I have noticed a few times over the last few months that at odd times the clutch appears to be slipping.  Last time was yesterday going to work.  on leavening 2 roundabouts the revs went up but indicated speed didn't.   Being a paranoid person i immediately thought the clutch was on the way out and set about testing it.  on driving up a steep hill i slowed to about 40 in 5th and then floored the throttle.  it all worked as expected ie revs climbed steadily with an increase in speed.

All this is to say i think i have a hydraulic issue and wanted to see if the operating mech was working properly however, i cant seem to see it so is it internal??  Has anyone else had a similar issue?

 

on doing some back ground reading i came across its supposed to have a "clutch position sensor" what is this?  is it anything to do with this issue?

 

many thanks

Coop

The slave cylinder is inside the gearbox, you can't see it from outside.  You can check to see if there's any clutch fluid leaking from the join between the engine and gearbox.  If you've got an undertray, that would need to be removed first.  You can also check the see if the pedal is sticking down when it slips - ie, can you lift it back up slightly with your foot underneath?

The clutch switch is mounted by the pedal, it just tests whether the pedal is up or down - allows the PCM to make smoother gearchanges (rev matches against speed) and is a safety cut-off for cruise control where fitted.  It can't cause the clutch to slip.

Sometimes clutches do slip momentarily if you let them in at high revs but they'll be fine again afterwards.  You can't always force a clutch to slip in a high gear uphill either, there is no sure-fire test for a partly worn clutch so I'd suggest yours is probably just starting to get towards the end of it's life now.  I'd just keep an eye on it for the next few drives and see if it happens again.

I had a similar problem.

250 miles into a journey the clutch started to slip on high engine outputs, all OK if taking it easy.

Came off the ferry and all was fine until the engine was fully warm again, then the slipping returned.

Took it easy for a day or two till I sorted out a local garage who did a full clutch change and slave cylinder, £300 odd if I remember correctly.

On collecting the car I inspected the scrap bits to find that the clutch plate was still serviceable, no oil and a decent amount of friction material left. The only conclusion to me was that the diaphragm spring had weakened causing the slippage when the spring itself was hot. The original parts were as built.

That was 3 or 4 years ago and I can report that it's still working fine.

Hope this helps,

ScaniaPBman.

about 30 years ago a friend had a Fiat 126 and clutch slipped like mad. I replaced clutch for them (quite easy on Fiat 126 , removed rear bumper, remove the cross member behind rear bumper, undo some bolts and stuff and can pull the gearbox and engine out together on a trolley jack). anyway , tons of friction material left , but the diaphragm spring just seemed to have lost it's strength, no broken bits on it, just not strong enough.

When i have had cars where the clutch was worn and slipping (had a few in my 40 years of driving) they have been worse when hot (engine, not weather). 

When doing the test to try to force clutch slip, I also apply the footbrake a bit .