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MG Midget and Sprite Technical - Leaking Trolley Jack

A chap has kindly (or so I thought) given me a trolley jack. But it slowly subsides over a few hours.

Many of you will know that I don't have the instincts of an engineer, so can you tell me how I get into the thing? I'm kind of afraid to start, in case little bits fly out in all directions.

Nick and Cherry Scoop

Before you tear into it here are a couple of things to try.
1: Check to make sure it has enough oil in it, use a quality hydraulic jack oil to top up as needed.
2: Place it in a vise, holding it close to the end of the ram, with the end of the ram pointing down (wrap it with a rag so you don't damaged the surface). Pump the handle to extend it all the way, apply pressure & open the valve. Try this a few times to see if it is just air that can be bled out.
3: Unscrew the valve & inspect for damage. It may just be dirty & need a little cleaning.
4: If these fail to resolve the issue, drain the cylinder completely and give it a fresh fill of oil. Bleed as needed to clear all air out of the system.

I would do all of those before tearing it apart & hoping to be able to purchase all the seals, O-rings, etc. Many times it's cheaper to just buy a new cylinder than to waste the time on an old one.
s1

Now, there you go, you see - treating me like a competent person.

Where is the valve? How do you open it? What sort of oil? How do you bleed it?

I forget - who is s1? What spanner do I need to undo these aliases? Or is it an Allen key?
Nick and Cherry Scoop

Nick,

My trolley jack has done that almost from new but it doesn't bother me as the jack shouldn't be used to hold something up that long, axle stands or blocks get placed as appropriate to perform any long term support. My engine crane droops over time as well but that's only if the release screw is nipped up, if tightened a bit more it stays in place. Maybe one day I'll pull the screw and check the seat and seal and see what I find.
David Billington

The valve is the little thing you turn to lower the jack or close it so you can pump it up. You open & close it by turning one way & the other. Hydraulic jack oil, should be able to purchase at an auto parts store or industrial supplier. Bleeding, mount like I stated earlier, close the valve, pump the handle so it extends, apply pressure trying to compress the cylinder, open the valve & compress the cylinder until collapsed, close the valve, repeat 5 to 10 times. There is probably a set screw looking item on one end or the other of the cylinder (perhaps the red item just under the handle pocket in the photo but that's a guess). Can you provide a picture from the left hand side in the picture?

I'm Stanley Kowznofski, I can't figure out how to have it show that when I post.
s1

there are plenty of youtube videos showing how to fill with oil did mine a few years back
mark heyworth

Nick - what David said. They nearly all do that as oil is gradually pushed past the piston seal under load.

Stanley - you should be able to mend your screen name if you click (or tap, depending) on the "Customise" button on the right at the top of this page.

HTH
Greybeard

The valve usually consists of a ball bearing that sits in the bottom of the hole where the valve screw goes. It may help to remove and clean the ball, and check there aren't any wear ridges on it if it may have been overtightened.

Who else cannot read the thread title without​ thinking of Victoria Wood? Is it on the trolley?
GuyW

Some also have a tapered seat & needle and get damaged from over tightening as well. With cylinders that lay on their sides, when they have some air inside, the air will ease by the piston seal (as Graybeard eluded to) causing the creep / settling.

To Graybeard: Thanks for the tip on customizing.
Stan Kowznofski

Nick,
if you know the make and model you might find there's a instruction and parts leaflet for it.

The principles will be the same so here's a link to a Halfords trolley jack 'Instruction Manual' (leaflet) as it has a troubleshooting list and how to add and replace oil.

http://www.halfords.com/wcsstore/HalfordsConsumerDirect/images/catalog/Halfords2TJackShortWheelBase(332236)-Manual.pdf

You've already gone further than I would by taking it apart as you have. I found just doing an oil change go my other jack working again, bottle of jack fluid could have done the job twice or for two jacks and wasn't much cost.

£4.99 now for a 500ml bottle of Halfords hydraulic-jack-oil.
Nigel Atkins

Thank you very much. I think I can do these things now.

What is the screw with the plastic cap saying 'do not adjust'? It's almost an invitation, isn't it?

I do agree with David. I never go under the car with just a hostess to look after my well-being. But my other jack (Machine Mart) that I've had for years is rock solid.

Do you think Armstrong damper oil might do it? I've got loads of that.
Nick and Cherry Scoop

Nick,

The screw with the plastic cap saying 'do not adjust' is almost certainly the safety valve that prevents you overloading the jack. IIRC it's an EU requirement that all lifting stuff like engine cranes at least have such an item and are proof tested.

David Billington

Damper oil probably fine. Last time I filled one I think I used some redundant gear oil.

The "do not adjust" will be a pressure relief. Essentially an anti-overload device. Unlikely to be an issue with a Spridgets weight, but theoretically could be what is bypassing and letting it sink. Probably not. Most likely the valve Guy mentioned or a worn piston seal.

Personally if it holds the car up long enough to get the stands in place I'd probably settle for that, until it got worse. It owes you nothing after all.

Mine is not too old, but if I jack the car up and put the stands under the axle it will gently lower the car onto the stands in about 10 minutes or so.

Edit: slow typing. Crossed with David :-)
Greybeard

I think, don't know, jack fluid is thinner. Not tracked down a certain answer in time available but it might be around 10 SAE but they vary.

There, clear as mud from me.

ETA: just seen others say its fine so that allows for the variances in SAE then. :)
Nigel Atkins

I'm sure you're right Nigel. It was pretty rough of me, but I just chucked in whatever was handy. AFAIK it still works and it was a big bugger in a tractor workshop.

It's bank holiday weekend, mate. You need to go to the pub haha!

Edit: I just remembered it was Hytrans oil. Used as combined hydraulics and transmission oil in Case tractors. No idea of the viscosity.
Greybeard

You can buy a bottle of Hydraulic Jack Oil in Halfrauds.

I have three trolley jacks. One is a Halfrauds own brand and it is rubbish. It started leaking after only a couple of years light use and has been discarded. Another is a 45 year old Draper that still works brilliantly but leaks oil big time all the time. Draper are unable to supply new seals for such an old model.

The last is a large, low entry, Sealey model. This works well except that it very slowly descends when the car's weight is on it. It can take hours to go right down, but will go down eventually, and it's done this from new. Also the release mechanism is too stiff and it's very easy to drop the car suddenly, not a problem if you are landing on the wheels, but not what's needed if you are putting it on stands. I took it to a local Sealey agent while it was still in guarantee and they rebuilt it, but it was still the same. The engineer said he wasn't surprised at the way it performed. In his opinion the design was rubbish!
Mike Howlett

Well, this thread has taught me something. My 20-year old Machine Mart jack doesn't drop at all, overnight for example, and I thought that was normal! Perhaps I should leave well alone with my second one, which is admittedly a luxury. I will just have a look at the ball bearing, but perhaps then I'll just put it back together.
Nick and Cherry Scoop

By the way, I forgot to say thanks very much, Stan. I will do what you suggest, and then put it back together and be happy with a sinking jack.
Nick and Cherry Scoop

I have a Machine Mart 2Ton bottle jack which must be 40+ years old which doesn't lose pressure at all, even if left loaded for several days; it remains rock solid. As far as I can tell the design is almost identical to these trolley jack rams, with just a different shape to the base of the casting. I don't understand why it should be acceptable for a trolley jack to slowly loose pressure like this.

My market-stall sourced trolley jack was subsiding like that last year. I stripped it down and found that the small piston cup neoprene/rubber seal was split. Some may recall I posted on here about sourcing a replacement for the seal. In the end I repaired the seal with a moldable rubber product called Sugru. A bit unsure of it at the time, it is still working fine and the trolley jack is like a Dyson, it doesn't loose pressure.
GuyW

I do wish I were blessed with more common sense. I've just unscrewed the valve, but when I pulled it out I happened to be leaning on the body, with the extended piston resting on the bench. A ball, a short (3/4") piston and several ccs of fluid shot out, all hitting me on the chin.

So I've worked out that fluid goes in first, and presumably the piston next - though I didn't see in what order they hit me - but where should the big piston be while I pour in fluid?

Glad I started this.
Nick and Cherry Scoop

OMG, Guy. Just read your post again. I did not notice a cup bouncing off me!
Nick and Cherry Scoop

Hi Grey,
I wasn't having a go at you, that would require organisation which at the time at least I didn't have, I was typing my post while you posted yours and I was rushing . . .

because my wife wanted taking to a pub!

She had Gwynt Y Ddraig, Happy Daze draught cider and I had a very excellent cask Purity, Pure Gold. We spoke with the landlady's husband who we know about him wanting to sell a BGT, his Mini grass racers and other stuff, a pleasant distraction from getting messy replacing rubber parts on my Midget on a hot day.
Nigel Atkins

Nick, the cup shaped piston seal that l repaired was part of the actuating piston - the bit that pumps up and down as you use the jack.
It sounds like you unscrewed the release valve which contains a ball bearing and maybe a spring, but no piston seal.

When l refilled mine l removed the rubber bung in the body of the jack and used a syringe and short length of windscreen washer tube to inject it in. The filler backs up quite quickly and you then work the jack up and down slowly to allow the air to escape before topping it up further.

An improvement to make on some is to remake the two pivots on the pump handle arrangement as they are usually very slack. Be careful when you remove that piston though as it is likely to spew oil out all over the floor, if not over you!
GuyW

This is what came out, Guy. Ball and spacer (not piston). It looks from the wear as if the spacer gets turned and ground by the threaded release screw, and it turns and wears against the ball. The spacer must be a lot softer than the ball.

I did not realise that the shallow dome on top of the cylinder, painted body colour, is a rubber bung. That explains it. BTW, while filling, what should the status of the release valve be? In, out, shake it all about? Anyway, thank you. I feel I'm nearly there, though I wish I hadn't started this little job.

PS:- I was joking about being hit by a cup.

Nick and Cherry Scoop

I like the artistic presentation of that photo Nick. Very "Art Nouveau"
GuyW

I would just bin it!
Eddie Cairns

Eddie, I am SHOCKED!

Merci, Guy du Lac.
Nick and Cherry Scoop

These may be of use to you Nick.

http://youtu.be/qjQKl1K3ZUg

http://youtu.be/pAyOKYG-R_s





simon (1275 mk4 sprite)

29 minute videos! Who has the time to watch these long winded and poorly put together videos? There are several much shorter 3 and 4 minute explanations available on how to fill and bleed a jack
GuyW

Why not just buy a new one - if you have Costco nearby, I'd recommend the one I bought.
http://www.costco.co.uk/view/p/arcan-2000kg-aluminiumsteel-service-jack-model-hj2000eu-900930

It sits nice and low, but too big to go in the boot!

Graham
Graham V

I've already got another one, Graham. I don't know why I started messing with this one really.

That Costco jack does look good. 10.2cm is pretty low. But I can hardly believe the width of 30cm! A lot of the time I find myself manoeuvring the jack tight alongside an axle stand, and this one wouldn't get near, unless maybe you take the carrying handles off.
Nick and Cherry Scoop

I've just checked mine and 30cm is indeed the correct width of the rear (right hand side of picture) arms supporting the rear wheels.
The external front wheels width measures 25cm.

Graham
Graham V

Before you get into this...go to your machine mart... these little pumps are cheap

We have them at harbor freight..
.

The one thing about buying a new replacment is safety... esp for a jack,,that is somethimg i take very seriously, i want to always have total trust in my jacks

For what these things cost... ots not worth it to be screwing around with my life o the line

Prop
1 Paper

But you shouldn't get underneath a car only supported by a jack anyway so, as long as the jack raises the car, it's done its job.

Bill
W Bretherton

Now that our vizzies have gone home, I was able to test my fully oiled-up jack (syringe method - thank you Guy, and thank you Laura for GIVING me the syringe that was languishing in a drawer in the kitchen).

I lifted the back end of the frog 3/4" off the axle stands, and heard it settle onto them again half an hour later.

Could be worse. I think I'll leave it alone.
Nick and Cherry Scoop

This thread was discussed between 28/05/2017 and 05/06/2017

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