XSARA - GEAR SLIPS TO NEUTRAL

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

User avatar
CitroJim
A very naughty boy
Posts: 43889
Joined: 30 Apr 2005, 23:33
x 1784

Re: XSARA - GEAR SLIPS TO NEUTRAL

Post by CitroJim »

gfxlearner wrote: Regarding the E2 clutch - can I do something about it , or only a garage can handle it?
It very much depends upon your level of engineering skills and facilities, both of which need to be extensive to work successfully on modern automatic gearboxes..

I have no direct experience of the AL4 but have much experience of rebuilding its big sister, the 4HP20. If you have a look at my website pages on the 4HP20 overhaul, it will give you an idea of the complexity of the job. Please do note that the 4HP20 is significantly different in some critical respects but generally the approach will be similar and will enable you to decide if you might attempt the job.

If you do decide to attempt the job I can offer you a copy of the manuals you will need. Be aware the first job you will have to do is remove the engine and gearbox as a unit from the car..

An alternative, if you decide not to overhaul your faulty gearbox, is to obtain a replacement from a scrapped car but you must source one from an identical car. The AL4 was used in a large variety of cars but all will be different in detail and may not be suitable for your car.
User avatar
Mandrake
Posts: 8438
Joined: 10 Apr 2005, 17:23
x 423

Re: XSARA - GEAR SLIPS TO NEUTRAL

Post by Mandrake »

You need to connect a Lexia to the diagnostic socket and compare the reported "Selected Pressure" and "Oil Pressure" while the gearbox is misbehaving, as demonstrated in the video in this thread:

http://www.frenchcarforum.co.uk/forum/v ... hp?t=49105

Selected Pressure is the hydraulic rail pressure demanded by the ECU for the current gear and driving conditions, and Oil pressure is the actual measured oil pressure. These should track together.

I'll bet you that the Oil Pressure is much lower than the Selected Pressure. If the oil pressure goes below about 1.0 bar the clutches will all let go and you will lose all drive as if you were in neutral.

Unfortunately if this is what is happening, the prognosis is not good. Here is an AL4 with similar symptoms to what you describe that I put my Lexia on a few years ago:

http://www.frenchcarforum.co.uk/forum/v ... =3&t=41417

The car was not repaired and was eventually scrapped. The presumed cause of the problem (no positive diagnosis is possible without a strip down) was a blocked oil filter but it could have been anything that would cause the hydraulic pressure to drop very low under load such as an electrovalve fault.

Reading the gearbox fault codes with the Lexia may also shed some light on the nature of the problem, but its likely that it will just report "Temporary fault, Pressure regulation (difference/setting)" as shown in the video in the first link.
Gibbo2286
Donor 2020
Posts: 5535
Joined: 08 Jun 2011, 18:04
x 1268

Re: XSARA - GEAR SLIPS TO NEUTRAL

Post by Gibbo2286 »

I've not done any of these Citro boxes but in my experience most loss of drive problems on auto boxes are due one of the o rings in the clutches giving out and can often be fixed cheaply if you know how.

What usually happens is the o ring pops letting the pressure drop, the clutch overheats and burns off the lining material and if not stopped quickly burns the steel backing too.
User avatar
Mandrake
Posts: 8438
Joined: 10 Apr 2005, 17:23
x 423

Re: XSARA - GEAR SLIPS TO NEUTRAL

Post by Mandrake »

Gibbo2286 wrote:I've not done any of these Citro boxes but in my experience most loss of drive problems on auto boxes are due one of the o rings in the clutches giving out and can often be fixed cheaply if you know how.

What usually happens is the o ring pops letting the pressure drop, the clutch overheats and burns off the lining material and if not stopped quickly burns the steel backing too.
I presume you mean o-rings on the electrovalves, not o-rings on the clutches ? :-D
User avatar
CitroJim
A very naughty boy
Posts: 43889
Joined: 30 Apr 2005, 23:33
x 1784

Re: XSARA - GEAR SLIPS TO NEUTRAL

Post by CitroJim »

Simon,

That's a great set of useful threads you've found on this problem. I hope it allows the OP to fix the problem :D
Mandrake wrote: I presume you mean o-rings on the electrovalves, not o-rings on the clutches ? :-D
Shades of O ring failure in the Lucas EPIC diesel pump ESOS valves!
Gibbo2286
Donor 2020
Posts: 5535
Joined: 08 Jun 2011, 18:04
x 1268

Re: XSARA - GEAR SLIPS TO NEUTRAL

Post by Gibbo2286 »

Mandrake wrote:
Gibbo2286 wrote:I've not done any of these Citro boxes but in my experience most loss of drive problems on auto boxes are due one of the o rings in the clutches giving out and can often be fixed cheaply if you know how.

What usually happens is the o ring pops letting the pressure drop, the clutch overheats and burns off the lining material and if not stopped quickly burns the steel backing too.
I presume you mean o-rings on the electrovalves, not o-rings on the clutches ? :-D
No I mean o rings on the clutches.