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MG Midget and Sprite Technical - changing clutch fluid

I've decided it's about time I changed the clutch fluid as its looking a bit dark brown. I've declined from doing it before because of the horror stories I've heard about how the air can never be got out effectively. What is the recommended way to ensure a trouble (and bubble) free operation. 1971 Sprite, 1275 standard gearbox.
Steve Church

remove the cylinder from the gearbox, push the rod right back and hold back with a cable tie, I use an easybleed, and push the old fluid out with the new, allow a good litre to act as a flush and all should be good
Alex Sturgeon

Steve,

Alex is correct, BUT...I dont know that id trust an easybleed, get under the car, have someone press the pedal slowly while you crack open the valve when they reach the bottom, close the valve and have them add more fluid, and repeat the process tell you get good clean fuid.

At the risk of another huge fight on the BBS, id recommend castrol LMA brake fluid (or another plant based brake fluid) instead of the common everyday Petroleum based dot 3-4 brake fluids. Unless you have recently rebuilt the masters and slaves with modern day petroleum based rubber seals...if there the old seals, the rubber most likely be plant based.

If you cross the 2 and have the old plant based seals, you will know it in about 6 weeks when you get alot of black gooy gunk in the masters and thur the lines....thats your seals desolving and turning into bubble gum.


As they say in the WWF..."LETS GET READY TO RUUUUMMMMMBBBBBLLLLEEEEEE!!!"
let the blood bath begin...LOL

Prop...I hate brake fluid threads...Prop
Prop***The End in 2012

BTW...Im not up to the fight, So I am taking this round off, you can find my arguements and responses in the Arcives....LOL.

Maybe next time...LOL

Prop
Prop***The End in 2012

I hate easybleed. Never got it to work properly no matter what I did.

So I just do the old method where you need a beautiful assistant. It works.
Rich Amos (1 Sprite 1 Midget!)

Prop, thanks for that. The rubbers may have been changed in the early 90's by the PO. I don't think I've come across anything other than DOT4 fluid.

There seems to be some debate as to the use of DOT3/4 with rubber seals. I note a previous thread on here where one contributor stated that DOT3/4 does not contain any petroleum product.

Is Castrol LMA available in the UK?
Steve Church

Im a fraid i dont know about LMA and the UK steve, Same here on the easybleed, but they do work in a jam, if you can get a tight enough seal on the plastic hose

I like to have never learned this as I kept rebuilding my brake system over and over with kits and replacement items....you can use plant based fluid with petroleum based rubber, just not the other way around...

My guess if it was rebuilt in the 90's you maybe okay, I know Only "Ray bestous" kits here in the USA are made from petrolum based rubber for the pre-75 rubber kits,

Still if you can avoid the hassle of learning all this by finding a plant based brake fluid your well ahead of the game....try an old hole in the wall brit repair shop with an old guy thats seen it all, most likely he can tell you the names of the old stuff that works.

prop
Prop***The End in 2012

No fight but how about a stupid question for comic relief? By easybleed you mean those check valve units and not Mighty vac with the little pump?Sorry---Hank
Hank Wilson

Hank

easibleed is a simple device that fits onto the cap of your master cylinder. It has a bottle attached that holds about half a litre of brakefluid. The other end of the bottle has an adapter that fits on a spare tyre valve

to use

tightly fit the cap to the brake cylinder. Now tighten it up again! Make sure the seal is in good condition. Fill the attached bottle with brakefluid and ensure the cap is tight, very tight.

Then attach the air valve to a spare tyre (usually with no more than 10 psi inside)

the setup will push fluid into the brake or clutch master cylinder, BUT because the technician (YOU) has tightened everything there will be NO air leaks or fluid leaks! nothing else will happen

THEN go to the device to be bled, clutch or brake slave cylinder and release the nipple slowly (it is advisable to put a hose pipe on the nipple)

Then watch the air bubbles being pushed steadily out of the nipple

when the air disappears, close the nipple, extract the airvalve off the tyre and check the pedal.

it may be necessary to refill the reservoir bottle and do it again, but I doubt it, if you do it right.

never use a high tyre pressure though or you may get fluid everywhere

I have used mine for nigh on thirty years...
Bill sdgpm

I also like the Easibleed device.
The only thing that always irks me is that they didn't design it so that the reservoir bottle cap had the same thread as is normal on the 1 litre bottles of brake fluid. Then you could use it direct off the bottle, instead of decanting into the reservoir bottle with the inherent risk of introducing air bubbles.

Small detail, but so simple to achieve.
Guy Weller

<< BUT because the technician (YOU) has tightened everything there will be NO air leaks or fluid leaks! >>

But until you've suceeded in doing it correctly and worked out what rubbers and seals you actually need, you will experience the several itterations of the following:

1) Put fluid in the bottle
2) Connect the bottle to the master cylinder
3) Connect the spare tyre
4) Watch in amazement as the bottle slowly empties and brake fluid sprays out of the master cylinder all over your engine bay.
5) Disconnect the tyre
6) Disconnect the M/C (creating more mess as the pipes and M/C are full, and I mean FULL, of fluid)
6) Mop up the mess
7) Put a different set of rubbers / seals into the M/C cap
8) Go to the motor factors and buy another litre of brakefluid
9) Start again

This continues until
1) Saturday evening arrives and the motor factor closes, thereby removing your endless supply of brake fluid.
2) You magically find the correct number of rubber seals to use.
3) You admit defeat, throw everything away except the variety of plastic pipes from the ezibleed kit, retaining those to bleed the system by the good old open, push, close, release method.

A syringe is an indespincible tool in my tool box. Wonderful for removing as much old fluid as possible from the M/C, before filling up and using the old fashioned two-"man" bleeding method. Alternatively you can use the syringe to suck the fluid through from the bleed valve end - now why didn't they invent an ezi-bleed kit that sucks instead of blows? the plastic pipes from the ezi-bleed kit are great for use on the end of the syringe and the end of the bleed nipples.

As an aside, I've also seen a brand new vacuum pump destroyed by use as a newly invented brake bleeding suction pump. The fluid disolved the seals in the pump and guage. And no, it's wasn't me, but it was my vacuum pump!

Ant
Ant Allen

I have used an eezibleed many times for the clutch and it never fails, but DON'T use it in the recommended fashion. Open the clutch slave bleed valve and pump all the old fluid out. You need an empty system.

Let your chosen tyre down to less than 10 psi and take off the master cylinder cap. 3/4 fill the eezibleed with new fluid and attach with suitable pipe to the slave cylinder bleed valve. Plug on to the tyre valve, then open the slave cylinder bleed valve.

The fluid will slowly rise up the pipe pushing all the air before it. You must have low, low pressure. 5 psi is good. Look inside the master cylinder. When it is about 1/2 full, nip back under and close the bleed valve. Disconnect everything and voila, perfectly working clutch. I've done this many times and it has always worked first time.
Mike Howlett

Mike,
I like the idea of introducing the fluid from underneath. Keeps it out of the engine bay. Having said that I don't have an easybleed, just one of those plastic bottles with a one way valve on the end of the pipe.
My only concern with your method is whether you can actually pump all the fluid out of the system. Obviously works for you though.
Steve Church

Only problems I have had using the Easibleed in the recommended fashion have been with too much air pressure and leaks at the MC cap. I recommend attaching it to the MC and spare tyre BEFORE putting any fluid in the bottle. Fix any leakage issues, THEN disconnect from tyre, add fluid to bottle, reconnect to tyre and bleed system. I made the mistake of loaning my Easibleed to a friend whose ham-fisted progeny bent the bejazus out of the cap that fits my clutch MC. I get to think unkind thoughts in his direction on a regular basis. I made a new one out of a plastic MC cap (and one for that huge brake MC as well). Once you realize that there ar two layers to those caps...

I do not agree with Prop about the makeup of the original seals. I do not believe they were made of natural rubber. Some of the replacement ones that you get now probably are.
David "you could always use a bicycle inner tube..." Lieb
David Lieb

David,
"you could always use a bicycle inner tube..." I presume you imply that you have done this! It used to be my preferred system until someone gave me an easibleed as a birthday present. The overfed Python bike tube method was always quite fun!
Guy Weller

I used my poor maligned Eezibleed again today...

terrible results

I had to remake a new brake pipe flare on Gwyn's Monjo and then bleed (my fault as I didn't make the flare right first time...)I put the Eb on the car as described.

BUT didnt let the tyre pressure down to the advised 10 or less psi

and when I put the adapter to the valve the higher pressure blew the joint I'd remade and fluid dripped out on my poor old clean driveway.

So I had to take the pipe off completely and remake the flare again, when refitted, again with the same high pressure there was just no leak at all.

So that terrible eezibleed saved me from a future loss of fluid when the car's bouncing and rattling around might have caused it to lose pressure again.

I'll repeat what I say every time, make sure the joints are tight FIRST then it will become a very reliable old friend. Mine handled 2.1 bar today and just did what it was supposed to.
Bill sdgpm

Guy,
You are correct! A quick romp through the archives will uncover at least twice that I have detailed this technique, although I believe that you win the prize for the "overfed python" description.
David "it can be challenging to keep from dripping" Lieb
David Lieb

This thread was discussed between 20/02/2009 and 23/02/2009

MG Midget and Sprite Technical index

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