Hi guys,

I thought I might have slightly underfilled my tranny on the last drain-n-fill. I plugged it right at 50C.

So last Friday I finally got the chance to put Kitty back on the rack and top her up. After starting and cycling through the gears, she took about half a quart (with the internal temp at just under 30C). She didn't dribble very quickly, but as soon as the temp hit 40C (using a laser thermometer on the escaping fluid), I plugged it. Only yesterday did it occur to me that the surging might be gone. This morning I paid closer attention. Yup - completely gone. I could not detect any surging at all.

My recommendation: When topping up the 6H26, plug the tranny right at 40C.

Please update this thread with your results if you try this and had been experiencing surging prior.

 

When I did my refill with SP (two messy attempts), the final top off and confirm required only a couple of oz. I was quite confident that it was as close as it could be. I continued to have the cold ‘surging’. The surging I’m describing is the transmission shifting up and down trying to find the correct gear. Once it is warmed up it is gone. My solution, if you call it one, is to simply shift into 4 until I get into town which takes @ 3~4 minutes. I can then choose 5 or D and the ‘surging’ rarely rears its head again until the following morning (after a nice night’s sleep).
I’m reasonably certain that with 124K on my tranny I’m not going to expend any more time or $ trying to eliminate it.

wj

 

Hi WJ,

Hmmm, .... I haven't heard of the trans hunting between gears before. That's kinda odd. Mine has a 5 mph window between the speed it would upshift to a gear, and the speed at which it would downshift back to the prior gear. It doesn't hunt at all. Your problem might be software related more than mechanical (or hydraulic).

The surging I used to get is when I was in 5th or 6th gear, on a level or slightly inclined road, and maintaining a steady speed. The engine/tranny will repeatedly accelerate and decelerate slightly. At one time it was quite noticeable; you could even see the Tach needle moving up down with the surges. But normally it was something that only an aware driver would notice. It was more nuisance than problem, and it would be gone completely in a little while, but it "was" kinda irksome.

 

Sounds like the on on S-Types: TSB S307-14

However, that TSB seems to say it can be cured and that does not appear to be the case sometimes (ever?) on S-Types.

Appears to be the Torque Convertor not locking up as it ought to.

 

Yeh - a balky torque converter could explain things (maybe). I don't know enough about the trans to make that assumption though. Don't know what would cause it; don't know why it would go away after things warmed up; don't know why it's gone now. All I do know is that it's just gone - WOO-HOO!

 

From where I sit, your description is the transmission slipping. The torque covertor is not 'locked' when in D, that is there is enough slop, if you will, to allow for smooth transitions at small throttle openings.
My surging also shows the engine rpms fluctuating, since the engine is tied to the torque converter and it is not mechanically coupled to the final drive.
In my world if the engine was surging then it would also 'surge', vary rpms, at idle and part throttle in neutral.
Whatever it is, I'm glad yours is gone.
wj

 

I am at 87K miles and just recently starting having this exact same "morning shift toggle" between 6&5 and 5&4. I also do that exact same manual shift for the first few miles and when locked into a specific gear there is no slip so it does not seem mechanical.

I also have the squawk now. The car has already had a new filter/sleeve and some new fluid.

A while back I acquired a liter of the ZF additive on speculation that it would eventually be needed. I am going to try that first. Hoping that both issues are resolved by that.

For now I pretend I am in the next "Fast & Furious" and shift away.

 

I had this exact problem in my 2005 VDP. It was the torque converter and it got replaced under my extended warranty. The dealer tech said he had seen it before too.

 

I had the squawk when I first purchased it, did a pretty complete drain/fill with sp and the squawk was gone. Did another drain/fill and then a top off. I feel as if I have @ 65% new fluid in the tranny.
I bet your additive will handle the issue for many miles to come.
wj