Other XC90 Problem: XC90 2.4 D5 2009 Gearbox issue.. BAFFLED! Help :/

[LockStockandKeys]

Good afternoon all. Car is a XC90 2.4 6 Speed Manual on a 2009.

The issue is with the gears. Gradually noticed it was harder and harder to find a gear when driving. Recently lost all gears. I started with the Clutch Master Cylinder. Replaced it, bled it (ton of black brake fluid was between the master and slave). Eventually got gears back. Drove it about for a couple of hours (chuffed with myself). Left it outside post office for 10 minutes. NO GEARS again. Managed to start it while in second gear, it jolted forward of course but got home staying in second.

Bled it at home but no gears whatsoever from that point. I reluctantly listed it for sale needing (in my opinion) a Slave Cylinder. Box off as you know and I am not even 50% confident to do it as a DIY job.

Now, the odd thing is I tinkered with it today, bled the slave cylinder end, but nothing changed. Still no gears. I really needed to move it so cranked it while in gear and this time, it lurched forward but then idled. Went straight into gear and now I have ALL gears back again.

I am seriously baffled now and I refuse to let this beast go cheaply if I am missing something stupid.

Before the last start up, I removed the clutch pedal switch, and I remember before that it did manage to go into gear after removing it previously.

So..... my main question is this: If the Clutch Slave Cylinder has failed, would it be able to somehow get itself back working temporarily?? Or would it be a total fail? I have not lost any brake fluid since last flush and top up.

Also, is this daft little clutch switch tricking the car that the pedal is still upright and refusing to let the box change gear?

Or else can anyone shed any light whatsoever in my direction please?

Your help (even as small as it might seem) is TOTALLY appreciated.

Thank you

[Tannaton]

The manual gearbox does not have any electronics to operate it or control it, bar a speed sensor and reverse sensor.

Sounds like you have have an issue with the automatic clutch plate adjustment. I would say I think it's clear your issue is the clutch rather than the gearbox.

But the gearbox still has to come out to get to the clutch... pity not all car manufacturers that the insight that Vauxhall (Opel) did.....

Cut and paste from a BMW forum

SACs have a few basic failure modes:

1) Incomplete disengagement - you can never fully release the clutch. Symptoms include difficulty getting into or out of gear. Cause: Over-adjusted pressure plate. Final result: clutch failure from excessive wear, potential transmission synchro damage from forcing gear changes.

2) Incomplete engagement - clutch does not hold as strongly as it should due to insufficient clamp load. Symptoms include slipping, especially in high load/low-rpm situations, burning clutch smell. Cause: Under-adjusted pressure plate. Final result: clutch failure from excessive wear.

3) Inconsistent engagement/disengagement - sometimes engagement point is higher, sometimes lower (different than changing slave hydraulic fluid temp!). Cause: combinaton of #1 and #2 above, but adjuster sliders slipping back and forth. Final result: clutch failure from excessive wear, potential transmission synchro damage from forcing gear changes.

4) Juddering engagement - impossible to engage cutch smoothly, particularly in First or Revers. Cause: one or two of the three adjusters may be stuck. Final result: clutch failure from excessive wear, potential transmission synchro damage from forcing gear changes.

What causes these problems with the SAC mechanism? The mechanism gets fouled by normal clutch dust and the spring-loaded adjuster sliders get stuck either permanently or intermittently. Also, a "clutch dump" hard launch can knock the adjusters into a different position where they may get stuck.

[LockStockandKeys]

Originally Posted by Tannaton

The manual gearbox does not have any electronics to operate it or control it, bar a speed sensor and reverse sensor.

Sounds like you have have an issue with the automatic clutch plate adjustment. I would say I think it's clear your issue is the clutch rather than the gearbox.

But the gearbox still has to come out to get to the clutch... pity not all car manufacturers that the insight that Vauxhall (Opel) did.....

Cut and paste from a BMW forum

SACs have a few basic failure modes:

1) Incomplete disengagement - you can never fully release the clutch. Symptoms include difficulty getting into or out of gear. Cause: Over-adjusted pressure plate. Final result: clutch failure from excessive wear, potential transmission synchro damage from forcing gear changes.

2) Incomplete engagement - clutch does not hold as strongly as it should due to insufficient clamp load. Symptoms include slipping, especially in high load/low-rpm situations, burning clutch smell. Cause: Under-adjusted pressure plate. Final result: clutch failure from excessive wear.

3) Inconsistent engagement/disengagement - sometimes engagement point is higher, sometimes lower (different than changing slave hydraulic fluid temp!). Cause: combinaton of #1 and #2 above, but adjuster sliders slipping back and forth. Final result: clutch failure from excessive wear, potential transmission synchro damage from forcing gear changes.

4) Juddering engagement - impossible to engage cutch smoothly, particularly in First or Revers. Cause: one or two of the three adjusters may be stuck. Final result: clutch failure from excessive wear, potential transmission synchro damage from forcing gear changes.

What causes these problems with the SAC mechanism? The mechanism gets fouled by normal clutch dust and the spring-loaded adjuster sliders get stuck either permanently or intermittently. Also, a "clutch dump" hard launch can knock the adjusters into a different position where they may get stuck.

This makes sense to me. Thank you. I got a labour quote for £300 (private mechanic). Parts (Clutch, Flywheel, Slave) £575. So Total £875.

Second quote £1600 all in, which I thought was a joke personally. I know it's a big job but for a transmission specialist I would expect a realistic figure.

Thank you for your opinion and I believe I will keep the car for sale as needing clutch for peace of mind.