Hi I have a great wall x240 petrol manual. All of a sudden it has started over revving when clutch is pushed in when changing gears..any idea

this vehicle is unknown in North America where we are. One video.

https://www.google.com/search?q=Great+Wall+X240.+How+to+change+a+headlight

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The clutch is not transferring power to the gearbox, which then is not turning, so that you can select gears without the clutch.Possibilities are
- clutch assembly has failed, possibly by the splined driven plate hub coming adrift
- clutch driven plate has become very worn and has lost contact
- slave cylinder has stuck through corrosion (assuming a hydraulic clutch) and is holding out the clutch independent of the pedal. This can be determined by watching it while someone depresses and raises the pedal.

I think it is unlikely the transmission input shaft has fractured.

Eric, how are you confirming whether or not the car goes into gear if you shift gears without the engine running? One way would be to put it in 1st and see if you can push the car. If you can't, it is in gear.

Another option is to roll the car slightly forward or backward (engine off) while trying to put the car in gear. Once it is in gear, then the car shouldn't move any further. However, if it goes into gear, DO NOT start the car without taking it back out of gear.

The clutch is much more likely to be the problem than the transmission.

If the clutch fluid ever ran dry, then the clutch hydraulics will need to be bled of air. Otherwise, the problem could be the clutch master cylinder, slave cylinder or throwout bearing. Since you didn't report the clutch slipping (e.g. engine revving without accelerating when in gear) it is likely not the clutch disks themselves.

How long since you had the FUEL FILTER changed?? Because it sounds like Fuel starvation, and if it is an old Filter..... then that is PROBABLY the Culprit

great wall x240?
this
The Great Wall Haval H3 (Chinese: ; pinyin: Changcheng Hafu), also known as the Great Wall Hover, is a compact sports utility vehicle (SUV) produced by the Chinese manufacturer Great Wall Motors since 2005.

unscrew lamp , replace. if it has Euro style lamps.
easy huh?

thrust bearings are bad and the flywheel is moving out of range of the crankshaft sensor, or the crankshaft sensor is sitting too close to the flywheel.

Check the slave cylinder is coming out when you push the clutch down ,without my head under the bonnet its difficult to say but either you have lost the fluid or the thrust bearing has now pushed through the pressure plate with the correct pressure .

One of three things 1) All the hydraulic fluid was suddenly lost from your clutch - check the fluid reservoir level under the hood on the fire wall bulk head 2) the clutch lever or release bearing has broken 3) the clutch diaphragm spring on the clutch plate has broken These last two can be checked by waggling the end of the clutch lever but any repair requires the transmission to be removed. Might be a good time to change the clutch and bearing while you are it.

adjust clutch. check clutch pads, release bearing, pressure plate.

1st gear syncromesh Is worn or broken. This usually is caused by forcing lever in when clutch is not disengaging fully, or changing gear with out disengaging clutch.
MMP