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MG MG Y Type - Jackall Seals

Guys,

I know this subject has come up time and again in the archives and I've spent all morning looking through those. I have also purchased the Jackall info sheet from the register along with their reproduction of the Jackall service manual and yet I still can't find the sort of "idiots guide" information that I'm looking for.

My jackall system has the typical problem of just lacking the oomph to get the car off the ground. There are no obvious external leaks so I'm guessing that something within the pump itself needs sorting.

So I purchased the set of pump seals available from the register. The only problem is that I can't find where they need to go.

I've taken the pump off the car, and taken it apart (as much as I seem to be able to easily do) but am still none the wiser.

I've taken the front plate off which gives me access to the emergency pressure release thing - I took off the tiny leaf springs and I turned them around for luck.
I can take out the two filters in the bottom for the front and rear "circuits" and cleaned them up.
I took out the release knob, the two nuts underneath, the front/rear selection cam, the big spring, the little metal retainer and the bit underneath that the release knob runs through.

Then I ground to a halt. How do I dissmantle the rest of it, and more specifically where do these three little green rubber seals go?

Please help.

Cheers,
Saul.

Saul

You might find that by simply cleaning out the pump, its line from the reserviour, and the insides of the reserviour, you might improve the pump 100%. The seals do not fit onto and sort of piston, they simply sit in the pump under the cap. Those in there at present will be rock-hard and hard to identify as seals, look for a hole about the same size as your new green seals. The seals 'seal' the shafts of the various rods inside, so where you pull out a control rod, there will be a seal around it.

Neil.
Neil Cairns

Jack Murray kindly responded directly to me with the following:

Hi Saul,

I've just read your note on the bulletin board but unfortunately am unable to add to your thread. (Goodness knows why!)

Anyway, I've never actually taken my pump to bits as it currently works fine.

However, many moons ago I copied an exploded diagram of the pump from an old magazine. I think it shows an earlier type than is fitted to our cars but I feel sure that the principal and internal workings are much the same.

I've attached the diagram along with my impression of the piston and the probable location of the two small seals. Don't ask me where the large one in the kit belongs.

I'm afraid I can offer no practical experience of actually fitting seals but thought that this may offer some light on the subject.

As I'm unable to put this information on the bulletin board, I would be most grateful if you could add some kind of thread on my behalf. Many thanks and good luck.

Regards

Jack
Saul

Jacks diagram (which I can forward on request) hints that he believes two of the seals sit at the ends of the piston chamber.

Neil seems to suggest that the seals actually sit close to the valves with the control rods running through them (ie. the main release value and the two front/rear selection valves) and looking at the shape and size of the seals (with holes running though their centers) I would have to agree that this does seem likely.

However it still doesn't help me get to the old seals. Or indeed identify them as such when I do (due to them being "rock-hard and hard to identify as seals") - I don't want to start prising things out of the pump that might be seals, in case they aren't and I end up damaging surfaces of vital components.

What am I best to use to clean things up inside the casting. Meths?
I believe you are correct Neil that the majority of the problem would probably be sorted by a good clean-up. The inside of my pump is full of a quite stunning thick brown goo. Yum.

However having purchased the seals from the register I am keen to fit them while I've got the thing on the work-bench (kitchen table - sorry Mrs Duck). I just find it slightly strange that these items are sold by the register with (it seems) little knowledge of how (or where) they should be fitted. Somebody must have bought and used them before?!

Anyway thanks for your help thus far guys.
Any further info will be most gratefully received and in return I'll let you know if I have a break-though over the Easter weekend (whilst avoiding any kind of contamination of the pump with chocolate egg residue).

Cheers,
Saul.
Saul

Saul,

When you get to solving the conundrum maybe you can take loads of digital photos and work up a sheet for Y owners. I guess we are all fortunate in having working systems - though I cannot speak for those on my YT maybe David Pelham can :-) - but I would suspect that your gunge comes from someone having used the wrong fluid in the past - you might consider a flush of the full system too. Though how you do that I dont know, I am no hydraulic engineer!

If you get really stuck, post me your pump (insured for a large amount) and I will have an hydraulic engineer here look at it for you. Send me the pesky seals too and we'll get it sorted for you gratis except for return post!

Paul
Paul Barrow

Thanks Paul, but I had another look yesterday evening and I think I've finally got to the bottom of it now (literally)!

The three seals do sit at the bottom of the three control valves just as Neil suggested.
The two larger seals are for the Front and Rear shut-off valves and the third smaller seal is for the main release valve.
I haven't yet taken apart the front/rear valves mainly because I haven't got a tool that will allow me to unscrew the two bits on the top that have the slots in, either side of the valve pin, and partly because I'm not that bothered whether I am able to restrict the jacking to the front or rear only. (I imagine though that I will take these apart to aid with the clean-up and just so I can put the new seals in seeing as I've got them).
I have however taken apart the main release valve. Once I had unscrewed the long collar that the valve pin runs through instead of being confronted with a knackered old seal (as I had hoped) I was instead confronted with what appeared to be another metal collar that looked very much like it was fixed in place or even part of the casting. It certainly didn't shake out. Yesterday I decided that however permanent this bit of metal looked it absolutely had to be removable so I bit the bullet and attempted to prise it out with a small screwdriver (all the time muttering under my breath "I can't believe I'm doing this" with imaginings of permanent damage being caused). Pop - out came something akin to a big fat copper washer about an eighth to a quarter of an inch thick, and under that was a knackered old seal!
Hoorah!
Removing the old seal revealed the valve seat. Out of interest the old seal was black instead of green, incapable of providing a good seal, but instead of being rock-hard was in fact much softer than the new seal.

I will take some photos once I have finished taking it all apart and cleaned it all up (a lovely mucky task for the Easter weekend). I am definitely on the home straight now though.

I imagine that a complete system flush would be a good move, however I'm not keen on messing with the jacks or even the pipe connections to them if I can help it. My plan is therefore to completely clean the pump (and it's filters), the reservoir, and the pipe that connects the two. I'll then put it all back together and if it works okay I'll leave it for a year or two before taking it apart again to check the filters and see if it would benefit from another clean-up. A few more years down the line and a couple more changes of hydraulic oil later I would hope that most of any residue in the system would have been flushed.

I just hope it works when I put it all back together!

Cheers,
Saul.
Saul

Knowing absolutely nothing about it - which sometimes is an advantage as it enables totally unrestricted thinking - my guess is a soft seal will be about as much use as no seal compared to the correct seal when dealing with high pressure.

I still think you should do the photos and the "instruction" manual for the Register please. Send me the photos seperate from the words incase I need to doctor them to change the contrast or make them B&W for inclusion with the seals. We will run our results past Neil to ensure we get the Technical aspects right. A color (oops lapsing into the vernacular there) or moreaccurately colour version could be a PDF download from the site maybe too.

As to flusing the system I wouldnt recommend taking the pipes and jacks off the car, but maybe you could flush the pipes and jacks on the car? No idea what you could use, but you are ideally located in Winchester. I would suggest you take the car down to Winnall and ask Dunlop Hiflex if they can remommend how you could do this under pressure - maybe bleeding through the bleed valve on the jack cylinders (they must have one I guess). It will amuse the boys there if nothing else!

Paul
Paul Barrow

Saul

You should get a reasonable amount of flushing by draining and filling the reservoir with new fluid, cycling the jacks a few time, then draining and refilling again. A couple cycles of this should get rid of most of the old fluid and much of any dirt in the system. IF there is a vent at the cylinders bleeding there would be even better but I don't remember any from the last time I filled my system "from scratch" (20+ years ago).

HTH

Larry
49 YT
Larry Hallanger

Have pulled the pump apart about 3 times, First cleaned it up, It was a mess of dried crud everywhere but was uable to remove the last of the three seals, was afraid of damageing the unit untill today just took a screw driver to it and forced the brass unit out and out came the old seal. It was not in bad shape but replaced it with a new one. Will have to wait a few years to see it it works the car project continues.
Frank
Frank Russell

This thread was discussed between 21/03/2005 and 26/03/2005

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