manufacturer anything if no fluid came out. For all they know some fluid could been "used up/ leaked out but the remaining amount could be sufficient. Thus I believe the lower limit is more critical for them to be able to measure.

Since the level plug can only measure a single "point of volume" (it's not a dipstick with a range from low to high) I believe it is measuring the low point. This would explain the discrepancy in reported volume replaced by people who measure how much came out (the first time they did it) vs people who go by the level plug.