My engine crane has started creeping very slowly down when loaded with an engine (something like a few mm per minute at the piston). I've had it from new for a few years, it didn't do this when it was new.

How safe is it to use... is there any risk that it will suddenly get worse while I'm hoisting the engine out, and drop the engine?

And how could I fix it? Are these things serviceable?

Assuming you are not loosing oil then I suspect the control valve could be the culprit... cheapy ones tend to leak though if they have been over-tightened.

A few mm a min is not a huge amount.... you should only be using the crane to lift the engine, not hold it up to work on it. Safe enough provided you take the usual caution and dont put any bodyparts you value between the engine and the floor!

[Edited on 29/7/12 by tegwin]

Seals going in the piston. I've got a jack like it (not as bad as yours), i wont get under the car on just the jack.

What make is it? It could suddenly go, or it could be like that for years.

Sounds like a leaking seal? Don't take any chances with it , if you can't get a seal kit try CFE Hydraulics in Milton but take the old ones as pattern

It's a cheap(ish) chinese crane I got from Ebay - it looks exactly like the Clarke one.

Anyway it's not urgent (I'd like to do the clutch but can put it off for a bit) so sounds like I'd better sort it out before using it. Annoying but can't risk it letting go at the wrong moment.

Sounds like air in it. My hoist did the same try topping it up and bleeding it. Slacken the release screw and pump it a dozen or so times then tighten it back up and try it. If it still does it repeat the procedure.

[Edited on 29/7/12 by Peteff]