D3 auto hunting gears randomly

[Bulletman]

Gday All,
So my D3 195k on clock , on its 4th gearbox oil fill with filter changed as well, has about 7000ks on this oil which is penrite BMV ?. Noticed it on a very undulating road going down hill with 3t van on the back it would change gears very rapidly causing tacho to rise/fall about 300 rpm. Speed was about 60ish and at first it put it down to the weight of the van pitching on the back. Drove about 400ks that day and never seen it do it that bad again but a couple of times on similar road condition it moved about 150-200 rpm @80-85km/h.
Just been for a drive tonight coming back from cable beach and it did it to me with no trailer and I could definitely feel it changing gears, I assume between 2 gears or 1 and o/d maybe. I have a hawkeye which I plugged in and no gearbox faults are logged. I did have a engine fault, something to do with fuel pressure out of range , but I never had any issues with faults since we left Darwin so it possibly could have been old fault.
We drove thru alot of water at el questro so I'm wondering if water has got in somewhere, as when I was leaving I got the dreaded slow to raise suspension fault, so did drive thru several crossing at normal height.
We are in broome so chances of getting anything here is minimal as it's not a toyota so plan to continue south . Was thinking of seeing if I can get a couple drums of bmv to have incase , but no gearbox temp faults or similar make me think it's more of a water ingress issue not gearbox oil.
Suggestions or ideas please.
Cheers Bulletman

[Bulletman]

It seems from my reading on the uk site my issue is what is referred to as the shudder.
Seems Dr Tranny is a additive that has worked but doesnt look available from any of the normal parts sellers. Repco, supercheap etc.
Bulletman

[Eric SDV6SE]

Have you checked you've got the right fill level? Sounds like you may need a valve body rebuild too. If solenoids are dirty, they don't provide enough line pressure to hold the gear / clutch pack

[River]

Repco and others should have this
Lubegard Instant Shudder Fix 60ml - 19610
SKU: A9417139

[Bulletman]

So a check this morning sees the oil level low, maybe added 500mls, not convinced that small amount of oil will be my issue but I found something. I fitted a new radiator before leaving darwin so possibly didn't check it correctly but not sure why it would have been low, definitely no leaks that I can see.
Will pick up some of the suggested shudder fix and some extra oil and see how we go.
Bulletman

[PerthDisco]

Check tranny cooler hoses on side of radiator near coolant bottle are not leaking if the radiator was changed and also the old radiator would have a quantity of transmission oil in it when removed.

[Bulletman]

Check tranny cooler hoses on side of radiator near coolant bottle are not leaking if the radiator was changed and also the old radiator would have a quantity of transmission oil in it when removed.
Yep I checked those hoses plus every other hose for about the first 5 days after I changed it, also had a look again today seems all dry.
Will keep an eye on it.
Atleast i found something, might actually get some sleep tonight
Bulletman

[Dagilmo]

It seems from my reading on the uk site my issue is what is referred to as the shudder.
Seems Dr Tranny is a additive that has worked but doesnt look available from any of the normal parts sellers. Repco, supercheap etc.
Bulletman

I have some in the shed. I'd be happy to pop in post to you if you want.

[Bulletman]

I have some in the shed. I'd be happy to pop in post to you if you want.

Thanks kindly for your offer, I purchased some oil and some shudder fix today at repco in broome so see how it goes tomorrow when we hook up and head off.
Fun times ahead. Thanks again for the offer.
Cheers Bulletman

[Ilike2disco]

Is this transmission judder the lock up feature of the torque converter locking and unlocking in response to changing loads?

I’ll have to read more I think to educate myself better on this.

[Bulletman]

So travelled 400ks today and certainly a noticable difference with the correct oil level in the gearbox. It wasnt perfect, still hunted around the 70-80km/h range but it hunted about 100rpm not the 300rpm from the other day.
Personally it feels to me it is 5th gear changing in out of O/D, but it could be slipping.
I'm not going to add the shudder fix at this stage as I found I could out drive the shudder above 80ks and maybe I'm over thinking it but have read of a few on here needing s gearbox reflash after adding dr tranny and the gearbox went into fault mode.
At 80 mile beach for now and if I have issues I will wait till we get closer to whyatts in geraldton before I add the shudder fix as my Hawkeye doesn't reflash .
Will need to invest in an iid tool but first need to catch a fish or 10 here.
Cheers Bulletman

[Tombie]

Likely the TC lock up failing.

[Eric SDV6SE]

Is this transmission judder the lock up feature of the torque converter locking and unlocking in response to changing loads?

I’ll have to read more I think to educate myself better on this.

The judder is from wear in the torque converter lock up clutch plates and it not being able to lock up under constant load. Basically the lock up mechanism is a steel diaphragm spring hydraulically activated. This pushes on a set of clutch plates to lock the input and output shafts mechanically. Wear in these plates and the fluid ports due to contaminated fluid means it can't reach the right pressure to move the plate spring. Most of obvious when under constant load (e.g. towing) and engine rpm varies or "flutters". Regular fluid changes and using sport or command shift to keep the engine rpm above lock up speed (1250rpm on the 2.7 and 3.0l diesel) will look after your tc lock up plate. An additive like Dr. Tranny is a friction modifier and just a band-aid. These tc are rebuildable, should cost around 500 bucks, the rest of the cost is getting the transmission out of the vehicle. A new genuine tc is around 2500-3000.

[Hoges]

One from left field: how long since you've cleaned/replaced the MAF sensor and pre-/post CAT oxygen sensors?
Their outputs coupled with the throttle position sensor output can affect the auto transmission change points. I discovered this years ago in RRP38...the 4sp auto on the P38 would drop back to second gear on the slightest incline rather than choosing third...even though I reset transmission numerous times with the "BlackBox/Laptop" it was to no avail and was driving me nuts.... I discovered that a few sprays of the MAF with CRC cleaner made an enormous difference ... it improved even further after I'd replaced the MAF and O2 sensors on the P38 and reset the adaptive values....
I'm not saying this is your issue... just another consideration...[wink11]

[Tombie]

One from left field: how long since you've cleaned/replaced the MAF sensor and pre-/post CAT oxygen sensors?
Their outputs coupled with the throttle position sensor output can affect the auto transmission change points. I discovered this years ago in RRP38...the 4sp auto on the P38 would drop back to second gear on the slightest incline rather than choosing third...even though I reset transmission numerous times with the "BlackBox/Laptop" it was to no avail and was driving me nuts.... I discovered that a few sprays of the MAF with CRC cleaner made an enormous difference ... it improved even further after I'd replaced the MAF and O2 sensors on the P38 and reset the adaptive values....
I'm not saying this is your issue... just another consideration...[wink11]

Good logic, however this one is Nothing like the P38 transmission.

As Eric detailed. The TC clutch is playing up.

[Bulletman]

The judder is from wear in the torque converter lock up clutch plates and it not being able to lock up under constant load. Basically the lock up mechanism is a steel diaphragm spring hydraulically activated. This pushes on a set of clutch plates to lock the input and output shafts mechanically. Wear in these plates and the fluid ports due to contaminated fluid means it can't reach the right pressure to move the plate spring. Most of obvious when under constant load (e.g. towing) and engine rpm varies or "flutters". Regular fluid changes and using sport or command shift to keep the engine rpm above lock up speed (1250rpm on the 2.7 and 3.0l diesel) will look after your tc lock up plate. An additive like Dr. Tranny is a friction modifier and just a band-aid. These tc are rebuildable, should cost around 500 bucks, the rest of the cost is getting the transmission out of the vehicle. A new genuine tc is around 2500-3000.
Great explanation, annoying tho as I have not done much towing before now and done no more than 50k between services on the box.
I'm thinking a lack of sports mode use and the car doing on average very little kms in normal daily use. Would be lucky to do 100km a week , then 1 or 2 times a year do a trip that would cover 7000 or so kms.
Anyway it is what it is and as long as it gets us to Perth I will get it sorted there
Cheers Bulletman