.. having the hardest time bleeding the brakes.

[homelessduck]

It is definitely not leaking from the calipers or wheel cylinders.

I have been covered in oils,mud,etc. ever since I started the diesel swap. It sure would be nice to not have to get covered in that stuff every day.. Hopefully this will fix it and I can stop working on it for awhile.

 

[Danoflapper]

Don't push your luck

After I fix something, I usually can get away for a few weeks before something else happens.

 

[dave186]

so what exactly did you swap under this thing? did you go from drums to disc? Need some more info on that. You need to start at the top and work down, buy or build a master cylinder plug kit and plug the ports on the MC your pedal should be high and hard. now hook up the front or rear circuit and start working your way down. you can use line clamps to pinch the rubber hoses.

 

[homelessduck]

I swapped the 7.3l, t19, and rear axle under my '75 F100. Front is a disc brake d44 w/ chevy 8lug outers. I just got back from town. Now I see why they do not include the kit with a new MC. They decided to charge $10 for it..;p

 

[dave186]

so you have a newer ford 3/4 rear axle with drums and a chevy 3/4 front with discs hooked up to the original f100 master cylinder?

 

[homelessduck]

It is actually a MC off an f350. The axles that were under it prior to me parting it out had pretty much the same size brakes. There is no reason why the MC shouldn't be able to handle them. I just bleed the MC, and there was a good amount of air in it. After bleeding that, and the brakes again, it is still the same. I have oil shooting out of all bleeder valves, no fluid leaking anywhere...

I swear the truck is just begging to be hauled to the scapper.

 

[homelessduck]

I still haven't been able to get them to build pressure.. There is pure fluid coming from all bleeder valves, and I bleed the MC.

Does anyone have ANY other suggestions? I am out of ideas...

 

[dave186]

did you plug the ports on the MC with it installed or try pinching off the rubber lines? If you just have air in the system you should be able to "pump up" the pedal some, but it sounds like you have other issues. Just for reference do you know what diameter the MC you have installed is?

 

[homelessduck]

I am not sure what diameter the MC is. I originally installed the MC and forgot to bleed it. So I ran back to town and bought a MC bleeder kit. I removed the brake lines from the MC, with it still installed, and bleed it. There was a good amount of air, and it did firm up the pedal a LITTLE. I then reinstalled the brake lines and bleed them. I can pump the brakes all day and they still won't build pressure. I did not plug the MC ports or pinch the rubber lines.. If I sit in the truck and pump the brakes over and over the fluid level does not change, nor do I see any fluid leaking out. Harbor Freight has a cheapo brake bleeder.. I guess I can try that.. but I am about done putting $$ into this thing.

 

[dave186]

first thing I would do is plug the ports on the MC with it installed and see how your pedal feels. bleeding brakes doesnt require special tools just two people. have the person in the cab press the pedal while you open the bleeder. as soon as the fluid flow slows down close the bleeder and have your helper let the pedal up. Ive literally done hundreds of vehicles that way and dont forget to start at the wheel farthest from the MC, should be your right rear.

 

[homelessduck]

Yea, that is the way I have always done it. I just figured with the bleeder tool I could be 1000000% positive there is not air in there. I will try plugging the MC ports tomorrow. I will pick up some bolts or something to screw into the holes to plug it. Then, can I leave the secondary port plugged, installed the primary brake line, and test for pressure? That way it would isolate the front/rear.

 

[comotionman]

do not thread bolts into your master cyl ports. inside the ports are brass flared seats that are pressed in and you will ruin them with bolts. you need inverted flare plugs if you want to do that.

 

[dave186]

the plastic plugs that usually come with the MC will do good enough to tell us what we need to know.

once that checks out you need some of these to pinch the rubber lines. be careful if your lines are old its possible to damage the inner lining.

You must be registered for see images attach

 

[Knuckledragger]

You are moving closer to the solution. Brake bleeding is not an art, but it does require some patience. On the sheet of paper (in the box with your new MC) that everyone throws away, there are some important instructions that will help. First, pour brake fluid very slowly. Second, do NOT pump and pump the pedal to bleed it. Push slowly down and hold it. Open bleeder, close bleeder, repeat until there is no evidence of air. Move to next wheel and repeat process. You have bled the MC properly, I hope. The main deal is not to reintroduce air into the system. If you pour the fluid too fast or down the middle, pump the pedal, or lift the pedal while the bleed screw is open, you run the risk of bringing air into the system. Check the hoses for cracks, too.

It is possible for the calipers to have an internal leak, but the piston boot will swell to indicate something is wrong and eventually fail.

If you have a vacuum power brake booster, the MC can leak into that (but you have a new MC, so that should not be an issue).

Best of luck!

 

[homelessduck]

do not thread bolts into your master cyl ports. inside the ports are brass flared seats that are pressed in and you will ruin them with bolts. you need inverted flare plugs if you want to do that.

I had those in mind. I don't know why I said bolts.

the plastic plugs that usually come with the MC will do good enough to tell us what we need to know.

once that checks out you need some of these to pinch the rubber lines. be careful if your lines are old its possible to damage the inner lining.

You must be registered for see images attach

I'll pick one of those up.

You are moving closer to the solution. Brake bleeding is not an art, but it does require some patience. On the sheet of paper (in the box with your new MC) that everyone throws away, there are some important instructions that will help. First, pour brake fluid very slowly. Second, do NOT pump and pump the pedal to bleed it. Push slowly down and hold it. Open bleeder, close bleeder, repeat until there is no evidence of air. Move to next wheel and repeat process. You have bled the MC properly, I hope. The main deal is not to reintroduce air into the system. If you pour the fluid too fast or down the middle, pump the pedal, or lift the pedal while the bleed screw is open, you run the risk of bringing air into the system. Check the hoses for cracks, too.

It is possible for the calipers to have an internal leak, but the piston boot will swell to indicate something is wrong and eventually fail.

If you have a vacuum power brake booster, the MC can leak into that (but you have a new MC, so that should not be an issue).

Best of luck!

I guess it could all just be bad luck, and I keep letting air in some how. I have NEVER had this much trouble bleeding brakes before. The piston boot does not swell, lines aren't cracked, there is no fluid leaking out, and I always kept the reservoir topped off.

Everything on this truck has given me hell, so it might just be bad luck as I said. I will give it a few more tries before I give up on it.


Thanks for the info and help guys.