Technical I no longer trust my Multipla

[technomage]

I have a Fiat Multipla ELX JTD (03 reg – 99,000 miles) which I no longer trust. Perhaps you can restore my faith..?
I think it’s the clutch, but before committing to a replacement (expensive) I wanted to get a second (or more) opinion.
I have no trouble with short journeys or even some long journeys, the fault seems to present itself under specific circumstances – for example:
I traveled from mid Wales down to the M4 (no problems) carried on down the M4, crossed to the M3 then round the M25 (still no Problems). Then I left the M25 to head into London and after a couple of miles I couldn’t change gear..! No matter how hard I tried, it was impossible to select any gear (very disconcerting stuck in the middle of flowing traffic..!) I had to get out and push the car over to the side of the road and wait…
After some time (hour or so), I jumped back in, started her up – and no problem..! I left the car parked up for a few days (for me to worry about the return journey..!)
Returning to mid Wales I took a different route back, still round the M25, via the M3 and M4 but dropping off at Swindon and the rest of the journey was via (mainly) A roads - no problems..! I got home worried (but relieved).
The same happened on a trip to Birmingham – A roads, motorway, couple of miles off the motorway – no gear change..! Leave the car (get the bus), return to car, drive back to mid Wales without problem.
The other day as an experiment (and out of curiosity) I tried changing gear without the clutch depressed – very similar to the problem I have after traveling some distance via a motorway.
I have taken it to a couple of different garages, neither could find a problem (but one did change the gearbox oil).
So – should I just have the clutch replaced and hope that cures the problem..?
Thanks..!

 

[widemouthfrog]

Have you tried bleeding the clutch hydraulics?

Oh - and welcome to the forum!

 

[doody]

as said above try bleeding it. what's the colour of the brake fluid as it should really be replaced every two or three years?

if that don't work it will be your slave cylinder that will need replacing as the standard one fitted by fiat is crap and has a plastic rod which bends when it gets old.

 

[BikeDoc]

When it's 'impossible to select any gear', is that because the clutch won't disengage?
When it happens, and you stop the engine, can you select a gear/gears (without the Clutch)?

I doubt very much if it's a problem with the Clutch itself, but the Hydraulics that actuate it.
As WMF and doody suggest, I'd get the Clutch system bled, flushing out all the old fluid.
Hydraulic Fluid is 'Hygroscopic', it absorbs moisture from the Atmosphere.
Dust and dirt can also get into the Fluid.

If it were me, I'd also remove, strip, clean and check the Slave cylinder.

 

[disgusted]

Deffo clutch hydraulics. Probably slave cylinder. Reasonably cheap job...