Whats with my Brakes??

[Aussie Bloke]

G'day everyone,....



For those who haven't read the 'Australia' thread I think I may have a slow leak with my brakes.

So let me start from the beginning,....

When I collected my Deuce I got 30mtrs out the gate to find I had NO brakes,....
It just so happens some moron wrapped chain around the front axel and crushed the brake line either in transit from the US or more likely when it was moved from the docks here to where it was moved to be cleaned because AQIS failed its inspection, some other idiot in Yokohama must have taken it for a joy ride while it was there for a month until it was put on another ship to Australia.

But I digress,...


Anyway I had it fixed and it was filled with Dot 5 fluid.

When I got it to where I am storing it the fluid level was still full.

The next time I went to drive it (1 week later) the fluid level was below the low mark on the remote reservoir so I filled it.

The next time I needed to drive it (again 1 week later) it was only at the half way point between full and low, so I filled it again.


At this point I was telling myself it must just be air in the line working its way out up the line,...

At this point I have used almost 400ml of fluid.

So I collected it again this morning (yet another week) and again it was just a hair above the low mark.

I don't have any signs of a leak anywhere, so where is it going??

Its got me stumped.

Is the remote reservoir supposed to be connected to the master with only a spring clip??

Could it not be holding tight enough?


The brakes work great and the level dose'nt get lower overnight, It only has dropped when it has sat for a week.
That's what I find strange.



Aussie.

 

[loosescrews]

I've had this happen on other trucks, and here's how I had to proceed:

1. Fluid is missing and must be going somewhere.
2. check ground and frame for leaks
3. check airpack drain for fluid (little hex on rear lower side)
4. check brake drums thru inspection access
5. remove all drums and inspect.

Doing things in this order, I have never not found the leak. Good luck and start simple. Fluid loves to hide in the airpack and drums. The spring clip is ok for some, but I would rather have a screw type clamp.

 

[frank8003]

If fluid can not be found leaking anywhere externally that can be seen then it has to be where it can't be seen. When you pull all the wheels and drums off to do your necessary inspections you will find where the fluid is going.
You only added less than a pint so far. I think each shoe can hold about a pint.
There is a good story about remote reservoirs and picture of thirsty brake shoes for you to ponder.
View attachment brake fluid reservoir nn17 10012006.pdf

Pay special attention to first part of second page of the PDF and remove that thin little shiny plate under the master cylinder cap.

 

[Floridianson]

There also was a MWO to disconnect the master cylinder vent from the fuel tank / road draft tube if it has not been done already.
I agree you should pull drums and pull back the rubber on the wheel cylinders and R&R if needed. With the age of most of the trucks I have worked on if I don't replace the wheel cylinders and I have to replace the master the extra pressure of the new master seems to always blow out a wheel cylinder. I now replace all wheel cylinders when I do a master and this also allows me to switch to Dot 3 too.

 

[Big Dumb Truck]

I have the same issue. I am positive that it's leaking out of the master cylinder cap. I want to blame the copper crush washer. With very little room to turn a 3/4" wrench, it's hard to get enough torque on the cap to crush the washer.
I haven't had time to repair it. Some day I'll get around to it.

I may try to find an oil pan plug gasket to replace the crush washer.

 

[Floridianson]

The master cylinder boot can hold a lot of fluid and not drip.
If one decides to change out to Dot 3 you need to blow out all the brake lines with air before you hook up the new wheel cylinders. This can be done with the power bleeder that will be used to bleed the brakes before you load the bleeder with Dot 3 or shop air.

 

[frank8003]

I am positive that it's leaking out of the master cylinder cap. I want to blame the copper crush washer.

Fluid goes out, dirt and air go in..................

Problem on my MC is part 8 on the attached. Took me long time to find the correct crush washers.
View attachment master cylinder part 8.pdf

 

[frank8003]

With very little room to turn a 3/4" wrench, it's hard to get enough torque on the cap to crush the washer..........

take off the other stuff and use a socket wrench on it.

 

[frank8003]

OK
Owner is not working on it
Somebody else is working on it
I submit some pictures for the General

 

[Big Dumb Truck]

take off the other stuff and use a socket wrench on it.

I don't have a 4 sided socket in that size. And I'm not sure I would be able to get one.

 

[frank8003]

I don't have a 4 sided socket in that size. And I'm not sure I would be able to get one.

It is to dark to go look now and play with tools
but is the square size 3/4" on the master cylinder top plug?
One can bend up a 3/4" open end to use or an 8 point 3/4" socket
or a 19mm 8 point socket or a 3/4" crows foot or use a 3/4" extension rod (backwards) and drive it with a wrench on the male end. May have to grind some to get the female end flatter. These are all under 10 bucks delivered on the popular auction sites and at Harbor Fright.
Last time I replaced the master cylinder (due to previous owner capping off the vent) I cut out the offending metal buttress that was in the way of my progress.
And when you go look for a socket search for a double square socket instead of an 8 point socket.
Pictures pictures for the General.

If it wasn't so early/late I would go see if inner drive piece on the geared lug wrench would fit it.