Brake Issues

[harleyrkc]

I'm finally getting around to looking into my brakes. The truck was just picked up this last Tuesday so its all new to me. I've been digging into the TM's and most of it is very well laid out, but while looking under the truck to check the overall condition before I tried bleeding anything, I found a small line disconnected and kinked up. I wasn't able to locate the line in question in the brake line schematics but I did manage to trace it up to vent, so I now know what it was. While looking into that I also noticed two small tappings on the side of the master cyclinder that don't have anything threaded into them. I couldn't get my head close enough to look into them but when checking them with a mirror and light, it appears there are small holes in the bottom of the tappings.

1) Does anyone know what the two tappings are on the side of the master cylinder facing away from the truck frame?

2) Is it possible that one of them is supposed to be vented?

3) If the vent line does tie to one of them, what ties to the other?

4) Does anyone have a picture or can someone take a pic of the side of there master cylinder?

 

[AceHigh]

The cap to the MC is attached to a vent line.

 

[jeffhuey1n]

You are in luck. I just replaced a master cylinder. First picture is the one I removed and am going to rebuild as a spare. The second is installed on one of the other trucks. As you can see in the second picture, they aren't used. Neither is used as a vent hole. There is a vent that is supposed to be coming out of the top of the filler cap. i have two different tyes of vents. Two of my trucks have a 90 degree fitting which a small diameter line goes into and the third has a vented cap that screws into the top of the filler cap. I'm replacing thae last with a 90 since the lines are installed and I want to keep all three trucks the same.

You have 6 total holes on the master cylinder that are used. 4 on the face that mount to the cylinder base and 2 on the bottom that the skid plate bolts to.

Let me know if you have any more questions.

 

[harleyrkc]

The cap to the MC is attached to a vent line.

The plug fitting on mine has the same little vent fitting screwed into it that I found on the end of the vent line thats ran up under the hood. But what you just described is what I saw pictured in the TM. So if I were to replacet he kinked line, what size should it be? The line that I believe must have been connected there is currently 3/16". Its tee'd into a 1/2" copper line that also connects to the side of the diaphram assembly below the MC. Does that sound right.

Also is there some place in the TM I'm missing that shows the vent lines for the brakes? I would have thought they'd have been shown in the brake line schematic.

 

[Recovry4x4]

That is a vent line for sure. It's 3/16" and there is a PS magazine article dealing with vent line mods. The tapped holes on the side of the master cylinder are where the PTO shifter is mounted. That PTO shifter operates the winch PTO.

 

[harleyrkc]

Thanks guys, it sounds like everything is there and I think I'll replace the vent line. I like the idea of having the MC vented under the hood because I think it would be a lot less likely to get water in it.