Query changing auto gearbox oil

[pete 75]

Hi All,i have a 2006 2.0 litre cdti auto with only 62000 miles i am the second owner and have a fully documented service history from new.Although the gearbox was working fine i thought it was about time to do a gearbox oil change which i duly did following the very usefull how to by beinet 1,this is the first time an oil change has been done.I managed to drain 7.1 litres of old oil which i replaced with the same amount both were carefully measured,when i did the final check by taking out the level plug i was surprised that half a litre cameout,i warmed the gearbox up as recommended and the car was dead level any body ideas apart from being overfilled by the factory which i find hard to believe.Thanks Pete

[lightningmark]

Originally Posted by pete 75

Hi All,i have a 2006 2.0 litre cdti auto with only 62000 miles i am the second owner and have a fully documented service history from new.Although the gearbox was working fine i thought it was about time to do a gearbox oil change which i duly did following the very usefull how to by beinet 1,this is the first time an oil change has been done.I managed to drain 7.1 litres of old oil which i replaced with the same amount both were carefully measured,when i did the final check by taking out the level plug i was surprised that half a litre cameout,i warmed the gearbox up as recommended and the car was dead level any body ideas apart from being overfilled by the factory which i find hard to believe.Thanks Pete

How did you check the temperature before you checked the level? Possible it was too hot which has an effect on the volume


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[pete 75]

I have a temp probe and it was 32c

[75driver]

I don’t know the exact volumetric coefficient of thermal expansion, for atf,
But for the sake of doing an approximate calculation, let’s assume it is 0.0007 / deg C (as listed generally for engine oil on the internet).

Approx 7 litres ATF measured at and added at 20 deg, may rise to say, 60 deg before drain plug opened.
(20 deg oil will mix with the remaining warm oil in the box, so I’m just using 60 deg for sake of argument).
Volume increase = 7l x 0.0007 x (60-20)deg = 0.196 litres, or approx 200ml.

Conversely, it will also depend on what temperature the “drained oil” was measured at.

In an ideal world, if the drained oil was let cool to room temperature, before measuring its volume, the volume you put in (measured at room temperature) should equal the volume drained, assuming it was at the correct level in the 1st place.

Please nobody use these figures for deciding on how much oil to put in.
That’s what the overflow plug is for.😄

Anyone on here in the ATF business, that knows the coefficient of thermal expansion??



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[75driver]

Ps..any tips on how to remove the hose to the oil cooler?
I had bother the last time I tried to do it.
The 3 plastic prongs on the hose connector just didn’t want to “go over” the lip of the stub on the oil cooler. 🙄
Not much room in there to try to prise them over the lip either. Could be done, if you had a 3rd hand in the centre of you forehead I suppose.😳


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[Jim Jamieson]

The difference between a cold gearbox level and a hot level would barely fill a thimble !

[pete 75]

The difference between a cold gearbox level and a hot level would barely fill a thimble

my thoughts

[SD1too]

Originally Posted by pete 75

I have a temp probe and it was 32c

If you’re interested in the correct temperature MG Rover’s technical bulletin says it should be between 35 and 40 degrees C. The accurate way to measure this is by using the gearbox’s sensor whose resistance is available for measurement at the multipin connector.

However, before we had diagnostic computers and ECUs, transmission fluid level was measured on a dipstick with the gearbox “at normal running temperature”. It was not a precise science and we did not have a national crisis of wrecked automatic gearboxes as a result! You can draw your own conclusions.

Simon

[grout20]

Hi all

A summary of my ATF Fluid change for info....

Rover 75, 2.5 V6, 2001 61000 miles and based on beinet1's excellent thread. All figures are give or take a little bit......

1. Took the car for a 10 mile run up to normal temp.
2. Lifted front of car, although it wasn't level at this stage .... it was down at the front slightly on my drive.
3. Opened the ATF Level Plug first (5mm Allen Key) and was a bit surprised / alarmed that 1.5 litres of fluid came out! Assumed it was related to the angle of the car, or perhaps overfilled before...? Odd?
4. Removed the Gearbox Sump Plug. No swarf attached which was nice ... and a further 2 litres came out. So, 3.5 litres so far. Fluid was dark red and very runny ... not like black treacle as some have reported. It was pretty warm though. Refitted Level Plug. Refitted Sump Plug but forgot to renew the bluddy washer (£6 for a new washer .... one flippin' WASHER! .... from Rimmers ... and I forgot to fit it! Der.... )
5. Added 4 litres of new Smith & Allen ATF402 fluid. Drove front wheels onto a few extra bits of thick plywood until the car was level. Used a spirit level resting on the open door sill and on top of the chrome trim along the rear wing to check the level !
6. Disconnected the Oil Cooler pipe.
(Note for 75driver .... yes it is tricky ...I squirted WD40 over the connection and gently teased the retaining plastic tongue you can easily see/get to over the "lip" with a small screwdriver. Just enough to enable you to slowly wiggle the rest of the connection over the lip and off the stud. If that makes any sense?!)
7. With a 12 inch piece of hosepipe slid onto the exposed oil cooler stud, and fed into an old plastic 2 litre milk bottle, I ran the engine for about 10 seconds. Another 1.6 litres came out.
8. Added 1 litre of new fluid.
9. Ran engine for approx 10 seconds. Another 1.2 litres came out.
10. Added 1 litre of new fluid.
11. Ran engine for approx 10 seconds. Another 1.2 litres came out.
12. Added 1.5 litres of new fluid.
13. Ran engine for approx 8 seconds. Another litre came out. Getting redder fluid out.
14. Added 1 litre of new fluid.
15. Ran engine for approx 6 seconds. Another 0.8 litres came out. Pretty clear, new, red fluid now.
16. Added 1 litre of new fluid.
17. Re connected pipe to oil cooler.
18. Started engine, foot on brake, went through all gear positions twice holding each position for 10 seconds, then back into Park.
19. Kept engine running until the oil cooler casing was quite warm to the touch (no idea what temperature that is ... but was after 3 or 4 minutes)
20. With the Level Plug removed again, a couple of drips came out. I added about 200ml of fluid and it almost immediately started coming out of the plug.
21. Waited until it stopped and tightened up Level Plug, refitted the rubber Filler Plug and Air Filter box (removed at the start)

Took the car for a drive and the gearchanges were definitely smoother.

Well chuffed!

Well done if you've read this far and stayed awake. Sorry for the long thread but hope this is useful, and gives others the confidence to do it.

Couple of pics attached. One showing the color of the old fluid, and the other showing how I stacked up 3 funnels to make the filling up pretty easy.

Happy Roving...

John

[pete 75]

Thanks John very usefull post.Pete