How to add brake fluid?

[jim lee]

So this is my first 3/4 ton WC. I need to bleed the brakes but.. How in the world do you get brake fluid into the master cylinder? The silly thing is hidden under the steering box. And on top of that, its mounted at an angle. Is there some trick for doing this that I'm missing?

Thanks millions!

-jim lee

[zepher11]

One needs to remove the driver's side floor board to access the master cylinder. It's not the most convenient process. Some rig a remote reservoir and adapt the M/C cap to make it an easier process. A member here was selling the conversion for the remote reservoir:

viewtopic.php?f=9&t=13028&p=78415&hilit ... oir#p78415

Others make their own:

viewtopic.php?f=9&t=13028&p=78415&hilit ... oir#p78415

Also, The 3/4 ton Dodge WC's used a sloped master cylinder that would be level when installed. They are regularly replaced with the later level style that were used on the M37's and would be uneven when installed on a Dodge WC 3/4 ton truck. Here is what the original sloped master cylinders looked like. Midwest Military sells a reproduction of this unit:



Hopefully, this helps a bit.

[jim lee]

Yeah, thanks, helps a lot! Mine doesn't have the handy slope to it. I guess I'll start working on pulling the floor up. Sigh..

-jim lee

[G. Miskovsky]

Jim,

I made my own with a PVC glue can. Works great.

[Kaegi]

a small brake fluid bottle can fit down there to pour it in or use a funnel.
my company also sells a remote reservoir fill kit. see the classifieds. (sorry for shameless plug ;/))

[wc63-1944]

A funnel and flexible pipe is what I use. Just don't be too heavy handed when pouring the fluid in.

Cheers,
Chris.

[GoranWC51]

Kaegi: For those here that are not familiar with who you are, and the name of your company, please post the link to your website, I'm sure no one objects?


Goran N

[jim lee]

Ok, now is there some sort of adapter to hook a vacuum bleeder to the big 'Ol bleeder valve stems on the wheels?

Sheesh, I can't seem to get anywhere on this with a standard set of tools.

-jim lee

[Kaegi]

did you bench bleed the master cylinder before install? if not you need to bleed it out at the line coming out of the master, then move to the wheels. I have never needed to use a vacuum or pressure bleeder on one of these trucks. But if you do, pressure is way better than vacuum. Our kit with hose and fitting can be hooked up to a pressure bleeder if desired.

[jim lee]

Installed? No, I was just trying to bleed the brakes with the master cylinder that was already in there.

Fist hurtle was figuring out how the bleeders worked. The bolt on the end really threw me.
Then I got a vacuum bleeder thing. But there was no good way to attach it.
Next day went back to parts store with bleeder valve in hand. Standard 7/16 modern valve seems to be the ticket.
Can't pull enough vacuum to do anything with silly hand pump thing, hands are now sore.
Went back to the shop and grabbed the vacuum pump. Just about collapsed the fluid catch cup. Still no luck.
Seems something is blocking the line between the rear of the truck & the master cylinder.
Spent today pulling the master cylinder. Tomorrow will hopefully be location and repair of the blockage. (We'll see..)

Most of the issue today was pulling the Dust shield. Backing nuts in places you can't get to. Were the backing nuts originally welded to he frame?

-jim lee

[Kaegi]

if getting flow at front but not rear then most likely the hose from farm to axle in the rear is bad.

[jim lee]

Actually, never saw any at the front either.

But today, I plan on laying underneath the beast and tear things apart 'till I find the issue.

And you Kaegl, you really have no obvious links for your stuff. The of the most important things about business it to always make it easy for people to give you money.

-jim lee

[Kaegi]

I try to follow the forum etiquette and only advertise in classifieds. its under the header Remote Brake fluid Reservoirs.

[Kaegi]

your master cylinder could be no good. if you have been pumping and pumping and getting no pressure seals maybe fried. These trucks normally bleed out very easily.
open bleeder, push pedal down, close bleeder let pedal up. repeat till you get a stream. When I am alone and have no pressure bleeder, I start at the front left because I can reach the bleeder and the pedal from the ground at the same time. That is enough to get air out of the first few feet of the system at least to the junction block and front left wheel. Then I get help to do the other 3.

some times when an MC is marginal and other work is done requiring bleeding the system, the piston gets pushed down into the dirt in the front of the MC and the seal give up the ghost.

[jim lee]

I'm pretty sure the MC, as you called it is bad. There's fluid running out of the boot where the brake petal rod goes in. Its also the wrong one. Not slanted. It was a bugger to get out. But I was able to clear the lines from the rear wheels. Then moving to the front? Everything is clogged. On the driver's wheel the hose was clogged from the wheel to the axel. The tube from the driver's wheel to the T is clear, but it looks copper. I thought that was a no-no for brake lines. I'm pretty sure the hose from the passenger wheel to axel is clogged as well, but I haven't been able to get it disconnected. And I'm betting axel to frame hose is clogged like you suggested.

I think this poor thing has sat for a few decades. Luckily I think it was stored in a barn or something. I'm pretty impressed at what stuff undernieth is actually still there. I've seen so many where there's very little left to work with.

I got the 1960 pink slip for the machine. Well, when we were kids we called 'em pink slips. It showed the engine # as the VIN #. And the engine # is for an M37. So I guess sometime in the 50s they swapped out for a new engine in there.

-jim lee