D2 TD5 Autobox diagnosis

Is this on a level road or up a hill.
If up a hill it is normal if unlocked as the stall speed of the TC is 2800-2900 RPM.
All other things can remain constant.

If on the flat it would be very unusual., but it is likely be Torque Converter related.

My experience with Trimatics and others suggests that anything that is related to oil pressure in the trans itself will cause it to change back a gear or more just cruising along. If the clutches are gone I would expect it to Flare on changes . Another test is the time taken for the trans to engage when shifted from D to R. A long time is bad.
Although these tests refer to old transmissions the principles of autos are pretty standard. Just these days with fancy electronics they can engage 2 or more ratios at once, thus giving say 6 speeds or more from an actual 4 speed set of gears .
Regards Philip A

I wouldn't rule temperature out just yet. Plotting the temp fields against speed fields and manifold turbo pressure, shows that the pattern you are concerned about occurs during the warm-up period and disappears once once the coolant temp (Brown line) has stabilized. (Note Y axis is logged and gaps in road speed are zero values).

https://www.aulro.com/afvb/images/im...015/04/887.jpg

I'm not full bottle on Auto transmissions or Turbos, but could it possibly be engine related or and an electrical comm issue rather than transmission???

Another idea is to log the data over the same route with the engine warmed up first.

Cheers

Steve

Pretty level, no discernable gradient.
I can't imagine getting the test without being in the warm up stage to some extent, just idling would take forever to get there.
There is a chicken and egg as well on some of that, if you replicate the revs, say go for a drive and keep it in second (I reckon that would give you 3000 for 60kmh) then the engine will be heating up.
I can actully stop this from happenning by just stopping and letting it work through the gears again, or by manuually changing to force a bit more action in the box.
I reckon I might try and ping Dave or his son over on LR4X4 to see if he has a definitive diagnosis.

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steve_a,

Is Rok_Dr's plots and analysis fair and consistent with your experience? That points to engine temp determining if the gearbox should go into lock or not. What other diagnosis are you looking for?

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Originally Posted by slug_burner

steve_a,

Is Rok_Dr's plots and analysis fair and consistent with your experience? That points to engine temp determining if the gearbox should go into lock or not. What other diagnosis are you looking for?

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Not really, the period of time/speed is not when lock is expected and I wasn't looking for it to lock, it's only 60kmh. I made a point on the way home last night of running the car is the first few seconds to a higher rpm in 1,2,3 and also coming to virtually a complete stop.
The same stretch then saw it behave and do the expected 2000rpm after that even though the engine would have been at the same temp.
This just points to hydraulic pressure to me, so crap in the solenoid seals or similar.
It may be that there is more than one issue, e.g. poor oil pump, worn clutches which makes a diagnosis tricky due to interactions.

Electrical issues are tricky, if it only happened in the wet say then I'd be thinking that maybe it is a loom issue, but nothing is pointing me that way at the moment.
Engine issue, not this fault, though I do wonder if it is putting out 100% power, my tuned-up-a-bit 300tdi would seem to give it a good run for it's money, till it runs out of gearbox :)


I was hoping (as in first post) that someone knew which area(s) of the box were the likely cause so I could see if triage or full fix was the way to go.

For once the Rover was helpful and did the same thing on the way in to work on the same stretch as out. Not as pronounced, but was accompanied by a surgeing feeling, it was like clutch slip in a manual but was oscillating.
Also accompanied by ATF smell. On checking, it had spat some fluid out of the dipstick (I added one a few months back).
Level is about right and the dipstick is the only source of ATF I can see.

So, more evidence for hydro but no idea of actual cause...

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On the plus side it has had lots of new fluid..., I flushed the cooler a few weeks ago and I did the filter as well before the pipe failure.

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I am wondering if you have crushed/misplaced the o rings that connect the filter to the valve body and it is leaking. Spitting up the filler tube suggests that the fluid is getting back into the sump but not being sucked out.

It may be worth a look before you go spending big money.

I think you would have more than one symptom like flaring changes, slow engagement, etc if there was something mechanically wrong. Sometimes the best course of action is to relook at things you have recently touched.
Regards Philip A

Not a bad thought, but I have done nearly 10k km since I replaced the filter, and that should exhibit an issue all the time in terms of lack of drive because of no pick up.

I still have my hose clamp fixed front cooler pipe, but I'd more expect that to cause aeration or some other issue once warm.

I noticed on the way home that 3rd gives 2100rpm for 60kmh, while 4th gives at best 1800, and often closer to the 2100. Having given up with 4th (unlocked) on the way back it seemed a bit happier, so I'm wondering, not surprising, if 4th is toasted.

There are a bunch of other symptoms, sometimes it doesn't pick up drive from stationary, though once that was definitely fluid level, harsh downshifts (audible clunk as you slow down and the gear engages), I happened to shift straight from D to R the other night and it seemed to take an age to engage.
I swear that pushed hard there is a 'roaring'/whoosing noise as well, almost like the torque converter is pumping heaps of oil for little effect.

To me the take up for drive doesn't and hasn't ever felt right, with a noticable lag as your rev up (like 0.5 second lag from foot down to motion, even though revs rise during the time), makes it feel very sluggish till at least 2500.

On the soft sand at Lake Bonney at easter I noticed that it just didn't drive like I expected, I thought I was losing traction, only to look out and find that nothing was going yet.. despite low range locked.

If only I could have got the manual.. but the missus wants the auto...