I have the standard (I.E Cheapest) Clarke press, the 10 ton bench mounted version.

I went to use it last night to press some wheel studs in but something is wrong. When I pump the handle the cylinder moves out as expected but when I move the handle back for the next pump the cylinder moves back with it. This happens with no load so I can even get it to move out to press things.

The press is about 4 years old, has no leaks and has only ever see light use (wheel bearings and studs).

Anyone know what has gone wrong? I assume its some sort of non-return valve that has failed. Can it be fixed?

Cheers

Sounds like the check valve, first thing I would try would be to give it a good wack with a rubber mallet or piece of wood at the pumping section to maybe free something up

these two pages may help

http://www.hyjacks.com/H7.HTM
and an animation
http://www.hyjacks.net/animation.htm

I've had this when the knurled fitting that secures the hose to the hydraulic ram is not fully tightened

David

Cheers, will try whacking it with a mallet to free up the check valve (the 'Clarkson' technique) and also make sure that everything is tight to start with.

Why do these things happen right when you need them most...? probably because if I didn't need it I wouldn't know it was broke.

Always worth checking/topping up the hydraulic fluid, even in the absence of an obvious leak.

Also try holding the piston in whilst you pump (snigger). You may need to prop it up with a lump of wood or a jack of some form.