Brake master cylinder leaking fluid into servo

[Pabloako]

Hi everyone,

I have a slightly strange one, where I am getting through quite a lot of brake fluid and the reservoir could need 200mm after a couple of hundred KM.

Front calipers and rear drum cylinders are brand new and zero leak is visible.  All brake pipes and connectors are nice and dry and the pressure regulator is all nice and dry too.  The brakes work well and the peddle is nice and firm too and I do not have any signs of fluid leak on the floor.

Any ideas where this fluid could be going?  Is there a chance it is getting into the Brake Servo and up the vacuum pipe?  The engine idles fine and seems to be running nice and happy.

[Pabloako]

Hi everyone,

I have a slightly strange one, where I am getting through quite a lot of brake fluid and the reservoir could need 200mm after a couple of hundred KM.

Front calipers and rear drum cylinders are brand new and zero leak is visible.  All brake pipes and connectors are nice and dry and the pressure regulator is all nice and dry too.  The brakes work well and the peddle is nice and firm too and I do not have any signs of fluid leak on the floor.

Any ideas where this fluid could be going?  Is there a chance it is getting into the Brake Servo and up the vacuum pipe?  The engine idles fine and seems to be running nice and happy.

I answered my own question.  I removed the flexible vacuum hose from the solid pipe near the engine and brake fluid trickled out.  I guess I need to buy some parts now. 
I will work out how to clean out the servo, because they aren't cheap.

This also probably answers why after a long drive down hill, I can get a puff of white smoke out the back when I accelerate again. I did think oil was getting into the cylinders, but was confused why it was white smoke and not blue.

[grumble]

I answered my own question.  I removed the flexible vacuum hose from the solid pipe near the engine and brake fluid trickled out.  I guess I need to buy some parts now. 
I will work out how to clean out the servo, because they aren't cheap.

This also probably answers why after a long drive down hill, I can get a puff of white smoke out the back when I accelerate again.  I did think oil was getting into the cylinders, but was confused why it was white smoke and not blue.

It will be sucked past the master cylinder secondary seal by the vacuum, the easiest repair is replace the master cylinder as they are usually pitted in the bore.

[Pabloako]

It will be sucked past the master cylinder secondary seal by the vacuum, the easiest repair is replace the master cylinder as they are usually pitted in the bore.

Perfect, thank you.  Do you think there will be fluid in the servo, which I somehow need to be clean out?
Also, would the diaphragm inside the servo be ok with being in contact with brake fluid?

[grumble]

Perfect, thank you.  Do you think there will be fluid in the servo, which I somehow need to be clean out?
Also, would the diaphragm inside the servo be ok with being in contact with brake fluid?

The following is how I did these in my workshop -no responsibility will be accepted if you decide to follow them as there are many factors out of my control.
I would say there is a good possibility that there is fluid in the booster, there are several ways to try to get it out. I would try removing the vacuum pipe and grommet and feeding a piece a piece of wire with a rag secured to the end into the booster very carefully and try to soak the fluid up, depending how much fluid is in there or you may have to remove the booster to empty it. Because there is fluid in the tube the last option may be necessary.

[Pabloako]

Thanks for the tip. I took the master cylinder off and found that the servo was completely full (up to the large centre  hole that the cylinder goes in to) of brake fluid.  
I used the lawn mower oil extraction pump to suck most of it out and then got an old rag in there to clean out the rest.

Now I just need the new master cylinder to turn up.

This is strangely being too easy so far.

[grumble]

Thanks for the tip. I took the master cylinder off and found that the servo was completely full (up to the large centre  hole that the cylinder goes in to) of brake fluid.  
I used the lawn mower oil extraction pump to suck most of it out and then got an old rag in there to clean out the rest.

Now I just need the new master cylinder to turn up.

This is strangely being too easy so far.

Good work bleeding the system is not so hard. While the reservoir is empty take the opportunity to clean it out, after fitting the master cylinder I open the longest line and let the fluid gravity drain through until you get clear fluid, then move to the other side and repeat for the other wheels. If you need to you can work the brake pedal from underneath the floor and watch the fluid for air bubbles.

[Mordred]

You may need to replace the booster as well as brake fluid kills the rubber bellows inside the booster. Not a cheap replacement.  I have heard the replacement boosters available need a bracket mod on the body (the front suspension tube) as it doesnt have the same holes layout.  There was a mob in Adelaide that does renewal of the booster bellows so might be worth looking at that as an option.

Adrian

[Wayne Murray]

You still could get a booster that you didn’t need to modify any thing , just need to shop around and make sure you get one with the correct hole pitch.

[Pabloako]

You still could get a booster that you didn’t need to modify any thing , just need to shop around and make sure you get one with the correct hole pitch.

Thanks everyone. I ordered a new booster and Master Cylinder from California Import Parts (https://www2.cip1.com) and they had one that doesn't need modifying.  Even with the horrible exchange rate, they are much cheaper than I could find here. (Also in stock too).  I prefer to buy Aussie stock, but the price difference stopped that this time.

The parts were shipped on Monday and should arrive tomorrow and in time for the weekend.