Xantia 1.9TD AL4 pressure regulation fault, an update

[masood_ilyas]

1997 Mk2 Xantia 1.9TD AL4 automatic, 145k
This car was giving intermittent flashing snow flakes with limp home mode, Lexia reported this as a pressure regulation fault. Several threads suggested changing oil, this was done using the proper Esso/Mobil LT71141. What came out was clear reddish purple colour fluid with small amount of very fine metal dust. It was used by the gearbox specialist of some repute who assured me at the time of rebuild that their oil was correct as recommended by Renault in their DPO boxes!. Any how, two changes costing almost £100 pounds later it was a joy to drive to work (12 miles or 30mins) with no faults.
This state of happiness unfortunately did not last much longer as now having driven it on a longer run another problem came to surface. So I connected the laptop and Lexia to record the test run. As before I experienced smooth gear changes and plenty of pull but only when the oil temperature was below 84degC. Minor bumpy gear changes took place between 84 - 89 and the driving was stressful above 90, a complete lack of drive as if in neutral when changing down at a stop, it required revving up the engine followed by rear shunt like effect to move on, and jerky changes from 2 to 3. Reverse gear was also behaving the same way as N to 1

The question now is,
i) is it the clutches and brakes needing change, despite the fact they seem to work fine when the oil was cold with lots of pull.
ii) or is it the hydraulic block leaking oil when hot unable to divert fluid to significant parts.
Chinese spare providers are showing bushes and solenoids for rebuilds but being an AL4 virgin I do not know if this is the correct route to take.
I may take on a risky venture of taking the hydraulic block out for a thorough clean.
I wonder if the red stuff (Dexron?) over the two years period has done its damage and this is now beyond economical repair.

A Somerset gearbox builder thinks it is the E1 clutch, bushes etc but then he may be looking for work and not interested in offering other solutions.

Any advice the knowledgable ones can offer will be most appreciated.
As always much obliged,

Masood

[Clogzz]

Renault uses Dexron III in the DPO box.
There were stories of cracked castings in the AL4, where the pressure would escape through the insides of the casing.
There’s been a modification to replace two electrovalves with Borg Warner types that have a black socket and large bypass.
The modification needs a software update.

[ex-vaux]

Could it be a low pressure fault due to a low fluid level?

Did a full fluid change on my 406 auto, AL4, about 300 miles ago. Used the LT fluid and an 'stopslip & seal' additive by Lucas (700ml off ebay).

When I drained down the box the black fluid that came out did not fill me with confidence!

I re-filled the box, as per the instructions, using the inner level plug. The box only took about 2litres of fluid including the additive before it appeared to be full!

So I took her for a run to get the box warm and try it. Within about 20 miles, I got the snow flake lights and an auto box warning. Limped home and decided to add 200ml more fluid as I felt it should really have taken more, particularly as about 3 litres of black death had been emptied out!

Tried it again and it ran much better with smoother changes, no warning lights or warnings! but I was still not happy so left it over night and tried it first thing. Got a bit of jerky-ness until it warmed up then was fine.

Decide to add another 200ml and see. Tried the same thing again, leaving it over night and it had improved further. Added a final 200ml and gave it a good run, 150+ miles with good mostly smooth changes. The additive by now will have started to do its job and will probably help the clutches, etc.

Now in a car thats just clocked 170000 miles, I am not unhappy with its performance. It is quiet and as smooth as any auto I have owned. The engine is like a swiss watch and pulls well too.

I also noticed that kick down has improved significantly, suggesting that fresh fluid has pleased the torque convertor.

I appreciate this is not the best or recommended method of refilling the AL4, but in point of fact, its supposed to be 'sealed for life', left to its own devices! So changing the fluid is something PSA have washed their hands of. In reality, reach 150000 miles and your doing well!

In any event, I may have preserved it for another few miles for not much time or money!

[masood_ilyas]

Thanks for the info Clogzz and ex-vaux.

So there is some hope that it might still be a hydraulic block issue.
Any idea where this upgrade software can be sourced from or is it Stealer only job.
Lexia suggests it is possible to upgrade Engine and gearbox ECUs but it did not come with any extra software.

I did have a look at Citrojim's homepage and his stripping and rebuild, it is very informative but alas it is not for an AL4.

I will keep searching the net for more information, it might come in handy for our forum members with AL4s

Thanks.

[CitroJim]

Sorry Masood but I know little of the AL4. All i can say is that my HP20 strip does generally apply to the AL4 as well.

One observation is that it looks like yours was filled with DEX judging by what you drained...

One very striking difference between DEX and LT is it's viscosity. LT is quite thick and has real 'body' whereas DEX is more like water. I'd say that as the 'box warms up the pressure is falling as the oil thins. As LT is thicker to start with, the rough changes take longer to become apparent with LT...

I'm also of the opinion that DEX has inferior lubricating properties and you may have some generalised wear but more than likely I'd suspect the pressure regulator electrovalves as these seem to be quite a common problem.

One major difference between the HP20 and AL4 is the use of brake bands rather than the all-clutch construction of the HP20. To determine exactly what's going on you need to know what bands and brakes are engaged in what gears...

I have a copy of the AL4 training notes that would tell you that. It's too big to post here but I could perhaps email it to you...

[addo]

I have to order some more Chinese upper electrovalves ASAP, perhaps a pair can be sent on to the UK?

[masood_ilyas]

Thanks for your suggestions chaps.

It is now obvious that the next logical step is to tackle those solenoids.
Apart from the AL4 rebuild guide and purchasing the solenoids I will need to upgrade the gearbox ECU software.
One of the Lexia screens shows the download dialogue but I am concerned about letting it loose on the net in case it called home and got disabled as a response for being a chinese purchase. I need to solve this software issue first before purchasing anything else

Given that there is also sign of wear due possibly to poor lubrication properties of non Esso/Mobil fluid,
there might be some thing in the suggestion of additive to plug the leaks like this one on ebay.
I hope this will not create more problems later due to mixing of fluids and frothing etc.

Thanks
Masood

[ex-vaux]

That's the one!

Got a 1000+ mile run over the next week with the 406, so will see how she runs with the fluid change and additive, post back the outcome!

[ex-vaux]

Just a thought Masood, the Haynes manual shows someone using a ball joint splitter on the the selector cable ball joint on the gearbox!
Seriously over kill for this job. Not needed! Simply unbolt the 10mm pinch bolt on the selector lever on the selector unit itself.and lift it off exposing the gearbox filler plug......... appreciate I may be teaching you to suck eggs and that you may not even use a Haynes, but......

Citrojim, would it be possible to have a copy of the notes you have on the AL4? Many thanks

Ian