The quest for the disappearing auto fluid

[Mr.Ian]

Yes it's strange problem time again.

Gm400 autobox
After not being run for 2-3 years I was expecting problems here and there but this is really a stumper so far.

Engine cold, transmission fluid level checked and was a little low
1 litre of ATF added and looked better.
Jaguar recomend to check with engine running and after going through all gear selections on the autobox.
Engine started and a quick check on the fluid level with engine running - Not A Drop on dipstick.
So I thought it had maybe drained the torque converter over the years and when started it had refilled it hence the lack of fluid.
So still with the engine running I added another couple of litres of ATF.
Re-checked with the dipstick - Nothing.
Turned the engine off to have a think and after a few mins checked the autobox level again.
Now it's level is overfull
Oh bloomin eck.
Started the engine again took the gearbox dipstick out straight away, wiped it clean and checked the level. - Nothing
Gearbox appears to be working ok as far as I can test it (as the car is on stands) as in it drives the wheels ok in all positions.
Fluid is clean and clear.
Checked the vacuum line incase it was being sucked into the engine (if that's poss) but all's ok there.

The level reads too high now but if you start the engine and check the level again there's nothing on the dipstick at all???????Turn the engine off and check the level straight away and it gradually builds to overfull and has minute bubbles in it which indicate it's overfull.

And yes i've looked on the floor and it's not there either.

I'll be trying the car off the stands during this week up and down the drive and see what happens when it's under a slight load, maybe even a stall test if all looks ok drive wise.

But has anyone got any idea's ?

[iain1980]

Could this be the torque converter filling up and emptying as the engine is run?

There is a valve inside that can stick, meaning it will empty immediately after the engine is stopped. The seal can also let air in without leaking oil out.

The level when the engine is not running gives really random readings, it is no help as to how much fluid is in there. Also when cycling through the gears the wheels should be still was this the case?

Having said that, the fluid must have been really low to start with - so where did that go?

[Mr.Ian]

Thanks for the reply, just to clarify a few unclear points.
The gearbox has a small leak (think it's from the dipstick tube seal) so over the years it will have drained to that level (and if the torque converter drained also it will have lost a lot of fluid).
When I was saying i've checked the floor I was meaning there's no fresh fluid there.
So if the torque converter (with a fault) does ever drain it's fluid then that sounds like it could very well be the fault.
So in which case i'd have to get a very high level in the box cold as it would need to fill the torque converter on each start up.
I'll get another couple of litres of fluid and try to get a level in the box while the engine is running.
As the car is on stands (and also has no brakes yet as they need bleeding) as soon as I put it in drive the wheels turn and as Jaguar state to hold the car still with the brakes I can see I did this wrong.

Looks like you've hit the nail on the head with the sticking valve in the torque converter though as that would certainly cause these results.

I'll sort the brakes and get some drive pressure in the box and see if we can get a result and fingers crossed maybe a bit of heat in the box might un-stick the valve. !!!!!!!!!!! Can only hope eh?

Cheers.

[Mr.Ian]

Ah yes just found it on the parts list, there's a front seal that seals to the torque converter and if the torque converter gets removed from the box this seal lets the fluid out of it. So it looks like it could be this seal that is draining the converter back into the box.
Oh poo
Autobox out just to replace 1 flippin seal.
Tha last one I removed (from a Merc) was flippin heavy to say the least.

Might leave it on my never ending and vastly increasing '''to do'' list as the car's not on the road at the moment anyway.

[Mr.Ian]

Looks like there's a result with this problem (fingers still crossed) ,
Checked the fluid level and there was a high level on the dipstick.
Started the engine and checked the fluid again and there was nothing on the dipstick.
I added another 2 litres of fluid and there was a level with the engine running.
Turned the engine off and the level appears to be ok (ie not gone to overfull as it was doing).
Maybe the torque converter needed to be filled completely to hold it's fluid? and with a partial fill was draining itself?
Or maybe whatever holds the fluid in the torque converter that might have been stuck has now become unstuck ?????
No idea really
But from tonights' findings/results all appears to be ok
(fingers still tightly crossed)

[Mr.Ian]

Obviously didn't have my fingers crossed tightly enough, torque converter is still draining back into gearbox .
Not sure if this will cause any problems apart from a very very high level in the box when engine's not running.
Box appears to drive ok but I can only drive it back and forwards on a 2 car length drive, so i've no idea as yet if it'll change gear.
As the level drops back to normal when the engine is running i'm going to leave it as is for now and get on with other bits that need sorting.

[iain1980]

With use it may free up and fix itself! ............ It would be the first time though!

I wouldn't commit to pulling the whole lot out for repair untill it has driven at least few miles anyway as I sure you would rather find out if it has any other issues before rather than after.

Next time put an elastic band around your fingers so they stay crossed!

[steve_m]

Hi
I know that this is an old topic but did you get any results as I seem to have the same problem?
Steve

[almcl]

Steve

It may be worth mentioning that you can't check the gearbox oil level cold nor with the engine off. It's got to be on level ground, properly warmed up and with the engine running.

Even then the V12 box (which is what was being described above) is an absolute swine to get an accurate reading on as the serpentine curve on the dip stick usually results in two different levels, one on either side of the dipstick.

Are you having problems with your V12 or your 6 cylinder car?

[steve_m]

Hi
It's the V12. Checked it last week after a run and there was just a trace of fluid on the bottom if the dip stick.
Left it for a week as didn't have any ATF, checked it today and the fluid was about 2" up the flexi part of the dip stick (when cold). Then I remembered this post.
Took it for a 20 minute run, checked again with the engine running and it was about normal.
The car seemed to drive ok and the fluid is clean.
I'm off again for another week so I'll have another look when I am back.
Steve

[steve_m]

Checked it again today after a week and the fluid was about an inch up the spiral part of the stick (cold).
Took the car out for a run, checked it again and it was normal. Took it for another run, checked it again, normal.
Put some Wynns in it and crossed fingers.
Steve