OK folks, I have a tendency to zig when everyone zags but never the less I would like to revisit a train of thought I am currently pondering. I am a layman but I am also reasonably practical.


It's the Aisin 6 speed AWF 21.

Shop manual says to level the transmission fluid at 50 to 60* transmission temp.

The transmission also has a breather so, unless it gets blocked any over pressure will vent.

I simply can't see many garages (including LR) actually doing the leveling 60* temperature thingy as it adds time and most cars will sit for hours before draining. I can see most mechanics putting back exactly what volume was removed since getting the transmission to 60* takes some time. However, depending on who filled it last (if it was ever refilled) that volume could vary and may not even be accurate if it ever was to begin with!

So I ask the Freel2 experts, tell me why one can not simply drain a transmission and refill it to the level of the drain plug even on room temperature fluid? Basically, "what difference does it really make"?

I must confess, I am killing some time but still, it seems like the 50-60* thingy is overly complex and very impractical.

Motion,

If you look up the expansion rate for a typical Hydrocarbon based fluid you will find numbers near

0.1% per degree Celsius (on the high side and about half of that on the low side)



I believe that this should be calculated like compounding interest.

For a 100 Degree change in temperature

Note: this means - 45 C to 55 C and what are you doing changing your fluid at -40 C, turn the heater on already

The change in volume would be 10%



For me a much more reasonable 25 C to 55 C

A 30 Degree change in temperature

The change in volume would be 3%

If we have 10 Liters in the Transmission (actually we have less) then we are talking about 300 mL


I don't even like metric units but I know that 300 mL isn't much.


In fact I would argue that you need to make sure that the vehicle is very level if you want to be accurate to that small amount of fluid. If its not level that may affect you measurement more than the fluid expansion.

I ignore the 55 C level checking and I just replace the same amount that I remove and I have done it this way for 5 changes at about 3 liters per change.

Good luck

Paul

MotionInc wrote:

.....................................Shop manual says to level the transmission fluid at 50 to 60* transmission temp.

The transmission also has a breather so, unless it gets blocked any over pressure will vent.

I simply can't see many garages (including LR) actually doing the leveling 60* temperature thingy as it adds time and most cars will sit for hours before draining............................... it seems like the 50-60* thingy is overly complex and very impractical.

Motion,

You can go down this path

Where you ignore the shop manual

And you make decisions based on

...Common Sense

...Sound Judgment

...and Scientific Principals

However you are not the first to choose this path

And I must warn you where the path leads.

"....and I took the one less traveled by and that has made all the difference" R. Frost


You've been warned

Click image to enlarge

Take care

Paul

300ml is 0.364 US pints to be fairly precise. I doubt it makes a huge difference out a total vol of 14.8 US pints

https://www.onlineconversion.com/volume.htm


1 UK pint is 1.2 US pints apparently - every day is a school day Jules

p_gill wrote:

MotionInc wrote:

.....................................Shop manual says to level the transmission fluid at 50 to 60* transmission temp.

The transmission also has a breather so, unless it gets blocked any over pressure will vent.

I simply can't see many garages (including LR) actually doing the leveling 60* temperature thingy as it adds time and most cars will sit for hours before draining............................... it seems like the 50-60* thingy is overly complex and very impractical.

Motion,

You can go down this path

Where you ignore the shop manual

And you make decisions based on

...Common Sense

...Sound Judgment

...and Scientific Principals

However you are not the first to choose this path

And I must warn you where the path leads.

"....and I took the one less traveled by and that has made all the difference" R. Frost


You've been warned

Click image to enlarge

Take care

Paul

For a second , I thought The Road Less Travelled by M.S. Peck (dated a psychologist for quite a few years a long time ago ) but R. Frost is much more applicable here . The procedure is overly complicated and for 300ml (agree with @jules also) seems impractical since the transmission can vent excess pressure.

It's like the rear diff in these vehicles, since the originals were of poor design and starved the pinion bearing for oil, a slight over fill has to be better than any underfill period.

I remember in my other makes of cars the fluid was measured either hot or cold in fact the level for either was stamped on the dipstick.


I just did a google search on the topic

why should auto gearbox fluid be at a certain temperature for measuring

Quote:

I remember in my other makes of cars the fluid was measured either hot or cold in fact the level for either was stamped on the dipstick.


I just did a google search on the topic

why should auto gearbox fluid be at a certain temperature for measuring

I’ve done mine both ways & it made absolutely no difference to the end result. Of course, drain & refill with same amount does require the level to be correct in the first place. The last change I did cold & added the same amount as removed, then added an extra 500ml. I then drove the car until the temp was just under 60°c. Got home & checked vehicle was level, temp bang on 60°c & with engine idling, removed the level plug & as near as damn it 500ml drained out. (Now Sold). 2008 Freelander 2 (Nazca Sand) SE TD4 Auto. Statutory write off & on WOVR for hail damage but still road legal.
171037Km as of 09/05/22
Superchips Bluefin Flash
Nanocom Evo II (also sold)

jules wrote:

300ml is 0.364 US pints to be fairly precise. I doubt it makes a huge difference out a total vol of 14.8 US pints

https://www.onlineconversion.com/volume.htm


1 UK pint is 1.2 US pints apparently - every day is a school day

Paul, now we need to know what 2 cents equates to? Common sense isn't very common.
_______________________________
2007 Land Rover Freelander2 I6 hse Auto

No, Paul Im not up for discussing the merits of trans-Atlantic volume measurements
But you do get less beer for your pint, but then again it tends to be stronger.

Anyway, I would have thought that if the engine/gearbox has been run so that the gearbox is warm to touch (you can measure the coolant temp if you want) and the car is level, checking the ATF level at this point would be good enough.
Well, that's what I did. Jules

Axel I may have know the answer to your question before the Pints but it is unlikely that I will remember once we get to the Pints.

Motion Now you have your answer. Based on a random sampling of four Land Rover Mechanics at least 25% of the Mechanics do verify that the Transmission is warm when checking the level.

And in case you haven't figured it out Motion you are one of those mechanics. (Now you know why you should always take the blue pill.)

Jules Nice work closing the loop. When talking about what is typically consumed at a pub I do believe that here in the states we are consuming Pints that are "typically stronger". But having said that I would also point out that our neighbors to the north are consuming beer that is typically even stronger than we are.

Canada > US > UK

Take a look where Motion is from.

Well played!!!

Take care

Paul

Last edited by p_gill on 19th Sep 2021 7:46 pm. Edited 1 time in total

Yes, Canadian beer is awesome.