Problem with a car jack

[Andrew TinsleyParticipant @andrewtinsley63637]

I have a DUCO car jack which is of generic Chinese origin. When the handle is pressed down, the jack rises, but when the handle is raised for the next stroke, the jack goes down!

Obviously there is a non return valve which is either stuck or simply not working. I stripped down the jack, expecting to find the non return valve without too much trouble. However I simply cannot see anything resembling a non return valve!

The jack is getting on in years, but has had minimal use. My curiosity has been aroused and although I would like to fix the problem, I am more than intrigued by where the non return valve is hiding.

Regards,

Andrew.

[renardiere7Participant @renardiere7]

Trolley or bottle?

[Robert Atkinson 2Participant @robertatkinson2]

This manual gives some good trouble shooting advice before you tear it apart.
https://www.mackay.co.uk/media/manuals/draper/39054ins.pdf

Robert.

[noel shelleyParticipant @noelshelley55608]

It may a gravity held ball – all to easy to loose on dismantling or not even see. A few sharp blows with a hammer on substantial bit may cause it to seat, OR it may have an overload valve that has failed. IF the oil is far to thick it may not operate, should be SAE 10 = hydraulic oil. Noel.

[Andrew TinsleyParticipant @andrewtinsley63637]

Should have said trolley jack. I dismantled it once and could not find the one way valve, So I reassembled it and filled it with fresh SAE10 hydraulic oil. Not surprisingly it did exactly the same thing. So i dismantled it again and now looking for inspiration.

Andrew.

[martin haysomParticipant @martinhaysom48469]

i had this with one of mine stripped and cleaned it could find nothing wrong. rebuilt it some times it worked sometimes it didn’t work. went through the whole process again, same result, binned it and bought a new one before someone got hurt [me that is]

[Eric OlthwaiteParticipant @ericolthwaite]

If it is one of the standard Chinese trolley jacks, of which there are many exploded parts diagrams online, there is a spring and ball in a hole in the main valve body. You remove the blanking screw from the hole to access the ball and spring.

If cleaning out the hole and seat etc does not cure the problem, sometimes the ball can be reseated by putting it in place on the seat and tapping it sharply with a hammer and brass drift.

Otherwise you might need to recut the seat with a suitable cutter, depending if it is a flat or cupped seat. A ball bearing silver soldered to a piece of rod can make a lapping tool to use with fine grinding paste also.

Also check that the ball has no blemishes from corrosion and replace it if not perfect. A powerful glass is needed for inspection as any tiny blemish will leak.

I have a collection of trolley jacks, dating back as far as WW2, and they are quite interesting pieces of equipment if you sit down and study them. Their restoration can provide many hours of challenging but pleasureable work  .

[duncan webster 1Participant @duncanwebster1]

I suspect not the problem here, but I have a jack which sometimes lets down of its own free will. I suspect the O ring on the piston has shrunk, but as I don’t do car maintaining any more I haven’t got round to investigating. It’s not obvious how it comes apart. Too good to chuck, but I suspect whoever clears out the shed after I’m gone will do so

[Ches Green UKParticipant @chesgreenuk]

Andrew,

Mustie1 repairs a faulty floor jack here…  https://www.youtube.com/watch?v=UtnraagSEXA 

It has two pistons, one quick-rise/low pressure and the other slow rise/high pressure.

There was at least one part missing from his yard sale buy, but I think the problem(s) were to do with dirt in the system and low oil.  And maybe someone had tried to ‘repair’ it before him.

Ches

 

[noel shelleyParticipant @noelshelley55608]

The valve in these things are balls, I have seen some ball races where the balls are just round lumps of mild steel. If this type of ball is used it will soon fail – remove and replace with a stainless one but buy at least 2 – use one to tap down to form the seat and the other to fit DO NOT mix them up. Another thing that fails is the little clip that attaches the handle to the pump ram on small ones, a bit of hammering and forming of a bit of thin strip will do – or try to buy a new one. The screw down release valve may be a simple one or may have a ball under the screw check this ball or replace. Noel.

[Andrew TinsleyParticipant @andrewtinsley63637]

Plenty of good advice there. Looks as though I will be doing some checking out over the weekend! Thought there may be someone recommending to bin it for safety reasons. Anyone who relies solely on a jack wants their heads examining. Hence no reason to bin!

Thanks everyone.

Andrew.

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