AL4 gearbox

[The Fixer]

Can anyone help. I have a 1998 406 Peugeot and as I was exiting the expressway I used my gears to slow down when I engaged 2nd gear at 75 kmh the gearbox disengaged and I was freewheeling, after braking to 40 kmh I tried to accelerate around the roundabout, there was no traction and the engine was reving at 3000 rpm.
After exiting the roundabout I pulled over and turned the engine off, waited a few minutes and started the engine and engaged Drive still no traction. I persevered and once I reached 55 kmh the gearbox engaged 3rd gear with normal acceleration at 74 kmh it changed into overdrive still with normal acceleration, I was able to kick-down into 3rd and back to overdrive as normal
At no time did I have Sport/Snow flashing and reverse gear works as normal. I took the car to the local Peugeot workshop and they could not find any fault codes, they advise replacing the gearbox , cost about $ 4,800 + $ 1,000 to install, as the car is valued at $3,000 that option not going to happen.
I Have read in these forums about "the valve block and specifically the Brake Band F3 that engages 1st and 2nd gear via electrovalves controlling the hydraulic pressure to servos and valves.
Can anyone tell me how to replace the electrovalves or how I can obtain the full schematic drawings of the AL4 gearbox.
The Fixer

[CitroJim]

I'd say it was more likely the F3 Brake Band has called it a day rather than the solenoid but only by stripping the 'box can that fact be determined..

I have some information on the AL4, both how it works and how to strip it. Sadly I have no practical experience of doing anything with an AL4 but I do have extensive experience of rebuilding the AL4's big sister the 4HP20.

Both 'boxes are similar and if it's anything like the HP20 then it'll be fairly easy to pull apart and likely much easier than a manual 'box. The HP20 is...

I cannot post the documents I have on here as they are very large PDFs. However if you'd like to PM me your email or email me direct with an address that will accept a 15MB attachment then I can send you them. Else I may have to try to arrange some hosting of them so you can download...

I would bit the bullet and have it out of the car and in bits. Remember they're not as magical as you may have been led to believe and quite amenable to repair.

I'd have the torque converter rebuilt as a matter of course and do the solenoid valves.

Addo, a fellow resident of your neck of the woods, has a Xantia with an AL4 and he has some considerable experience of it. If he doesn't respond here - he may not as he may not read the Pug forum - PM him and ask the question...

[addo]

First actuation test is the dash display!

Second check is the trans ECU, they will only store electronic fault codes.

Mechanical default (all electrovalves off) is reverse, if it was not reversing then it's a control issue or complete lack of fluid pressure.

I'd fit a brand new valve block, which is about $1200 landed presently. Try Midi Auto Lorient. The part number for petrol engined car valve bodies is superseded to 2570.E3 Also make sure the software has been reflashed after 2003 to drive the upper solenoids at 100Hz instead of 50.

The band material is super thin to start with; this can lead to misapprehensions about wear.