AL4 Transmission Issues

Hi All,
I've just joined the C3 owners club and thought I would share my experience with the AL4 gearbox on my wifes C3.
I purchased the C3 a week ago because my wife is having driving lessons and thought it would be a good idea to purchase the car so she could get more experience on the road.
The car only had 25000 miles on the clock which was backed up with history and was in very good condition, but was being sold with a fault on the auto box, the fault was described as when it had warmed up was hesitant at changing gear.
I got onto several forums to search for the fault as I had no experience with Citroens let alone auto gearboxes, after trawling through loads of posts and video's I finally came to the conclusion this could be down to the two valves on the hydraulic unit in the gearbox.
So I purchased the car confident I would be able to fix the issue having had lots of experience around cars in the past, I collected the car and started driving home which was some 80 miles or so, the car performed well for around 15 mins but sure enough as described it started struggling to change gear and kept giving a loud thud when it did change.
Most of the journey was on motorway so thought it would be ok once I reached the motorway and luckily it was, got home with only one issue which was a momentary engine warning this only flashed up for 5 seconds then went off, phew.
Once home and the the car warm at this point, my wife wanted to go for a quick run as she was excited to get her 1st car so I agreed to take her for a run down the road and back. To my surprize the car struggled to get off the drive with almost no drive once on the road it seemed like the car was stuck in third gear but made it down the road and back.
I read through the documentation and found the car had originated from north Wales and having previously enlightened myself to the AL4 woes the first thing that popped in my mind was WET with PUDDLES.
Anyway I purchased some Valves from Ebay and 20 litres of Mannol Universal oil which conforms to Mobile LT71141 in preparation for the repair.
Parts arrived time to start the strip down, I found the hardest part was getting to the 16mm bolt on the side of the ECU bracket and I didn't have a 16mm spanner but my trusty old spanner set had a 5/8 which did the job perfectly.
Once the ECU was off it was really easy to get to the gearbox cover plate, so I did a complete oil drain and carefully measured how much il had come out which was about 3.5 litres NOT what was expected, about 1/2 a litre over. I inspected the oil which was dark grey not what you would expect from a gearbox with only 25000 miles, yes you guessed it WATER.
Anyway I persevered and carried on with the removal of the front plate, once removed my suspicions were confirmed WHITE SLUDGE.
So to try and cut this short I removed the hydraulic unit and pulled it apart, cleaned all parts on paraffin and reassembled with the new valves, when putting the manual spring back on I wasn't too sure how to set it up but assumed that as the selector and cam had not moved I would put the spring back in the same position it had been removed from.
I put 3 litres of oil into the box run the engine and kept putting it into drive and reverse to get the box up to temp then checked the level, about 500 mls of oil came out before it started to drip and replacing the drain plug so about 2.5 litres of oil added, a big difference from the 3.5 litres that came out so I would assume about 1 litre of water, WOW that was a very big puddle.
So here goes the test drive, got about 1/4 mile down the road everything working as it should then, OH NO the dreaded snow and sport lights flashing and gearbox in limp mode.
I assumed water contamination of the new oil as it would have mixed with the oil in the torque converter, so did another oil change and another and another, this made no difference still had the S and S warnings flashing up at various times but seemed to be when going into third gear.
So dug out my old Lexia unit that I'd purchased years ago for my sons Peugeot, the software only works on Windows XP and I have Win 10 this meant I had to set up a virtual XP machine on my laptop, what a pain.
Anyway plugged it into the car and pulled up the fault codes, it had registered code 6 pressure regulation, difference, I was a little confused as this would normally be caused by the electrovalves which I had replaced.
Time to take a step back and think through what had been done, I didn't have the S and S warning flashing before but do have it now, wrong oil or something wrong with the new valves????? I would have to take the hydraulic unit back out and check my work.
Removed the unit from the gearbox (only took me an hour this time as opposed to 4 hours the 1st time), I checked the valves with a 12 volt supply and they were working so I decided to check the old valves which I had previously removed, they were also working but a distinct difference in strength of the click. The new valves had a very strong click but the old valve were much softer and were Borg Warner originals. I made the decision to replace the old valves as they didn't give me the S&S fault, cleaned everything again an reassembled and refilled with oil, so glad I got the 20 litres.
Road test time, HOLD YOUR BREATH no warnings, changing gear perfectly even noticed it was engine braking which it didn't do before, 2 miles later still working perfectly .
Just for info the new valves part number aligned with Maxgear part number, although there was no manufacturer name on the box.
Stay Safe.

Congratulations! You saved another C3 from the scrap heap.
I have changed/flushed two AL4 gearboxes a number of times and when filled correctly and then drained, I only got about 2.5 litres out of them. I haven't actually measured the amount but they half filled a 5L container.
If the fluid was grey when you drained it, then it seems they used the correct fluid OR it is the original fluid.
I had the * and S failure on the dash on my first C3. It would occasionally go into "limp mode" (3rd gear), but over all the performance was not good. Strange and clunky shift patterns and not smooth or predictable. The fault in LEXA was not the pressure regulator fault but I cant remember what it was. I changed the modulator valves on spec and that solved my problems. The fluid in the box at the time was DEXRON red. Changing it made no difference so I changed the valves. The biggest pain was all the coolant pipes in the way! I had to feel the position of the selector detent spring when reinstalling it because you cant see what you are doing but you would know that!
I found the gearbox settled down after about 3 tanks of fuel. It seems that in attempting to compensate for the solenoids not working, the ECU buggers up the shift patterns and has to re-learn them. You will find the engine braking when coming to a stop not as dramatic later on.
I only drained and refilled the auto in the second C3. It appeared to have the correct or original fluid and no shifting problems. So I have a couple of spare solenoids that I bought on spec but have not needed to use.

Hi Ozvtr,
Thanks for the reply to my post, unfortunately I'm back to the drawing board
The car worked faultlessly for 1.5 hours then started to play up with gear selection issues or not in my case, box full of neutrals then bang into gear and off with a wheel spin but still no S&S lights.
I'm now working on the theory that perhaps the new valves were ok but perhaps I didn't set the manual spring correctly, when I removed the new valves and put the old one's back I did look for a dark area under where the spring tightens down and lined it up with that. Perhaps misalignment of the spring was causing the S&S light and not the new valves?
I can't find anything on the web to explain how to set it up, so I'm now looking to put the new valves back and align the spring correctly so if anyone on here knows how to do it I'd love to here from them.

Latest update.
Ok I've had some time to think about this, and decided to connect Lexia again and get some live data from the gearbox.
The jerky change issue only manifests when warm which is after about 5 miles of driving with some stop start in traffic and some clear runs so about 20-30 mins.
I decided to warm the car first and get the box up to operating temp of about 60 deg C before taking it for a run to see if the fault materialised quicker.
With lexia attached and in live parameter mode, box at 60c off I went, after 10mins the box started jerking and getting no drive in D unless I went from D to park then back to D. I think this change just encouraged it to select drive which was the safer option rather than revving it up and getting wheel spin when it engaged.
Wouldn't you know it Lexia disconnected half way into the test, but no matter I would reconnect when I got back and read off the parameters.
10 minutes had past till I managed to get Lexia working again but even so the oil temp was upto 80c, much too high as ATF starts to break down at around 79.4c, I left it running and it soon reached 94c.
As suspected oil temp too high causing the oil to break down then intern affecting the gearbox hydraulics.
Well what to do now In anticipation I had already removed the oil heat exchanger for inspection having also read that it contains a filter so was worth looking at.
Being a totally sealed unit not much I could do with it except roughly check the flow, so I poured some paraffin through the square hole which I assume is the feed then turned it up the other way to see if paraffin flowed out of the veins, well it did but took around 4-6 seconds to appear Was this because of the filter? Is the filter that dense that it takes a liquid 4-6 seconds to flow through? or is it blocked? Obviously oil would take longer to flow through.
I don't real know enough about these to make a decision on it's condition especially as they're about £240 quid on Ebay, I did check the water side but that just flowed in and out.
Starting to run out of ideas now so any input would be good.

Did you put the new valves back in? Is all of this on the new valves?
Unfortunately it is possible there is damage to something in the gearbox like a worn brake band. I'm not saying it IS the brake band, just some thing might be broken.
If you haven't, I would put the new valves back in and try again.
I don't think the selector detente spring positioning is critical but I think the manual selector valve piston MUST be inserted correctly.
Unfortunately the gearbox is not giving up much information.
I am not sure the inter-cooler has a filter in it. There is a separate oil filter in the bottom of the gearbox. The inter-cooler would have a lot of channels to disperse the heat, it might take time for oil to travel through them.

Actually, I just re-read your original post. If the car ran perfectly for at least a short while, I wouldn't say there was anything mechanically wrong with the gearbox.
Another "usual suspect" is the pressure transducer on the bottom of the gear box. Could the new modulator valves be putting the transducer under pressure (no pun indented).
I actually bought spares of the valves because they were "Chinese knock-offs" and was not sure of the quality and so I was prepared to replace them on spec if the gearbox continued to fail. But the valves didn't fail.
Is it possible one of the valves is a dud and died after a short period?
Believe it or not I believe the gearbox going into limp mode and displaying the * and S a step up from no indications at all.

Hi Ozvtr,
I did post a reply to your previous post but for some reason it hasn't shown up
I didn't put the new valves back in because didn't have to S&S warning when I 1st drove the car but did after I changed to the new valves so put the old ones back in, warning went away.
Did notice some white sludge when taking the valve cover off but after 6 oil changes no sign of water or sludge, if the box has an internal filter could this be blocked?
some more info from the parameters I read yesterday show evm valve timing around 80-95% put drops to 60-70% when under load (accelerating), the only thing I could see that was incorrect was the temperature.
Pressure around 2.9 - 3.0 bar at tickover and rising to 11 bar underload and always fluctuating so not sure about the pressure sensor but a good call though.
The only way I know how to check the valves is with a 12v supply and they both work with this, is it possible one could go intermittent?
Not sure about that as pressures seem ok, I think.
I will change the valves back to the new ones as I have no other ideas and as you say the readings aren't giving up much info.
I think if the new valves don't work it will be a gearbox removal and inspection to see if any internal damage is causing the high temp, runs absolutely fine when cold.
Off to Cornwall on Monday that will give me plenty of thinking time

If you change from white valves to black valves, the gearbox ECU software needs to know with an update for the timing change with the modified valves.

Hi Arfur,
Thanks for your reply, yes I am aware of the firmware update, the original valves I removed were black BW ones the new valves were also black plug. But I put the old valves back when the new ones gave me th S&S warning.

C3peo wrote: ↑Fri Sep 18, 2020 11:03 am
The only way I know how to check the valves is with a 12v supply and they both work with this, is it possible one could go intermittent?

I checked both the old and new valves on mine by doing the same thing and listen for the clicking. Both sets clicked. So theoretically the old ones "worked"...but they didn't. The valves modulate the pressure by opening and closing very quickly but at varying rates. How this translates into two different faults in your car I don't know. However we do know that changing the valves changes the fault, so there's a clue there. The valves are just coils of wire and a plug that opens and closes. If the wire fused out and went open circuit, that would be that, that's unlikely to go intermittent, it would just stop working. The plug needs to slid backwards and forwards to open and close in a predictable and consistent manor. I can only guess that one of the valves (new set and old set) might stick when hot or not seal against the oil pressure and bleed off pressure?
Ok, so logically you have two trains of thought here. 1) there are two faults, the valves and another. Replacing the valves fixes the valve fault but exposes the other fault. 2) There are two different faults from two different sets of valves. Frankly both of those scenarios are preposterous BUT that's what you have got! So which is the easiest or most likely?
Got another theory?
Just because components are brand new doesn't mean they aren't faulty. This really complicates the fault finding process but it DOES happen!
Yes, there could be sludge or a blockage in the filter but you have to leave that thought 'till last as that involves tearing down the gearbox. In fault finding, start with the easiest or most likely faults first and work towards the hardest faults last.
Yes, according to the internet, it could be anything from the valves to the quality of the oil. But you should pick a potential solution and concentrate on that. When you are certain that is not the fault, move on. Yes you need to think about options but don't let that cloud your fault finding process by thinking too far ahead, you will boil your brain. I am not saying that you are doing that, I'm just saying.
The one shining bit of light is that the gearbox worked fine at least once. That means it has the potential to work fine all of the time.