MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Time to change brake fluid ?

Two weeks ago i ajusted my rear brakes .Igot afirm pedal and good braking.
Durig this two weeks I only used the car for short tips to go to work.Yesterday very hot day here I used it for enjoying fast driving , not too fast,after about ten miles of hard cornering and braking pedal course increased and it return to normal after half an hour of stop and returning home i had the same problem .
Is my brake fluid loosing is quality when hot or is it brakes hoses .
Thanks by advance for your advices.

Pierre
Pierre

I have this problem too no idea what it is though
erfrefewrffre werfwerfetrtg

I had this problem on my B when I first got it, after it had stood unused for many years. Combination of old fluid that as absorbed too much moisture and failing seals in the master cylinder and leaks in the rear wheel cylinders. My cure was a complete overhaul of the system: new hoses, rear wheel cylinders, new master cylinder. The front calipers and discs were done previously, so I did not have to do anything other than install new front pads. Works like new.
Andrew Blackley

Many folks have done as Andrew has and that has usually led to the same results as he has had. Old equipment and fluid is still old stuff and subject to all the shortcomings of used stuff ~ wear, tear, neglect, fouling of fluids, etc, etc.

Some folks seem to like the silicone fluids for their longevity, some, like myself are more comfortable with the more traditional forms of glycol brake fluids, but flush the system and refill with all new glycol fluids at least every two years to remove contaminants and to simply refresh possibly tired fluids. Both choices seem to have their followings, and both camps seem happy enough with their choices. The archives are full of Brake Fluid and Brake system discussions, so you may want to rummage through those in your quest for long term brake satisfaction.
Bob Muenchausen

Thanks for your advices Andrew and Bob

As I had a complete brake system rebuilt 12000 Miles ago (3 years) i mean new calipers master and slave cylinders new drums .....
I will first drain old fluid and change for new traditional fluid .
I had read that the operation of changing to silicone is a bit tricky.

Pierre
Cinquin Pierre

If you are renewing the fluid, you will need at least 2 Litres as you will need to drain out the old and flush through new fluid to remove the residual old fluid. The easiest way here is to use a one-man bleed kit, such as gunson's Eezi-Bleed. You should start at the shortest pipe length and work to the longest pipe length. Open each bleed valve and wait until you see clean, clear fluid coming through and then let some more clear fluid flush through. That way it will remove the absorbed moisture and degraded old fluid thoroughly. The same applies if switching to silicone. With normal brake fluid, beware of the paint work! And don't forget the clutch, too! It suffers the same problems.

HTH
Martin

Martin,

Not to be contentious, but more curious, I had been lead to believe in refurbishing the hydralics to start with the longest line first then work towards the shortest.

Any experiences from others?

During my resto i got new front calipers, rebuilt both master cylinders, slave and rear wheel cylinders. With all new pipes tubes fittings, etc, I went with the silicone fluid. Primarily because of its "friendliness" to paint.

For anyone thinking of making the change, I'd suggest a complete ovberhaul of the hydrolic system as the two fluids are not compatible.
glg

Pierre,
Always start with the LONGEST pipe, which is the nearside rear brake (right hand side if your car is left hand drive). If you have a brake failure switch on the master cylinder, it must be disconnected and unscrewed 31/2 to 4 turns, otherwise the system will not bleed properly. Remember to screw it up again when you have finally finished. A helper to pump the brake pedal is also handy and keeps you company. My wife has become expert at both of these jobs!
Greg Taplin

When occasion has demanded it, I have torn down wheel cylinders, cleaned and renewed internals, and flushed lines and masters, and replaced fluid, confident that no old fluid remains in the system. I am less confident that any amount of flushing through with new fluid, yearly, or at any other period , will get ALL the old fluid ( and water) out of the system, without disassembly, particularly from the individual wheel cylinders, unless the wheel pistons can be pushed back into the cylinders, to expell the contents. As always, i stand happy to be corrected, but it seems to me that wheel cylinder design precludes automatic expulsion of tired fluid by simply bleed/flushing. Am I simply incorrect? Am I being too fussy? I would love to be told so!)
Ken R.
Ken Rich

Ken
You are correct in being too fussy.
glg

Glg
from a volume point of view, there is way more fluid in the front calipers and rear brake cylinders than in the tubing. compressing the pistons will evacuate lots more fluid.

Next question do you drain the oil cooler when you change oil?

Barry
Barry Parkinson

Barry,

No. I replace both the oil cooler and filter when doing an oil change.
glg

thats surely a tad on the expesive side isn't it? A new oil cooler every 3000miles?!!!

Now that is obsessive! :->

~PHIL

Phil

I flushed my brake and clutch systems out as the history I got with the car showed no signs of it having been done in the previous 10 years. I sucked the excess out of the master cylinders with one of those syringe things that comes with a printer refill kit, before topping up with fresh. This reduces the amount of fluid that has to be bled out.Adding liquid in from the top and draining it from the bottom may not get everything out If however the fluid coming out is originally dark brown and eventually runs clear the worst contamination has been removed.

Vic
V Todman

Phil,

While doing the restoration, I just got so used to shoveling money into the "Project Car Hole" it became a normal sense of being.

Since the project was completed, just to validate my relationship and exsistence with the finished car, I have a need to spend money on it -- whether it's necessary not.

A bad habit? Sure. But not as bad as drugs. And there's even a certian amout of fun in exageration of the tale as unrelated, diverse posts of reply warrant. <;+}
glg

Greg,

Can i borrow your wife - strictly for brake bleeding purposes obviously.

Simon
Simon Crozier

My comment on shortest to longest was not so much to do with bleeding but flushing. Hope that clarifies.
However, certain vehicles do seem to be better when bled from shortest to longest.

BTW interesting comment on the failure switch. My 1980 GT has a split m/c with inline servo, and has the switch underneath. I will try that as I am struggling to get a good pedal. I also use Automec Silicone fluid and have had new m/c, calipers and rears cylinders (as well as the whole clutch).
Martin

This thread was discussed between 12/07/2003 and 15/07/2003

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.