Problems with bleeding brakes

[GreatWhiteNorth]

Yet another problem on the '67 Series IIa NADA 109. I have finally gotten the new brake line and wheel cylinder on, and I'm ready to start bleeding the brakes. I'm afraid the master cylinder got way too low during this process...almost dry in fact. I'm totally unable to begin bleeding the brakes now...the brake pedals just travels up and down freely, and it's not moving any fluid or air into the lines. I tried hooking up the brake bleeding vacuum pump and bleeding from the wheel cylinder, but can't get any fluid into the lines. I've tried on all four corners and can't get a drop out. The resevoir is full.

Sounds like the master cylinder has air in it now, but I have no idea how to bleed it. Plus it looks like a real PITA to get to the lines coming out of the resevoir. Any suggestions?

[jac04]

Sounds to me like the piston in the master cylinder is stuck. It fits all the symptoms - pedal moves freely since it is only working against the return spring, and you can't get any fluid into the lines beacuse you're not moving the piston. Also, the stuck piston is isolating the reservoir from the lines - that's why the vacuum pump won't work.
Not sure how to get it back - maybe try pressurizing the system at one of the wheel cylinders.

[GreatWhiteNorth]

Not sure how to go about doing that...I do have an air compressor, but I'd have to rig something up to use it on the wheel cylinder bleed screw. Can you pressurize from the resevoir? I read something about using an old bicycle tube to pressurize the resevoir, but I don't exactly have one of those laying around.

[Nium]

MacGyver

I feel the spirit of MacGyver takin me over.

Cut the bicycle inner tube either side of the valve by a few inches. Seal up one end some how. Tie it off with string or maybe cut one side long and tie a knot in it. Slide the other end over the open reservoir and secure it there with string, zip ties, or a radiator clamp. Ooooh yeah a radiator clamp. Using a very low air pressure inflate the tube just a wee bit with the air compressor by facilitating the valve on the inner tube. Voila pressurized master cylinder. I've never tried it but I'd bet it'd work and would probably be less messy, in case it blows off, with a minimum amount of fluid in the reservoir. When your done use the valve to deflate.

Or don't even use the air compressor. Cut the tube in half. Secure one end to the reservoir with the radiator clamp and roll the other end, like you would a tube of toothpaste to get the last bit of toothpaste out, toward the the reservoir. That should pressurize the reservoir with a low pressure and less likely hood of over inflating due to too much pressure.

For my next MacGyvering I'll need two paper clips, a bit of gum and a duck...

Best o Luck

[GreatWhiteNorth]

Got it without a bit of McGyvering. Not sure how I got it, actually...I'll chalk one up for the grace of God. Was able to get my brakes bled, but...

Can't get them solid enough, yet. Still takes 3 or 4 pumps until they get hard at all. Looks like I'll be doing some research on how to adjust them...any tips welcome.

[jac04]

Pressurizing the master cylinder reservoir will do nothing for a stuck MC piston.

The piston probably slowly 'un-stuck' itself since there is a spring behind the piston. When bleeding, try not to depress the brake pedal beyond its normal operating range.

Adjusting the brakes is quite simple. Jack up a wheel, spin the wheel by hand while turning the adjuster until you hear just a bit of shoe drag on the drum. Do this for all 4 wheels, then try the brakes. If the pedal is firm, then the shoes were out of adjustment & re-adjust all 4 brakes again after a spin around the neighborhood. If it doesn't help, then you have more bleeding to do.

[kevkon]

I'm sure you don't want to hear this, but given that you have had a bad wheel cylinder and now a "stuck" master I would seriously consider draining the whole system and replacing or rebuilding the master. That master is a pretty simple device. Basically it's a plunger with a piston seal in a housing with a spring. If it got stuck chances are that's an indication of water corrosion or debris fouling it. I don't know that I would chance letting it go.

[Bertha]

109's are very tough to bleed. I feel your pain, I have been there. First step is to bench bleed the m/c well, before putting it in the truck. Next step is to work from the rear wheels cyl's forward. Best is to have a 2nd person helping you, as my vacum pump bleed system cant seem to make it happen on my 109. The biggest problem I have found with the brakes, especially 109's, is that the new shoes comig through dont arch exactly perfect to the drums, creating uneven contact spots. This is why you need to pump it the 4x to get the hard pedal. After the shoes get seated in somewhat(new ones never seat in perfectly) you can probably get a firm pedal after 1- 2 pumps. Good luck.

[bobzinak]

bleeding 109 brakes

You MUST minimize the air in the wheel cyl. esspecially the upside down one, on the top I think.. in my older white bible (not the green one) I specifically states that you must slacken off the brake shoe adjustment to minimize the volume of the wheel cyl. if not you will not be able to expell all of the air in the wheel cyl. I had a friend put probably a gallon of castrol trying to get the air out. including putting the vehicle on a very steep slope. more than one 109 owner seems to think that having to pump the brakes a few times to stop is somehow normal. so back off the brake adjustment on the wheel your bleeing for both shoes, and bleed as normal. this should fix your problem..bobzinak..

[GreatWhiteNorth]

Alright, I'm heading out now to give this another try. I'm going to slacken off the adjusting nuts and re-bleed, and then adjust the brake shoes to spec and see how that works. Wish me luck...

[jac04]

There is also a trick that 109 owners (and post-1980 88" owners like me) use to get the front brakes bled. It involves removing the brake backing plate, complete with the brakes in place, but keep the brake flex line attached. You then set the assembly on a block with the drum down and bleed screw facing up. This puts the inlet & outlet of each cylinder at the top. Then bleed the brakes and put everything back together. Easy, huh?

I can't tell you whether or not it works yet because I haven't gotten around to putting my brake system back together. However, I plan to use this method at re-assembly along with a Motive pressure bleeder. I hope it works.

Check it out: http://www.nickslandrover.co.uk/archives/466

[GreatWhiteNorth]

Well, I got it down to one pump and that's going to have to do for now. The next owner can have a more extensive look at it if he/she likes, as this vehicle is now for sale!

[Bertha]

Well, I got it down to one pump and that's going to have to do for now. The next owner can have a more extensive look at it if he/she likes, as this vehicle is now for sale!

I have yet to see one get better than that.

[jac04]

My Lightweight has the 109" front brakes. When I bought it, the brake pedal was dead solid and the vehicle stopped very well. So it should certainly be possible to get a good brake pedal with the 109" brakes.

Now, since I was into the rebuild pretty deep and didn't know the history of the existing components, I decided to replace the entire brake system (MC, lines, wheel cylinders, shoes, springs, and drums).
However, I found exactly what Bertha is talking about with the new front Britpart shoes from RN. Actually, had I know they were Britpart I wouldn't have bought them. Anyhow, the new bonded type shoes didn't fit the drums well, and they actually hung up on the posts that contact the adjusters. The posts were too long and hit the backplates, so watch out for that too. My original riveted type shoes had lots of meat left, so I decided to use those.
When I finally get around to bleeding the system, I'll report back on my success.

[jac04]

When I finally get around to bleeding the system, I'll report back on my success.

Well, I just finished bleeding my brakes using the method in my above posts. It seemed to work well. The pedal very firm with no signs of air entrapment. The vehicle doesn't run yet, so I'll have to see how they feel once the engine is running and the booster is operating, but it really shouldn't affect the firmness of the pedal.