Citroen XM Forum

Just a brief update to confirm that the engine box are now reunited and back in the car and securely attached! I did also take the opportunity beforehand to 'hot wire' the starter and turn over the engine (after disconnecting water and hydraulic pump belts) and to my great relief all sounded fine! I shall now slowly complete the refitting beginning with the essentials and then carry out a further 'test run' before attaching the drive shafts and exhaust etc. With regards, Matthew T.

Nice to see it's all back in one piece.

Many thanks Will that is kind and we are slowly getting there! I wonder how is your project going? With regards, Matthew T.

Good effort Matthew, glad to see you have it all coming together nicely!

D

Thank you Dean and I should have really had it back together before now! With regards, Matthew T.

Hi All,
I know have the car up and running again, but rather distressingly the gearbox is still not right. Here is a brief summary of the issues:
- As before, there are definitely missing gears and although I seemed initially to have first, that then quickly disappeared.
- It is possible to manually select first gear, but in Drive the car definitely pulls away in second gear.
- There did initially seem to be two changes, which I assume were 1-2 and 2-3, although fourth gear has certainly never materialised.
- The 2-3 (only) change is also quite reluctant and not especially smooth and sometimes does not seem to happen at all.
I am very much hoping that the valve block is the problem, as had been advised before, but then again it has now been looked at twice.
At this stage I have sent a text to my gearbox specialist based on the above and suggested removing and delivering the valve block for further checks. I also have a spare known good block that could be tried and the good news is that the gears are not yet slipping as yet.
I hope these thoughts are helpful and assist any initial thoughts on the matter and advice to be offered by those in the know.
With many thanks,
Matthew T.

I wouldn't count myself as being in the know but would fear the root cause has still been left unresolved and further use could destroy the clutch packs again, the odd and slurred changes could be two gear selections trying to be made at the same time, i dont know, but if line pressure is good and there is no fault with the clutch packs themselves then i would be looking very closely at the valve block personally.

So far as i know clutch packs do not just burn out, something makes them do it, low line pressure or faulty valve block components.

D

Many thanks for those helpful thoughts Dean and what might cause the low line pressure? There was previously an issue with damage to the pump, which the specialist then changed, so could it be the pump? With regards, Matthew T.

Again, I'm not a specialist, not close, but some shifts require a lot more pressure to operate and i think a shift to reverse requires the most by a substantial margin, so if you were losing hydraulic pressure it would either be something leaking it away or the pump not making the pressure in the first place, BUT you would end up with a box that would not shift into reverse first if it was a small drop in pressure, if it was a massive loss in pressure then you would get slipping clutches and with no pressure, you would not be able to engage the clutches and would have no drive at all.

If you get drive selection at idle and reverse in idle and the car creeps in both directions at idle then i would say pressure is fine (the test ports are easily accessible with the box in the car for diagnostic purposes) but if it then won't shift correctly the brain isn't telling the clutches what to do (valve block fubar'd) or the brain isnt being fed the right info although in this case there is nothing you could do to the shifter or kick down cable that would cause this, i doubt very much the governor could, however, i wonder if the torque converter could fail in such a way as to cause these issues.........not sure

Do you know why the pump failed in the first place? oil pumps never just (well, very rarely)......fail. Did the drive teeth shear off the torque converter, did the torque converter bushing fail and load the pump? did the pump ingest something it shouldn't have? in which case the pump would not be the issue, it would be the effect. Also, did they tell you what the problem was last time it went back?

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Thanks again Dean and that is reassuring advice about the line pressure. There certainly is a strong take up on Drive and reverse gears from stationary and it does seem to be more of a gear selection/ changing issue. In response to your queries, I understand that the original problem before I had the car was a failure of the torque converter that may be damaged the pump, which I understand from my mechanic was a bit scored. The most recent issue I was told had been with the valve block and I think simply a stuck valve, but I am now beginning to wonder! With regards, Matthew T.