Thread: Another ZF auto issue.

Hi Neavesie,

You do know that you can only undo the fill level plug with the engine running and all the gears primed by running through the gears? If you just undo the filler level plug without the engine running you will loose a lot of fluid as you have experienced. Maybe you did not have enough fluid in there in the first place. You need to now do a change and fill it by the book and see how you go.

Well that would explain it, I thought it just had to be running to fill it.

As far as the amount of fluid required, when I first got my Disco I topped it up without the engine running (I didnt know then), that was enough to stop the slipping the first time. But I will top it up properly and test. Got a bad feeling though.

With the burnt fluid I think this could be a result of the cooler being too small for the new torque converter. Correct me if im wrong but a P38 cooler can be used as an upgrade.

or just add another,,
lots of info on here-

I can't answer your question about the torque converter, but if you are doing heavy towing, are you using 3rd gear lockup as this reduces heating of the trans fluid considerably and improves driveability at towing speeds. The TC will lock at about 76Ks and stay locked down to about 60 in third.

Just standard driving (but before I owned the Disco it was setup to pull a big caravan). The heavy duty TC requires more torque from the engine hence more pressure on the auto, I just didnt expect so much heat.
I topped the auto up and it still slips and changes rough. Looks like a trip to my local auto specialist before I try anything.

Wish I had bought a manual

My beloved Disco, I cant live with it and I cant live with it.

your logic is a little off...

the stall speed of the TC is simply the speed at which maximum torque multiplication occurs.

lowering the stall speed makes for smoother less aggressive driving IF you have the engine torque to make it work. if your engagement is not smooth, and you have the torque if you are overloading the TC and forcing it into slip all the time then you are baking the oil and shock loading the clutches every time the lockup engages because of the "slip" speed between the "fluid coupling" speed and the speed at which physical lock up occurs.


raising it makes for more agressive driving and prouces more torque by substituting more RPM and lower torque. IT also provides a longer "Ramp up" of the applied toque coming out of the TC, this is harder on the fluid and the clutches for applied power and holding BUT usually you have lower "slip" speeds between the fluid coupling and mechanicical lockup. raise it high enough and you'll get massive shockloads on the auto because you'll get very little drive coming through the torque converter untill the internal hydraulicy magic gets up to speed and then all of a sudden you'l get a massive hit of torque.

you can also, within reason, mess with the torque multiplication numbers, more multiplication tends to be more savage on the uptake, provides a steep output torque curve, creates a lot of heat while getting up to speed but does so quickly. Less multiplication is easier on everything BUT because it takes so long to get everything up to speed you cook the oil by applying less heat for a lot longer. its also less fuel effecient overall as you spend a lot longer trying to get into lockup and in lower gears.

regardless, more cooling is always a good thing, as is progressive oil changes

Thanks for the info.

also the oil should be checked when cool not after a drive as this will raise the level.