Citroen XM Forum

Unfortunately the V6 24v has hit the buffers with autobox failure.
If anyone know the whereabouts of a working 4HP20 off (or on) an XM then please let me know.
It seems that the car didn't like going past 150K, despite having its oil changed!

cheers
Steve

Sorry to hear that Steve, are you getting a grinding noise from the gearbox that worsens with engine speed? finding another unit may be tricky, it will be the same as the Xantia box though i would think, there is an expert on these boxes amongst us here, it may pay to re-build it rather than swap in an unkown quantity but that depends on cost.

D

Exactly, noisy at idle and grinding at revs.
I'm going to ring up the usual suspects. BL Autos, Savoy Garage, Chevronics, etc. Plus an autobox specialist or two.
You never know...

From my experience, best solution is to do a rebuild and I agree with Dean. I had same dilema when I had to do head skimming on my BX, since I had excellent engine in stock waiting to be put in some car - but I decied to rebuild my engine, since now I know what I have in the car.

The stalling was more than likely an early symptom of the failure as the bearing fails it begins to turn the whole bearing in its housing, it will be the torque converter support bearing i think, no personal experience of the issue but i have read reports by others who have repaired such failures, i think it is THE common failure of the box.

D

I would also vote for a rebuild, as the internal damage is probably not too bad, but you won't know until it is dismantled.

A Xantia hHP20 will physically fit, but the ECU will reject it because the gear ratios are different. An ECU swap is made complicated because the Mk1 Xantia ECU won't drive the gear indicator, and the Mk2 Xantia ECU won't talk to the XM diagnostics system.

I will have a good used XM 4HP20 available, about June. It has done about 100,00 miles, so with a filter change it should be fine for another 150,000.

Xantia box though being the same wont work in the XM.. well .. it will but will be in limp mode and will constantly flash the sport and snow lights on the gear selector... not sure for what reason. Possibly incorrect valve block..

I believe Rob's car has a Xantia box, which is the car that originally belonged to Citro Jim, Patrick Rugg and Darren Cross. I think the box was fitted by either Chevonics or BL autos. Regards, Matthew T.

I had a ZF4HP18 box rebuilt on my old Volvo 480 Turbo at JT Automatics in Kent (yes, far away from you, but they were from me too, and I'm pleased I chose them!). They did a great job and the car is still running a 3-4 years later, I'm told.

MTXM wrote:I believe Rob's car has a Xantia box, which is the car that originally belonged to Citro Jim, Patrick Rugg and Darren Cross. I think the box was fitted by either Chevonics or BL autos. Regards, Matthew T.

Which is why we know that the ecu is incompatible. Jim had to modify the wiring and add an extra diagnostics socket to be able to reset the ecu.