[BrendanP]

My old 2011 diesel has now covered 224,000 miles and it is becoming increasingly difficult to engage the gears without crunching, especially reverse. The clutch has never been replaced, but I do change the gearbox oil at 90,000 mile intervals. I've bled the clutch to no avail. I suspect the clutch is worn out, though it doesn't slip at all. I'd like to check the easy things first, does anyone know what the stroke of the slave cylinder is supposed to be? I could check if it's delivering enough travel on the release lever to dis-engage the clutch.

Just thinking about it, if the clutch plate is worn, shouldn't that make it more likely that the clutch disengages when pressing the pedal down?

It may also be that the gearbox is worn out.

[The Gonz]

Just thinking about it, if the clutch plate is worn, shouldn't that make it more likely that the clutch disengages when pressing the pedal down?

I would think so, Brendan.
Another cause to consider is the - I forget the term - pressure mitigating piston on the front end of the clutch cylinder. Some have removed and hard-plugged it to improve travel.

[Pnut]

Not necessarily. If the friction material is worn then yes there is more clearance, but what often happens is the springs in the pressure plate stretch or break and the clearance becomes less or even the clutch plate warps so rubs and with both cases the clutch is not fully disengaged. This makes it difficult to get into 1st and reverse especially as in those gears the input shaft is at zero RPM compared to the engine. There is also wear differences sometimes on the flywheel and pressure plate if they have had a slip and overhear, causing hard high spots where the rest has worn away.

TBH 224k MILES is legendary, if i got 224k km i would be over the moon let alone miles. Most i have had tend to need replacing around 160k km depending on how they have been treated

[BrendanP]

I'm going to try the fix with removing the damper valve and blanking it off with a sump plug. I don't want to spend much money on the car as the MoT inspection is due in 5 months, and there's always a chance it will fail on emissions. It will then probably be uneconomic to repair.

[The Gonz]

removing the damper valve and blanking it off with a sump plug

THAT'S so much better said than my attempt with a pressure mitigating piston 

[Shambles]

removing the damper valve and blanking it off with a sump plug

THAT'S so much better said than my attempt with a pressure mitigating piston 

Easier to say as well 

[BrendanP]

Update. I've now replaced the damper with a sump plug. This was for a Peugeot 405, requires an 8mm square key which I happened to have. Don't use the washers supplied with it, just the original one already there. Release the valve from the master cylinder by pulling up the spring clip with a small screwdriver. The valve was also a tight fit on the master cylinder, so I had to carefully lever it away using a flat screwdriver. Before starting I unscrewed the bracket holding the fluid reservoir and lowered it until it was at the level of the cylinder, this reducing fluid leaking out.

The gears no longer crunch like they did before. I've ordered the Mitsubishi equivalent to the Hyundai damper and will fit it to replace the plug.

[Pnut]

Nice one!

Whats the purpose of the damper? Do you even need to replace it, just leave it blanked off?

[BrendanP]

UPDATE: I bought the Mitsubishi equivalent for the Hyundai damper and swapped it for the sump plug I previously fitted. The gear crunching returned so had to re-fit the sump plug.

When pressing the clutch pedal, the damper must displace some of the fluid compressed by the master cylinder, which leaves less fluid available to push the piston in the slave cylinder. This reduces the stroke and hence the release bearing doesn't get pushed in as far. In the absence of any leaks, it could be the end of the slave cylinder pushrod and/or the dimple in the release lever have worn which will also result in reduced movement. I'll investigate this another day.

[sundiz]

Seems like the actual clucht pedal can be issue in some models. Might be good to check the pedal also.

[DaveBern]

I had the same issue with mine.  Tried bleeding and removing the damper.  No improvement.  Turned out to be the plastic pushrod from the pedal to the master cylinder was worn.  I made a temporary fix by fashioning up a crescent of plastic and jamming it in between the pedal pin and the pushrod to take up the wear.  That was a year ago and I still haven't gotten around to fixing it properly.  Still works fine.

[BrendanP]

I'll have a look at that - when it stops raining.

Shark Racing have their clutch pedal adjuster for this exact problem Clutch Pedal Adjuster - Shark Racing

If you have access to a lathe and a tap & die set you might be able to make something similar.

[BrendanP]

I finally bit the bullet and had a new clutch fitted, now the gear change is back to normal with no grinding gears. The car is now up to 245,000 miles, but as I know it under-reads mileage by about 3%, the true mileage is more like 252,000.

I posted a video on YouTube for anyone that wants to see what the old clutch looks like.